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Editorial Office (editorial + office)
Selected AbstractsAn Invitation and Call for Papers from the Editorial Office.FUEL CELLS, Issue 5 2007Topical Issue: NOVEL CERAMIC MATERIALS FOR FUEL CELLS No abstract is available for this article. [source] From the Editorial OfficeHEADACHE, Issue 3 2003John F. Rothrock MD No abstract is available for this article. [source] Important Announcement ,Immunology's Editorial Office has moved!IMMUNOLOGY, Issue 3 2007Article first published online: 8 OCT 200 No abstract is available for this article. [source] From kitchen table to electronic editorial office: the evolution of the journalHEALTH INFORMATION & LIBRARIES JOURNAL, Issue 2008Penny Bonnett First page of article [source] IUPAC International Symposium on Ionic Polymerization Goa, India, IP2005, October 23,28, 2005MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 6 2006Durairaj Baskaran Conference Reports: This section contains reports on topical conferences. Reports are usually written at the request of the editorial office, but unsolicited contributions are also welcome. Suggestions should be sent to the editorial office of the Macromolecular journals, preferably by E-mail to macromol@wiley-vch.de. [source] Missions and Challenges of Polymer Science and TechnologyMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 8 2003Kazuyuki Horie This section contains reports on topical conferences. Reports are usually written at the request of the editorial office, but unsolicited contributions are also welcome. Suggestions should be sent to the editorial office of the Macromolecular journals, preferably by E-mail to macromol@wiley-vch.de. [source] Hermann Staudinger Prize 2002MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 2 2003Rolf Mülhaupt This section contains news of the macromolecular community all over the world. Articles about, for example, people, projects, and market trends are welcome. Suggestions should be sent to the editorial office of the Macromolecular journals, preferably by E-mail to macromol@wiley-vch.de. The editorial office decides which articles will be published. [source] Fourteenth International Summer School on Vacuum, Electron and Ion Technologies (VEIT)PLASMA PROCESSES AND POLYMERS, Issue 6 2005Nikolay Guerassimov Plasma News: This section contains news of the plasma community all over the world. Articles about, for example, people, projects, and market trends are welcome. Suggestions should be sent to the editorial office of Plasma Processes and Polymers, preferably by E-mail to plasma@wiley-vch.de. The editorial office decides which articles will be published. [source] Move of the editorial office of the American Journal of Physical AnthropologyAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2007Article first published online: 16 MAY 200 No abstract is available for this article. [source] Hexamer oligonucleotide topology and assembly under solution phase NMR and theoretical modeling scrutinyBIOPOLYMERS, Issue 12 2010Maxim P. Evstigneev Abstract The entire family of noncomplementary hexamer oligodeoxyribonucleotides d(GCXYGC) (X and Y = A, G, C, or T) were assessed for topological indicators and equilibrium thermodynamics using a priori molecular modeling and solution phase NMR spectroscopy. Feasible modeled hairpin structures formed a basis from which solution structure and equilibria for each oligonucleotide were considered. 1H and 31P variable temperature-dependent (VT) and concentration-dependent NMR data, NMR signal assignments, and diffusion parameters led to d(GCGAGC) and d(GCGGGC) being understood as exceptions within the family in terms of self-association and topological character. A mean diffusion coefficient D298 K = (2.0 ± 0.07) × 10,10 m2 s,1 was evaluated across all hexamers except for d(GCGAGC) (D298 K = 1.7 × 10,10 m2 s,1) and d(GCGGGC) (D298 K = 1.2 × 10,10 m2 s,1). Melting under VT analysis (Tm = 323 K) combined with supporting NMR evidence confirmed d(GCGAGC) as the shortest tandem sheared GA mismatched duplex. Diffusion measurements were used to conclude that d(GCGGGC) preferentially exists as the shortest stable quadruplex structure. Thermodynamic analysis of all data led to the assertion that, with the exception of XY = GA and GG, the remaining noncomplementary oligonucleotides adopt equilibria between monomer and duplex, contributed largely by monomer random-coil forms. Contrastingly, d(GCGAGC) showed preference for tandem sheared GA mismatch duplex formation with an association constant K = 3.9 × 105M,1. No direct evidence was acquired for hairpin formation in any instance although its potential existence is considered possible for d(GCGAGC) on the basis of molecular modeling studies. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 1023,1038, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Nociceptin and its natural and specifically-modified fragments: Structural studiesBIOPOLYMERS, Issue 12 2010E. Podstawka-Proniewicz Abstract The vibrational structures of Nociceptin (FQ), its short bioactive fragments, and specifically-modified [Tyr1]FQ (1-6), [His1]FQ (1-6), and [His1,4]FQ (1-6) fragments were characterized. We showed that in the solid state, all of the aforementioned peptides except FQ adopt mainly turn and disordered secondary structures with a small contribution from an antiparallel ,-sheet conformation. FQ (1-11), FQ (7-17) [His1]FQ (1-6), and [His1,4]FQ (1-6) have an ,-helical backbone arrangement that could also slightly influence their secondary structure. The adsorption behavior of these peptides on a colloidal silver surface in an aqueous solution (pH = ,8.3) was investigated by means of surface-enhanced Raman scattering (SERS). All of the peptides, excluding FQ (7-17), chemisorbed on the colloidal silver surfaces through a Phe4 residue, which for FQ, FQ (1-11), FQ (1-6), [Tyr1]FQ (1-6), and [His1]FQ (1-6) lies almost flat on this surface, while for FQ (1-13) and FQ (1-13)NH2 adopts a slightly tilted orientation with respect to the surface. The Tyr1 residue in [Tyr1]FQ (1-6) does not interact with the colloidal silver surface, suggesting that the Tyr1 and Phe4 side chains are located on the opposite sides of the peptide backbone, which can be also true for His1 and Phe4 in [His1]FQ (1-6). The lone pair of electrons on the oxygen atom of the ionized carbonyl group of FQ (1-13) and FQ (7-17) appears to be coordinated to the colloidal silver nanoparticles, whereas in the case of the remaining peptides, it only assists in the adsorption process, similar to the NH2 group. We also showed that upon adsorption, the secondary structure of these peptides is altered. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 1039,1054, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Crystal structure of an S -formylglutathione hydrolase from Pseudoalteromonas haloplanktis TAC125BIOPOLYMERS, Issue 8 2010Vincenzo Alterio Abstract S -formylglutathione hydrolases (FGHs) constitute a family of ubiquitous enzymes which play a key role in formaldehyde detoxification both in prokaryotes and eukaryotes, catalyzing the hydrolysis of S -formylglutathione to formic acid and glutathione. While a large number of functional studies have been reported on these enzymes, few structural studies have so far been carried out. In this article we report on the functional and structural characterization of PhEst, a FGH isolated from the psychrophilic bacterium Pseudoalteromonas haloplanktis. According to our functional studies, this enzyme is able to efficiently hydrolyze several thioester substrates with very small acyl moieties. By contrast, the enzyme shows no activity toward substrates with bulky acyl groups. These data are in line with structural studies which highlight for this enzyme a very narrow acyl-binding pocket in a typical ,/,-hydrolase fold. PhEst represents the first cold-adapted FGH structurally characterized to date; comparison with its mesophilic counterparts of known three-dimensional structure allowed to obtain useful insights into molecular determinants responsible for the ability of this psychrophilic enzyme to work at low temperature. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 669,677, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] ,-Sheet aggregation of kisspeptin-10 is stimulated by heparin but inhibited by amphiphilesBIOPOLYMERS, Issue 8 2010Søren B. Nielsen Abstract The murine 10-residue neurohormone kisspeptin (YNWNSFGLRY) is an important regulator of reproductive behavior and gonadotrophin secretion. It is known to form a random coil in solution, but undergoes a structural change in the presence of membranes although the nature of this change is not fully determined. The peptide's conformational versatility raises the question whether it is also able to form ordered aggregates under physiological conditions, which might be relevant as a storage mechanism. Here we show that heparin induces kisspeptin to form ,-sheet rich amyloid aggregates both at neutral (pH 7.0) and slightly acidic (pH 5.2) conditions. Addition of heparin leads to aggregation after a certain lag phase, irrespective of the time of addition of heparin, indicating that heparin is needed to facilitate the formation of fibrillation nuclei. Aggregation is completely inhibited by submicellar concentrations of zwitterionic and anionic surfactants. Unlike previous reports, our NMR data do not indicate persistent structure in the presence of zwitterionic surfactant micelles. Thus kisspeptin can aggregate under physiologically relevant conditions provided heparin is present, but the process is highly sensitive to the presence of amphiphiles, highlighting the very dynamic nature of the peptide conformation and suggesting that kisspeptin aggregation is a biologically regulatable process. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 678,689, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Polymerization and matrix physical properties as important design considerations for soluble collagen formulationsBIOPOLYMERS, Issue 8 2010S. T. Kreger Abstract Despite extensive use of type I collagen for research and medical applications, its fibril-forming or polymerization potential has yet to be fully defined and exploited. Here, we describe a type I collagen formulation that is acid solubilized from porcine skin collagen (PSC), quality controlled based upon polymerization potential, and well suited as a platform polymer for preparing three-dimensional (3D) culture systems and injectable/implantable in vivo cellular microenvironments in which both relevant biochemical and biophysical parameters can be precision-controlled. PSC is compared with three commercial collagens in terms of composition and purity as well as polymerization potential, which is described by kinetic parameters and fibril microstructure and mechanical properties of formed matrices. When subjected to identical polymerization conditions, PSC showed significantly decreased polymerization times compared to the other collagens and yielded matrices with the greatest mechanical integrity and broadest range of mechanical properties as characterized in oscillatory shear, uniaxial extension, and unconfined compression. Compositional and intrinsic viscosity analyses suggest that the enhanced polymerization potential of PSC may be attributed to its unique oligomer composition. Collectively, this work demonstrates the importance of standardizing next generation collagen formulations based upon polymerization potential and provides preliminary insight into the contribution of oligomers to collagen polymerization properties. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 690,707, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Physicochemical properties of thiol proteinase inhibitor isolated from goat pancreasBIOPOLYMERS, Issue 8 2010Medha Priyadarshini Abstract Thiol proteinase inhibitors are crucial to proper functioning of all living tissues consequent to their cathepsin regulatory and myriad important biologic properties. Equilibrium denaturation of dimeric goat pancreas thiol proteinase inhibitor (PTPI), a cystatin superfamily variant has been studied by monitoring changes in the protein's spectroscopic and functional characteristics. Denaturation of PTPI in guanidine hydrochloride and urea resulted in altered intrinsic fluorescence emission spectrum, diminished negative circular dichroism, and loss of its papain inhibitory potential. Native like spectroscopic properties and inhibitory activity are only partially restored when denaturant is diluted from guanidine hydrochloride unfolded samples demonstrating that process is partially reversible. Coincidence of transition curves and dependence of transition midpoint (3.2M) on protein concentration in guanidine hydrochloride-induced denaturation are consistent with a two-state model involving a native like dimer and denatured monomer. On the contrary, urea-induced unfolding of PTPI is a multiphasic process with indiscernible intermediates. The studies demonstrate that functional conformation and stability are governed by both ionic and hydrophobic interactions. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 708,717, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Ion channel activity of transmembrane segment 6 of Escherichia coli proton-dependent manganese transporterBIOPOLYMERS, Issue 8 2010uková Abstract Synthetic peptides corresponding to the sixth transmembrane segment (TMS6) of secondary-active transporter MntH (Proton-dependent Manganese Transporter) from Escherichia coli and its two mutations in the functionally important conserved histidine residue were used as a model for structure,function study of MntH. The secondary structure of the peptides was estimated in different environments using circular dichroism spectroscopy. These peptides interacted with and adopted helical conformations in lipid membranes. Electrophysiological experiments demonstrated that TMS6 was able to form multi-state ion channels in model biological membranes. Electrophysiological properties of these weakly cation-selective ion channels were strongly dependent on the surrounding pH. Manganese ion, as a physiological substrate of MntH, enhanced the conductivity of TMS6 channels, influenced the transition between closed and open states, and affected the peptide conformations. Moreover, functional properties of peptides carrying two different mutations of His211 were analogous to in vivo functional characteristics of Nramp/MntH proteins mutated at homologous residues. Hence, a single functionally important TMS can retain some of the functional properties of the full-length protein. These findings could contribute to understanding the structure,function relationship at the molecular level. However it remains unclear to what extent the peptide-specific channel activity represents a functional aspect of the full-length membrane carrier protein. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 718,726, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Conformations and properties of the L -tryptophyl-containing peptides in solution, depending on the pH,Theoretical study vs. experimentsBIOPOLYMERS, Issue 8 2010Bojidarka B. Ivanova Abstract The conformational preference and electronic properties of three L -tryptophyl-containing dipeptides, i.e., glycyl- L -tryptophane (H-Gly-Trp-OH), L -alanyl- L -tryptophane (H-Ala-Trp-OH), and L -methionyl- L -tryptophane (L -Met-Trp-OH) in solution depending on the pH of the media are studied both theoretically and experimentally. The effect of the protonation of the COO, and deprotonation of the NH as well as the alkaline hydrolysis of the amide fragment in a strong basic media on the electronic spectra are discussed. Ab initio and density functional theory (DFT) methods as well as the time-dependent DFT (TD-DFT) method as a function of the basis set are performed with a view to obtain the geometry and electronic properties of all of the species as well as the intermediate, obtained in the alkaline hydrolysis mechanism. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 727,734, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Terahertz time-domain spectroscopy of poly- L -lysineBIOPOLYMERS, Issue 8 2010Ohki Kambara Abstract Poly- L -lysine is known to have three different secondary structures depending on solvent conditions because of its flexible nature. In previous work (Kambara et al., Phys Chem Chem Phys 2008, 10, 5042-5044), we observed two different types of structural changes in poly- L -lysine. In the present study, we investigated the low-frequency spectrum of poly- L -lysine with a ,-sheet structure in the solid state by terahertz time-domain spectroscopy. On the basis of this spectroscopic analysis, we found that the low-frequency dynamics differed from those of other polypeptides. Furthermore, we performed powder X-ray diffraction measurement on poly- L -lysine, which was found to be highly amorphous compared with other polypeptides. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 735,739, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Stimulation of the HIV-1 integrase enzymatic activity and cDNA integration by a peptide derived from the integrase proteinBIOPOLYMERS, Issue 8 2010Aviad Levin Abstract Here we describe the features of a peptide that was selected from the human immunodeficiency virus Type 1 (HIV-1) Integrase (IN) peptide library which interacts with both, the viral Rev and IN proteins. Because of its ability to stimulate the IN enzymatic activity this peptide was designated INS (IN stimulatory). Modification of its amino acid sequence revealed that replacement of its C-terminal lysine by glutamic acid (INS K188E) converts it from a stimulatory peptide to an inhibitory one. Both peptides promoted the dissociation of a previously described complex formed between Rev and IN whose formation results in IN inactivation. INS and INS K188E penetrated HIV-1-infected cells and caused stimulation and inhibition of viral genome integration, respectively. Using cultured cells infected with a ,Rev HIV revealed that INS can directly activate the viral IN. These results suggest that the stimulatory effect of INS in wild-type virus-infected cells is due to a dual effect: it dissociates the inactive Rev-IN complex and directly activates the free IN. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 740,751, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Real-time detection of single-living pancreatic ,-cell by laser tweezers Raman spectroscopy: High glucose stimulationBIOPOLYMERS, Issue 7 2010Xi Rong Abstract Glucose acts as a ,-cell stimulus factor and leads to cellular responses that involve a large amount of biomolecule formation, relocation, and transformation. We hypothesize that information about these changes can be obtained in real-time by laser tweezers Raman spectroscopy. To test this hypothesis, repeated measurements designs in accordance with the application of Raman spectroscopy detection were used in the current experiment. Single rat ,-cells were measured by Raman spectroscopy in 2.8 mmol/l glucose culture medium as a basal condition. After stimulation with high glucose (20 mmol/l), the same cells were measured continuously. Each cell was monitored over a total time span of 25 min, in 5 min intervals. During this period of time, cells were maintained at an appropriate temperature controlled by an automatic heater, to provide near-physiological conditions. It was found that some significant spectral changes induced by glucose were taking place during the stimulation time course. The most noticeable changes were the increase of spectral intensity at the 1002, 1085, 1445, and 1655 cm,1 peaks, mainly corresponding to protein and lipid. We speculate that these changes might have to do with ,-cell protein and lipid synthesis. Using laser tweezers Raman spectroscopy in combination with glucose stimulation, optical spectral information from rat ,-cells was received and analyzed. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 587,594, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] The diversity of FtsY-lipid interactionsBIOPOLYMERS, Issue 7 2010M. E. Reinau Abstract The bacterial signal recognition particle (SRP) receptor FtsY forms a complex with the SRP Ffh to target nascent polypeptide chains to the bacterial inner membrane. How FtsY interacts with lipids and associates to the membrane is unclear. Here, we show that vesicle binding leads to partial protection against proteolytic degradation and a change in secondary structure, which differs depending on whether the lipids are simple mixtures of zwitterionic and anionic lipids, mimics of Escherichia coli lipids, or lysolipids. Lipid binding alters the stability of FtsY. Thermal unfolding of FtsY in buffer shows two transitions, one occurring at ,60°C and the other at ,90°C. The thermal intermediate accumulating between 60 and 90°C has structural features in common with the state induced by binding to E. coli lipids. E. coli lipid extract induces a single transition around 70°C, anionic lipids have no effect while cooperative unfolding is completely removed in lysolipids. Thus, the lipid environment profoundly influences the dynamic properties of FtsY, leading to three different kinds of FtsY-lipid interactions with different effects on structure, proteolytic protection, and stability, and is driven both by hydrophobic and electrostatic interactions. Trypsin digestion experiments highlight the central role of the N-domain in lipid contacts, whereas the A- and G-domains appear to play a more minor part. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 595,606, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Model peptide-based system used for the investigation of metal ions binding to histidine-containing polypeptidesBIOPOLYMERS, Issue 6 2010Manuela Murariu Abstract The reaction of histidine-containing polypeptides with toxic and essential metals and the molecular mechanism of complexation has yet to be determined, particularly with respect to the conformational changes of the interacting macromolecules. Therefore, a system of oligopeptides containing histidine residues in various positions of Ala or Gly sequences has been designed and used in heavy metal comparatively binding experiments. The role of spacing residues (Gly and Ala repeats) in selecting the various conformations was investigated. The newly synthesized peptides and metal ion adducts have been characterized by Fourier transform infrared spectroscopy (FTIR) as well as electrospray ion trap mass spectrometry (ESI,MS) and circular dichroism (CD). The analysis of CD-spectra of the four peptides in water revealed that the secondary structure depends much on the position of each amino acid in the peptide backbone. Our peptides system reveals various binding mechanisms of metal ions to peptides depending on the position of histidine residue and the corresponding conformations of Ala or Gly sequences. Biological and medical consequences of conformational changes of metal-bound peptides are further discussed. Thus, the binding of heavy metals to four peptides may serve as a model system with respect to the conformational consequences of the metal addition on the amino acid repeats situated in prion protein. © 2010 Wiley Periodicals, Inc. Biopolymers 93:497,508, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Solvation effects in calculated electrostatic association free energies for the C3d-CR2 complex and comparison with experimental dataBIOPOLYMERS, Issue 6 2010Alexander S. Cheung Abstract The complement system is an integral part of the innate immune system that participates in the clearance of pathogens from the body. The association between complement protein fragment C3d and B or T cell-receptor complement receptor (CR) 2 represents a crucial link between innate and adaptive immunities. The goal of this study is to predict association abilities of C3d and CR2 mutants by theoretically calculating electrostatic free energies of association and to assess the importance of solvation effects in the calculations. We demonstrate that calculated solvation free energy differences and Coulombic free energies of association are more sensitive than electrostatic free energies of association in solution and, thus, more accurate in predicting previously published experimental data for the association abilities (relative to the parent proteins) of specific C3d and CR2 mutants. We show that a proportional relationship exists between the predicted solvation free energy differences and the experimental data, while an inversely proportional relationship exists between the predicted Coulombic free energies of association and the experimental data. Our results yield new insights into the physicochemical properties underlying C3d-CR2 association. We discuss the predictive validity of Coulombic, solvation, and solution electrostatic free energies of association and the generalization of our method for theoretical mutagenesis studies of other systems. This is a basic study, aimed toward improving our understanding of the theoretical basis of immune system regulation at the molecular level. Such insight can serve as the groundwork for the design of regulators with tailored properties, vaccines, and other biotechnology products. © 2010 Wiley Periodicals, Inc. Biopolymers 93:509,519, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Vibrational spectroscopic studies of newly developed synthetic biopolymersBIOPOLYMERS, Issue 5 2010Rajan K. Bista Abstract Vibrational spectroscopic techniques such as near-infrared (NIR), Fourier transform infrared (FTIR), and Raman spectroscopy are valuable diagnostic tools that can be used to elucidate comprehensive structural information of numerous biological samples. In this review article, we have highlighted the advantages of nanotechnology and biophotonics in conjunction with vibrational spectroscopic techniques in order to understand the various aspects of new kind of synthetic biopolymers termed as polyethylene glycol (PEG)ylated lipids. In contrast to conventional phospholipids, these novel lipids spontaneously form liposomes or nanovesicles upon hydration, without the supply of external activation energy. The amphiphiles considered in this study differ in their hydrophobic acyl chain length and contain different units of PEG hydrophilic headgroups. We have further explored the thermotropic phase behaviors and associated changes in the conformational order/disorder of such lipids by using variable-temperature FTIR and Raman spectroscopy. Phase transition temperature profiles and correlation between various spectral indicators have been identified by either monitoring the shifts in the vibrational peak positions or plotting vibrational peak intensity ratios in the CH stretching region as a function of temperature. To supplement our observations of phase transformations, a thermodynamic approach known as differential scanning calorimetry (DSC) has been applied and revealed a good agreement with the infrared and Raman spectroscopic data. Finally, the investigation of thermal properties of lipids is extremely crucial for numerous purposes, thus the results obtained in this work may find application in a wide variety of studies including the development of PEGylated lipid based drug and substances delivery vehicles. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 403,417, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Interaction of ,-gliadin with polyanions: Design considerations for sequestrants used in supportive treatment of celiac diseaseBIOPOLYMERS, Issue 5 2010Li Liang Abstract Copolymers of sodium 4-styrene sulfonate (SS) and hydroxyethyl methacrylate (HEMA) were investigated as sequestrants of ,-gliadin, a gluten protein, for the treatment of gluten intolerance. The interactions of ,-gliadin with poly(SS) and poly(HEMA- co -SS) with 9 and 26 mol% SS content were studied at gastric (1.2) and intestinal (6.8) pH using circular dichroism and measurements of turbidity, dynamic light scattering and zeta potential. The interactions and their influence on ,-gliadin secondary and aggregated structures depended mainly on the ratio of polymer negative and protein positive charges at pH 1.2, and on polymer SS content at polymer concentrations providing in excess of negative charges at either pH. Poly(SS) could not form complex particles with ,-gliadin in a sufficient excess of negative charges. Copolymerization with HEMA enhanced the formation of complex particles. Poly(HEMA- co -SS) with intermediate SS content was found to be the most effective sequestrant for ,-gliadin. This study provides insight into design considerations for polymer sequestrants used in the supportive treatment of celiac disease. © 2009 Wiley Periodicals, Inc. Biopolymers 93:418,428, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Conformations within soluble oligomers and insoluble aggregates revealed by resonance energy transferBIOPOLYMERS, Issue 4 2010Jyothi L. Digambaranath Abstract A fluorescently labeled 20-residue polyglutamic acid (polyE) peptide 20 amino acid length polyglutamic acid (E20) was used to study structural changes which occur in E20 as it co-aggregates with other unlabeled polyE peptides. Resonance energy transfer (RET) was performed using an o -aminobenzamide donor at the N-terminus and 3-nitrotyrosine acceptor at the C-terminus of E20. PolyE aggregates were not defined as amyloid, as they were nonfibrillar and did not bind congo red. Circular dichroism measurements indicate that polyE aggregation involves a transition from ,-helical monomers to aggregated ,-sheets. Soluble oligomers are also produced along with aggregates in the reaction, as determined through size exclusion chromatography. Time-resolved and steady-state RET measurements reveal four dominant E20 conformations: (1) a partially collapsed conformation (24 Å donor,acceptor distance) in monomers, (2) an extended conformation in soluble oligomers (>29 Å donor,acceptor distance), (3) a minor partially collapsed conformation (22 Å donor-acceptor distance) in aggregates, and (4) a major highly collapsed conformation (13 Å donor,acceptor distance) in aggregates. These findings demonstrate the use of RET as a means of determining angstrom-level structural details of soluble oligomer and aggregated states of proteins. © 2009 Wiley Periodicals, Inc. Biopolymers 93: 299,317, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Effects of hydrophobicity and anions on self-assembly of the peptide EMK16-IIBIOPOLYMERS, Issue 4 2010Dawei Zou Abstract Effects of hydrophobic and electrostatic interactions on the self-assembling process of the ionic-complementary peptide EMK16-II are investigated by atomic force microscopy imaging, circular dichroism spectra, light scattering, and chromatography. It is found that the hydrophobicity of the peptide promotes the aggregation in pure water even at a very low concentration, resulting in a much lower critical aggregation concentration than that of another peptide, EAK16-II. The effect of anions in solution with different valences on electrostatic interactions is also important. Monovalent anions (Cl, and Ac,) with a proper concentration can facilitate the formation of peptide fibrils, with Cl, of smaller size being more effective than Ac, of larger size. However, only small amounts of fibrils, but plenty of large amorphous aggregates, are found when the peptide solution is incubated with multivalent anions, such as SO, C6H5O, and HPO. More importantly, by gel filtration chromatography, the citrate anion, which induces a similar effect on the self-assembling process of EMK16-II as that of SO and HPO, can interact with two or more positively charged residues of the peptide and reside in the amorphous aggregates. This implies a "salt bridge" effect of multivalent anions on the peptide self-assembling process, which can interpret a previous puzzle why divalent cations inhibit the formation of ordered nanofibrils of the ionic-complementary peptides. Thus, our results clarify the important effects of hydrophobic and electrostatic interactions on the self-assembling process of the ionic-complementary peptides. These are greatly helpful for us to understand the mechanism of peptides' self-assembling process and protein folding and aggregation. © 2009 Wiley Periodicals, Inc. Biopolymers 93: 318,329, 2010. This article was originally published online as an acceptedpreprint. The "Published Online" date corresponds to the preprintversion. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Heating-induced conformational change of a novel ,-(1,3)- D -glucan from Pleurotus geestanusBIOPOLYMERS, Issue 2 2010Mei Zhang Abstract Recently, we isolated and purified a neutral polysaccharide (PGN) from edible fungus Pleurotus geestanus. Its structure was characterized by a range of physical,chemical methods, including high performance anion exchange chromatography, uronic acid, and protein analyses, size exclusion chromatography with ultraviolet, refractive index and light scattering detectors, and nuclear magnetic resonance. Our results revealed that PGN is a novel ,-(1,3)- D -glucan with glucose attached to every other sugar residues at Position 6 in the backbone. It has a degree of branching of 1/2. Such structure is different from typical ,-(1,3)- D -glucans schizophyllan and lentinan in which DB is 1/3 and 2/5, respectively. Rheological study showed a very interesting melting behavior of PGN in water solution: heating PGN in water leads to two transitions, in the range of 8,12.5°C and 25,60°C, respectively. The melting behavior and conformational changes were characterized by rheometry, micro-differential scan calorimetry, atomic force microscopy, static and dynamic light scattering at different temperatures. The first heating-induced transition corresponds to the disintegration of polymer bundles into small helical clusters, resembling the heating-induced dissociation of SPG in water at 7°C; the second one might correspond to the dissociation of helical strands to individual chains. The ability of PGN to undergo a conformation/viscosity transition in water upon heating is very valuable to immobilize cells or enzymes or therapeutic DNA/RNA, which makes PGN a potentially useful biomaterial. © 2009 Wiley Periodicals, Inc. Biopolymers 93: 121,131, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Fluorescence spectroscopy of H-ras transfected murine fibroblasts: A comparison with Monte Carlo simulationsBIOPOLYMERS, Issue 2 2010Shlomo Mark Abstract Autofluorescence properties of tissues have been widely used to diagnose various types of malignancies. In this study, we measured the autofluorescence properties of H-ras transfected murine fibroblasts and the counterpart control cells. The pair of cells is genetically identical except for the transfected H-ras gene. We applied Monte Carlo simulations to evaluate the relative contributions of Rayleigh and Mie scattering effects towards fluorescence in an in vitro model system of normal and H-ras transfected fibroblasts. The experimental results showed that fluorescence emission intensity was higher for normal cells than the malignant counterpart cells by about 30%. In normal cells, linearity in emission intensity was observed for cell densities of up to 1.0 × 106 cells/ml whereas for transformed cells it was up to 1.4 × 106 cells/ml. Nuclear volume changes give good account for the differences in the intrinsic fluorescence between normal and malignant cells. The Monte Carlo (MC) code, newly developed for this study, explains both predominant experimental features: the large fluorescence intensity differences between the transfected and the corresponding control cells as well as the phenomena of the red shift in the excitation spectra as a function of cell density. The contribution of Rayleigh scattering was found to be predominant compared to Mie scattering. © 2009 Wiley Periodicals, Inc. Biopolymers 93: 132,140, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Revisiting the neighbor exclusion model and its applicationsBIOPOLYMERS, Issue 1 2010Marcio S. Rocha Abstract We review the neighbor exclusion model and some of its applications to analyze the binding data of DNA-ligand complexes. We revisit the closed form of the model developed by McGhee and von Hippel in 1974, showing that this classic model can be used to help studying the behavior of DNA contour and persistence lengths when interacting with intercalating ligands. We present methods to quantitatively analyze the variation of these two quantities, allowing one to determine important parameters of the interaction such as the intrinsic binding constant and the exclusion number of the ligand. © 2009 Wiley Periodicals, Inc. Biopolymers 93: 1,7, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] | ||||||||||||||||