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Linear Analog (linear + analog)
Selected AbstractsModeling an active conformation for linear peptides and design of a competitive inhibitor for HMG-CoA reductaseJOURNAL OF MOLECULAR RECOGNITION, Issue 4 2008Valeriy V. Pak Abstract This study presents an approach that can be used to search for lead peptide candidates, including unconstrained structures in a recognized sequence. This approach was performed using the design of a competitive inhibitor for 3-hydroxy-3-methylglutaryl CoA reductase (HMGR). In a previous design for constrained peptides, a head-to-tail cyclic structure of peptide was used as a model of linear analog in searches for lead peptides with a structure close to an active conformation. Analysis of the conformational space occupied by the peptides suggests that an analogical approach can be applied for finding a lead peptide with an unconstrained structure in a recognized sequence via modeling a cycle using fixed residues of the peptide backbone. Using the space obtained by an analysis of the bioactive conformations of statins, eight cyclic peptides were selected for a peptide library based on the YVAE sequence as a recognized motif. For each cycle, the four models were assessed according to the design criterion ("V" parameter) applied for constrained peptides. Three cyclic peptides (FGYVAE, FPYVAE, and FFYVAE) were selected as lead cycles from the library. The linear FGYVAE peptide (IC50,=,0.4,µM) showed a 1200-fold increase the inhibitory activity compared to the first isolated LPYP peptide (IC50,=,484,µM) from soybean. Experimental analysis of the modeled peptide structures confirms the appropriateness of the proposed approach for the modeling of active conformations of peptides. Copyright © 2008 John Wiley & Sons, Ltd. [source] New Second-Order Nonlinear Optical Polymers Derived from AB2 and AB Monomers via Sonogashira Coupling ReactionMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 8 2010Zhong'an Li Abstract In this paper, a facile route was designed to prepare a new AB2 -type polymer P1 via simple Sonogashira coupling reaction, also its corresponding linear analog (P2) was obtained from AB monomer for comparison. Despite the relatively lower loading density of the effective chromophore moieties, P1 demonstrated higher second-harmonic coefficient (153.9,pm,·,V,1) than that of P2 (98.2,pm,·,V,1), due to the three-dimensional spatial isolation effect of the hyperbranched structure. The good results of P2 also indicated that the ladder shape may help to solve the problem existing in main-chain polymers, the low poling efficiency. [source] Synthesis, Sequential Crystallization and Morphological Evolution of Well-Defined Star-Shaped Poly(, -caprolactone)- b -poly(L -lactide) Block Copolymer,MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 5 2006Jing-Liang Wang Abstract Summary: Well-defined star-shaped poly(, -caprolactone)- b -poly(L -lactide) copolymers (PCL- b -PLLA) were synthesized via sequential block copolymerization, and their molecular weights and arm length ratio could be accurately controlled. Both differential scanning calorimetry and wide angle X-ray diffraction analysis indicated that the crystallization of both the PLLA and PCL blocks within the star-shaped PCL- b -PLLA copolymer could be adjusted from the arm length of each block, and both blocks mutually influenced each other. The sequential isothermal crystallization process of both the PLLA and PCL blocks within the PCL- b -PLLA copolymers was directly observed with a polarized optical microscope, and the isothermal crystallization of the PCL segments was mainly templated by the existing spherulites of PLLA. Moreover, the PLLA blocks within the star-shaped PCL- b -PLLA copolymer progressively changed from ordinary spherulites to banded spherulites when the arm length ratio of PCL to PLLA was increased while concentric spherulites were observed for the linear analog. Significantly, these novel spherulites with concentric or banded textures and the morphological evolution of the spherulites have been observed for the first time in the PCL- b -PLLA block copolymers. [source] Water-soluble, thermoresponsive, hyperbranched copolymers based on PEG-methacrylates: Synthesis, characterization, and LCST behaviorJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2010Mario Luzon Abstract A series of water-soluble thermoresponsive hyperbranched copoly(oligoethylene glycol)s were synthesized by copolymerization of di(ethylene glycol) methacrylate (DEG-MA) and oligo(ethylene glycol) methacrylate (OEG-MA, Mw = 475 g/mol), with ethylene glycol dimethacrylate (EGD-MA) used as the crosslinker, via reversible addition fragmentation chain transfer polymerization. Polymers were characterized by size exclusion chromatography and nuclear magnetic resonance analyses. According to the monomer composition, that is, the ratio of OEG-MA: DEG-MA: EGD-MA, the lower critical solution temperature (LCST) could be tuned from 25 °C to 90 °C. The thermoresponsive properties of these hyperbranched copolymers were studied carefully and compared with their linear analogs. It was found that molecular architecture influences thermoresponsive behavior, with a decrease of around 5,10 °C in the LCST of the hyperbranched polymers compared with the LCST of linear chains. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2783,2792, 2010 [source] | ||||||||||