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Several Peptides (several + peptide)
Selected AbstractsQuantitative peptidomics of mouse pituitary: comparison of different stable isotopic tagsJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 2 2005Fa-Yun Che Abstract Determining the relative levels of neuropeptides in two samples is important for many biological studies. An efficient, sensitive and accurate technique for relative quantitative analysis involves tagging the peptides in the two samples with isotopically distinct labels, pooling the samples and analyzing them using liquid chromatography/mass spectrometry (LC/MS). In this study, we compared two different sets of isotopic tags for analysis of endogenous mouse pituitary peptides: succinic anhydride with either four hydrogens or deuteriums and [3-(2,5-dioxopyrrolidin-1-yloxycarbonyl)propyl]trimethylammonium chloride with either nine hydrogens or deuteriums. These two labels react with amines and impart either a negative charge (succinyl) or a positive charge (4-trimethylammoniumbutyryl (TMAB)). Every endogenous mouse pituitary peptide labeled with the light TMAB reagent eluted from the C18 reversed-phase column at essentially the same time as the corresponding peptide labeled with the heavy reagent. Most of the peptides labeled with succinyl groups also showed co-elution of the heavy- and light-labeled forms on LC/MS. The mass difference between the heavy and light TMAB reagents (9 Da per label) was larger than that of the heavy and light succinyl labels (4 Da per label), and for some peptides the larger mass difference provided more accurate determination of the relative abundance of each form. Altogether, using both labels, 82 peptides were detected in Cpefat/fat mouse pituitary extracts. Of these, only 16 were detected with both labels, 41 were detected only with the TMAB label and 25 were detected only with the succinyl label. A number of these peptides were de novo sequenced using low-energy collisional tandem mass spectrometry. Whereas the succinyl group was stable to the collision-induced dissociation of the peptide, the TMAB-labeled peptides lost 59 Da per H9 TMAB group. Several peptides identified in this analysis represent previously undescribed post-translational processing products of known pituitary prohormones. In conclusion, both succinyl and TMAB isotopic labels are useful for quantitative peptidomics, and together these two labels provide more complete coverage of the endogenous peptides. Copyright © 2005 John Wiley & Sons, Ltd. [source] A novel tandem quadrupole mass spectrometer allowing gaseous collisional activation and surface induced dissociationJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 12 2001Shabaz Mohammed Abstract A novel tandem quadrupole mass spectrometer is described that enables gaseous collision-induced dissociation (CID) and surface-induced dissociation (SID) experiments. The instrument consists of a commercially available triple quadrupole mass spectrometer connected to an SID region and an additional, orthogonal quadrupole mass analyser. The performance of the instrument was evaluated using leucine-enkephalin, allowing a comparison between CID and SID, and with previous reports of other SID instruments. The reproducibility of SID data was assessed by replicate determinations of the collision energy required for 50% dissociation of leucine-enkephalin; excellent precision was observed (standard deviation of 0.6 eV) though, unexpectedly, the reproducibility of the equivalent figure for CID was superior. Several peptides were analysed using SID in conjunction with liquid secondary-ion mass spectrometry or electrospray; a comparison of the fragmentation of singly protonated peptide ions and the further dissociation of y-type fragments was consistent with the equivalence of the latter fragments to protonated peptides. Few product ions attributable to high-energy cleavages of amino acid side-chains were observed. The SID properties were investigated of a series of peptides differing only in the derivatization of a cysteine residue; similar decomposition efficiencies were observed for all except the cysteic acid analogue, which demonstrated significantly more facile fragmentation. Copyright © 2001 John Wiley & Sons, Ltd. [source] Influence of variations in sample handling on SELDI-TOF MS serum protein profiles for colorectal cancerPROTEOMICS - CLINICAL APPLICATIONS, Issue 6 2008Judith Y. M. N. Engwegen Abstract Sample handling can have a profound effect on serum protein profiles, challenging results obtained with archived sera under non-standardized sample collection. Here, we evaluate the influence of variations in sample handling on previous serum protein profiles for colorectal cancer (CRC) (Engwegen et al.,. World J. Gastroenterol. 2006, 12, 1536,1544). Sera were prospectively obtained from individuals with an indication for colonoscopy (n = 150: 65 controls, 52 adenomatous polyps, 29 CRC, 4 unknown), as well as from normal volunteers (n = 8). Protein profiles were acquired by SELDI-TOF MS on CM10 chips at pH 5. We assessed the influence of storage temperature, type of collection tube, coagulation temperature and freeze-thaw cycles on the serum protein profile. Several peptides occurred only in samples stored at ,20°C, indicating proteolytic degradation during storage. One was a previous CRC biomarker candidate, an N-terminal albumin fragment (m/z 3087), and two others complement C3f and a fragment thereof (m/z 2022 and 1863). Overall differences in protein profiles were also seen for different collection tubes, coagulation temperature and freeze-thaw cycles. However, three of five of our previously defined CRC biomarker candidates are stable to variations in the sample handling protocol, justifying their further validation in prospective studies. [source] A peek inside the neurosecretory brain through Orthopedia lensesDEVELOPMENTAL DYNAMICS, Issue 9 2008Luca Del Giacco Abstract The wealth of expression and functional data presented in this overview discloses the homeogene Orthopedia (Otp) as critical for the development of the hypothalamic neuroendocrine system of vertebrates. Specifically, the results depict the up-to-date portrait of the regulation and functions of Otp. The development of neuroendocrine nuclei relies on Otp from fish to mammals, as demonstrated for several peptide and hormone releasing neurons. Additionally, the activity of Otp is essential for the induction of the dopaminergic phenotype in the hypothalamus of vertebrates. Recent insights into the pathways required for Otp regulation have revealed the implication of the main extracellular signals acting during hypothalamic development. Alterations in these pathways are involved in several neuronal disorders, and the resultant downstream misregulation of Otp might impair the development of the hypothalamus, and be therefore responsible for the neuroendocrine dysfunctions that typify these diseases. Developmental Dynamics 237:2295,2303, 2008. © 2008 Wiley-Liss, Inc. [source] Gut,Brain Axis: Regulation of Glucose MetabolismJOURNAL OF NEUROENDOCRINOLOGY, Issue 12 2006A. C. Heijboer Obesity and type II diabetes mellitus have reached epidemic proportions. From this perspective, knowledge about the regulation of satiety and food intake is more important than ever. The gut releases several peptides upon feeding, which affect hypothalamic pathways involved in the regulation of satiety and metabolism. Within the hypothalamus, there are complex interactions between many nuclei of which the arcuate nucleus is considered as one of the most important hypothalamic centres that regulates food intake. The neuropeptides, which are present in the hypothalamus and are involved in regulating food intake, also play a key role in regulating glucose metabolism and energy expenditure. In synchrony with the effects of those neuropeptides, gastrointestinal hormones also affect glucose metabolism and energy expenditure. In this review, the effects of the gastrointestinal hormones ghrelin, cholecystokinin, peptide YY, glucagon-like peptide, oxyntomodulin and gastric inhibitory polypeptide on glucose and energy metabolism are reviewed. These gut hormones affect glucose metabolism at different levels: by altering food intake and body weight, and thereby insulin sensitivity; by affecting gastric delay and gut motility, and thereby meal-related fluctuations in glucose levels; by affecting insulin secretion, and thereby plasma glucose levels, and by affecting tissue specific insulin sensitivity of glucose metabolism. These observations point to the notion of a major role of the gut,brain axis in the integrative physiology of whole body fuel metabolism. [source] Synthesis and use of a pseudo-cysteine for native chemical ligationJOURNAL OF PEPTIDE SCIENCE, Issue 4 2003David A. Alves Abstract The process of native chemical ligation (NCL) is well described in the literature. An N -terminal cysteine-containing peptide reacts with a C -terminal thioester-containing peptide to yield a native amide bond after transesterification and acyl transfer. An N -terminal cysteine is required as both the N -terminal amino function and the sidechain thiol participate in the ligation reaction. In certain circumstances it is desirable, or even imperative, that the N -terminal region of a peptidic reaction partner remain unmodified, for instance for the retention of biological activity after ligation. This work discusses the synthesis of a pseudo- N -terminal cysteine building block for incorporation into peptides using standard methods of solid phase synthesis. Upon deprotection, this building block affords a de factoN -terminal cysteine positioned on an amino acid sidechain, which is capable of undergoing native chemical ligation with a thioester. The syntheses of several peptides and structures containing this motif are detailed, their reactions discussed, and further applications of this technology proposed. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd. [source] Peptide-based radiopharmaceuticals: Future tools for diagnostic imaging of cancers and other diseasesMEDICINAL RESEARCH REVIEWS, Issue 3 2004S.M. Okarvi Abstract An Erratum has been published for this article in Medicinal Research Reviews 2004;24:685,686. Small synthetic receptor-binding peptides are the agents of choice for diagnostic imaging and radiotherapy of cancers due to their favorable pharmacokinetics. Molecular modification techniques permit the synthesis of a variety of bioactive peptides with chelating groups, without compromising biological properties. Various techniques have been developed that allow efficient and site-specific labeling of peptides with clinically useful radionuclides such as 99mTc, 123I, 111In, and 18F. Among them, 99mTc is the radionuclide of choice because of its excellent chemical and imaging characteristics. Recently, many 99mTc-labeled peptides have proven to be useful imaging agents. Beside 99mTc-labeled peptides, several peptides radiolabeled with 111In and 123I have been prepared and characterized. In addition, 18F-labeled peptides hold clinical potential due to their ability to quantitatively detect and characterize a variety of human diseases using positron-emission tomography. The availability of this wide range of peptides labeled with different radionuclides offers multiple diagnostic and therapeutic applications. Various receptors are over-expressed in particular tumor types and peptides binding to these receptors can be used to visualize tumor lesions scintigraphically. Thus, radiolabeled peptides have potential use as carriers for the delivery of radionuclides to tumors, infarcts, and infected tissues for diagnostic imaging and radiotherapy. Many radiolabeled peptides are currently under investigation to determine their potential as imaging agents. These peptides are designed mainly for thrombus, tumor, and infection/inflammation imaging. This article presents recent developments in small synthetic peptides for imaging of thrombosis, tumors, and infection/inflammation. © 2004 Wiley Periodicals, Inc. Med Res Rev, 24, No. 3, 357,397, 2004 [source] Determination of angiotensin-I converting enzyme inhibitory peptides in chicken leg bone protein hydrolysate with alcalaseANIMAL SCIENCE JOURNAL, Issue 1 2009Fu-Yuan CHENG ABSTRACT This study aims to identify peptides with angiotensin-I converting enzyme (ACE) inhibitory activity in hydrolysate from chicken leg bone protein hydrolyzed with alcalase for 4 h (A4H). The hydrolysate has demonstrated potent in vitro ACE inhibitory activity, and has been shown to attenuate the development of hypertension and cardiovascular hypertrophy in spontaneously hypertensive rats (SHR). A4H is competitive for ACE and was separated using high-performance liquid chromatography (HPLC) with a gel filtration column (Superdex Peptide HR 10/30). The results show that A4H is a mixed non-competitive inhibitor. Eighteen fractions were detected after separation of A4H, and most of them showed ACE inhibitory activity. Five fractions with strong ACE inhibitory activities (above 50%) were labeled from A to E. In addition, there were 10 peptides, consisting of 5,10 amino acid residues that were identified from fraction D that exhibited the strongest ACE inhibitory activity. Three of the identified peptides corresponded to peptides derived from collagen type I and chicken muscular protein. It is revealed that A4H has several peptides that possess ACE inhibitory activities. [source] Structure of the ligand-binding domain of the EphB2 receptor at 2,Å resolutionACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 2 2009Yehuda Goldgur Eph tyrosine kinase receptors, the largest group of receptor tyrosine kinases, and their ephrin ligands are important mediators of cell,cell communication regulating cell attachment, shape and mobility. Recently, several Eph receptors and ephrins have also been found to play important roles in the progression of cancer. Structural and biophysical studies have established detailed information on the binding and recognition of Eph receptors and ephrins. The initial high-affinity binding of Eph receptors to ephrin occurs through the penetration of an extended G,H loop of the ligand into a hydrophobic channel on the surface of the receptor. Consequently, the G,H loop-binding channel of Eph receptors is the main target in the search for Eph antagonists that could be used in the development of anticancer drugs and several peptides have been shown to specifically bind Eph receptors and compete with the cognate ephrin ligands. However, the molecular details of the conformational changes upon Eph/ephrin binding have remained speculative, since two of the loops were unstructured in the original model of the free EphB2 structure and their conformational changes upon ligand binding could consequently not be analyzed in detail. In this study, the X-ray structure of unbound EphB2 is reported at a considerably higher 2,Å resolution, the conformational changes that the important receptor loops undergo upon ligand binding are described and the consequences that these findings have for the development of Eph antagonists are discussed. [source] Selection and mass spectrometry characterization of peptides targeting semiconductor surfacesBIOTECHNOLOGY & BIOENGINEERING, Issue 6 2009Elias Estephan Abstract We report on elaboration of 12-mer peptides that reveal specific recognition for the following semiconductor (SC) surfaces: GaAs(100), InAs(100), GaN(0001), ZnSe(100), ZnTe(100), GaAs(111)A, GaSb(100), CdSe(100). A M13 bacteriophage library was used to screen 109 different 12-mer peptides against these substrates to finally isolate, in maximum six amplification cycles, peptides that bind to the target surfaces. The specific peptides for the InAs and ZnSe surfaces were obtained. Contrary, for the other SC surfaces several peptides with high affinities have been isolated. Aiming for a better specificity, when the phage display has been conducted through six cycles, the screening procedure got dominated by a phage present in the M13 bacteriophage library and the SVSVGMKPSPRP peptide has been selected for different SCs. The high amplification potential of this phage has been observed previously with different targets. Thus, precaution should be undertaken in defining adhesion peptides with the phage display technique and real affinity of the obtained biolinkers should be studied with other methods. We employed mass spectrometry (MALDI-TOF/TOF) to demonstrate the preferential attachment (or not) of the SVSVGMKPSPRP peptide to the different SC surfaces. This allows us to define a realistic selection of the expressed peptides presenting affinity for the studied eight SC surfaces. We demonstrate that with increasing the dielectric constants of the employed solvents, adhesion of the SVSVGMKPSPRP peptide onto GaN(0001) is hindered. Biotechnol. Bioeng. 2009; 104: 1121,1131. © 2009 Wiley Periodicals, Inc. [source] | |||||||||||||