摘要:

Spider silk is the toughest known biomaterial and even outrivals modern synthetic high‐performance materials. The question of understanding fiber formation is how the spider can prevent premature and fatal aggregation processes inside its own body and how the chemical and mechanical stimuli used to induce the fiber formation process translate into structural changes of the silk material, finally leading to controlled and irreversible aggregation. Here, the focus will be on the structure and function of the highly conserved N‐domains and C‐terminal domains of spider dragline silk which, unlike the very long repetitive sequence elements, adopt a folded conformation in solution and are therefore able to control intermolecular interactions and aggregation between other spider silk molecules. The structures of these domains add valuable details for the construction of a molecular picture of the complicated and highly optimized silk assembly process that might be beneficial for large‐scalein vitrofiber formation attempts with recombinant silk material. Copyright © 2012 European Peptide Society and John Wiley&S

ISSN:1075-2617    

DOI:10.1002/psc.2417

出版商:John Wiley&Sons, Ltd    

年代:2012

数据来源: WILEY

摘要:

Antimicrobial peptides (AMPs) have recently gained attention as potentially valuable diagnostic and therapeutic agents. The utilization of these peptides for diagnostic purposes relies on the ability to immobilize them on the surface of a detection platform in a predictable and reliable manner that facilitates target binding. The method for attachment of peptides to a solid support is guided by peptide length, amino acid composition, secondary structure, and the nature of the underlying substrate. While immobilization methods that target amine groups of amino acid sequences are widely used, they can result in heterogeneous conjugation at multiple sites on a peptide and have direct implications for peptide presentation and function. Using two types of commercial amine‐reactive microtiter plates, we described the effects of analogous immobilization chemistries on the surface attachment of AMPs and their differential binding interaction with Gram‐specific bacterial biomarkers, lipopolysaccharide and lipoteichoic acid. As might be expected, differences in overall binding affinities were noted when comparing AMPs immobilized on the two types of plates. However, the two‐amine‐targeted linking chemistries also affected the specificity of the attached peptides; lipopolysaccharide generally demonstrated a preference for peptides immobilized on one type of plate, while (when observed at all) lipoteichoic acid bound preferentially to AMPs immobilized on the other type of plate. These results demonstrate the potential for tuning not only the binding affinities but also the specificities of immobilized AMPs by simple alterations in linking strategy. Published 2012. This article is a U.S. Government work and is in the public domain in

ISSN:1075-2617    

DOI:10.1002/psc.2399

出版商:John Wiley&Sons, Ltd    

年代:2012

数据来源: WILEY

摘要:

Humanin (HN) is a linear 24‐aa peptide recently detected in human Alzheimer's disease (AD) brain. HN specifically inhibits neuronal cell deathin vitroinduced by ß‐amyloid (Aß) peptides and by amyloid precursor protein and its gene mutations in familial AD, thereby representing a potential therapeutic lead structure for AD; however, its molecular mechanism of action is not well understood. We report here the identification of the binding epitopes between HN and Aß(1–40) and characterization of the interaction structure through a molecular modeling study. Wild‐type HN and HN‐sequence mutations were synthesized by SPPS and the HPLC‐purified peptides characterized by MALDI‐MS. The interaction epitopes between HN and Aß(1–40) were identified by affinity‐MS using proteolytic epitope excision and extraction, followed by elution and mass spectrometric characterization of the affinity‐bound peptides. The affinity‐MS analyses revealed HN(5–15) as the epitope sequence of HN, whereas Aß(17–28) was identified as the Aß interaction epitope. The epitopes and binding sites were ascertained by ELISA of the complex of HN peptides with immobilized Aß(1–40) and by ELISA with Aß(1–40) and Aß‐partial sequences as ligands to immobilized HN. The specificity and affinity of the HN‐Aß interaction were characterized by direct ESI‐MS of the HN‐Aß(1–40) complex and by bioaffinity analysis using a surface acoustic wave biosensor, providing aKDof the complex of 610 nm. A molecular dynamics simulation of the HN‐Aß(1–40) complex was consistent with the binding specificity and shielding effects of the HN and Aß interaction epitopes. These results indicate a specific strong association of HN and Aß(1–40) polypeptide and provide a molecular basis for understanding the neuroprotective function of HN. Copyr

ISSN:1075-2617    

DOI:10.1002/psc.2404

出版商:John Wiley&Sons, Ltd    

年代:2012

数据来源: WILEY

摘要:

The identification of leptin as a mediator of body weight regulation provided much initial excitement for the treatment of obesity. Unfortunately, leptin monotherapy is insufficient in reversing obesity in rodents or humans. Recent findings suggest that amylin is able to restore leptin sensitivity and when used in combination with leptin enhances body weight loss in obese rodents and humans. However, as the uniqueness of this combination therapy remains unclear, we assessed whether co‐administration of leptin with other weight loss‐inducing hormones equally restores leptin responsiveness in diet‐induced obese (DIO) mice. Accordingly, we report here the design and characterization of a series of site‐specifically enhanced leptin analogs of high potency and sustained action that, when administered in combination with exendin‐4 or fibroblast growth factor 21 (FGF21), restores leptin responsiveness in DIO mice after an initial body weight loss of 30%. Using either combination, body weight loss was enhanced compared with either exendin‐4 or FGF21 monotherapy, and leptin alone was sufficient to maintain the reduced body weight. In contrast, leptin monotherapy proved ineffective when identical weight loss was induced by caloric restriction alone over a comparable time. Accordingly, we find that a hypothalamic counter‐regulatory response to weight loss, assessed using changes in hypothalamic agouti related peptide (AgRP) levels, is triggered by caloric restriction, but blunted by treatment with exendin‐4. We conclude that leptin re‐sensitization requires pharmacotherapy but does not appear to be restricted to a unique signaling pathway. Our findings provide preclinical evidence that high activity, long‐acting leptin analogs are additively efficacious when used in combination with other weight‐lowering agents. Copyright © 2012 European Peptide Society an

ISSN:1075-2617    

DOI:10.1002/psc.2408

出版商:John Wiley&Sons, Ltd    

年代:2012

数据来源: WILEY

摘要:

A peptide SPOT array was synthesized on a glass chip and used to determine protease subsite preference. To synthesize a peptide array for positional scanning, the ratio of the isokinetic concentration was determined for every Fmoc‐amino acid except Cys. Based on this ratio, a peptide array consisting of Dabcyl‐X‐X‐P2‐Arg‐X‐X‐X‐Lys(FITC) (X: equimolar mixture of 19 amino acids, P2: one of 19 amino acids) was synthesized on a chitosan‐grafted glass chip. Subsequently, the peptide substrates on the array were hydrolyzed by thrombin to screen for subsite specificity using a fluorescence quenching‐based assay. The P2subsite specificity of thrombin was screened by the fluorescence images obtained after hydrolysis. Pro at the P2subsite showed the highest specificity for thrombin based on both the fluorescence quenching‐based assay and the solution phase assay. From these results, we confirmed that our mixture‐based peptide SPOT array format on the chitosan‐grafted glass chips could be used to determine protease subsite preference. Copyright © 2012 European Peptide Soci

ISSN:1075-2617    

DOI:10.1002/psc.2409

出版商:John Wiley&Sons, Ltd    

年代:2012

数据来源: WILEY

摘要:

The influence of lithium cations on thecis/transisomerization of prolyl peptide bonds was investigated in a quantitative manner in trifluoroethanol (TFE) and acetonitrile, employing NMR techniques. The focus was on various environmental and structural aspects, such as lithium cation and water concentrations, the type of the partner amino acid in the prolyl peptide bond, and the peptide sequence length.Comparison of the thermodynamic parameters of the isomerization in LiCl/TFE and TFE shows a lithium cation concentration dependence of thecis/transratio, which saturates at cation concentrations>200 mM. A pronounced increase in thecisisomer content in the presence of lithium cations occurs with the exception of peptides with Gly‐Pro and Asp‐Pro moieties. The cation effect appears already at the dipeptide level. The salt concentration can considerably be reduced in solvents with a lower number of nucleophilic centers like acetonitrile. The lithium cation effect decreases with small amounts of water and disappears at a water concentration of about 5%. The isomerization kinetics under the influence of lithium cations suggests a weak cation interaction with the carbonyl oxygen of the peptide bond. Copyright © 2012 European Peptide Society and John Wiley&Son

ISSN:1075-2617    

DOI:10.1002/psc.2410

出版商:John Wiley&Sons, Ltd    

年代:2012

数据来源: WILEY

摘要:

Control of gross morphology of soft matter remains an area of continued interest. Towards this goal, this paper describes conjugation of mannose residues and introduction of thiol functionalities to diphenylalanine (FF) dipeptide, a fibrillating motif from amyloid‐β peptide, as covalent modifiers of its solution‐phase self‐assembly process. It was found that covalent attachment of a single mannose residue to FF leads to the retention of tubular structures, whereas the conjugation of two mannose units, linked through a Lys residue, resulted in a dramatic change from tubular morphology to spherical structures. However, a similar switch to spherical objects could be achieved by introducing a thiol residue in the mono‐mannosylated FF dipeptide. Interestingly, these glycopeptides also exhibited interaction with concanavalin A, thereby providing an indirect evidence for the availability of mannose units for the process of lectin‐carbohydrate interaction in the self‐organized state. Copyright © 2012 European Peptide Society and John Wi

ISSN:1075-2617    

DOI:10.1002/psc.2411

出版商:John Wiley&Sons, Ltd    

年代:2012

数据来源: WILEY

摘要:

We have previously shown that a recombinant human PTH fragment, Pro‐Pro‐[Arg11] hPTH (1–34)‐Pro‐Pro‐Asp (hPTH′), could be a potentially better and more cost‐effective therapeutic agent than PTH (1–34) on osteoporosis. In this report, we characterized the solution conformations of hPTH′ by NMR spectroscopy and modeled the interactions between the hPTH′ and the PTH receptor. By comparing it with PTH (1–34) structures and their respective interactions with the PTH receptor, we identified two segments of helix extending from Ile5 to Met8 and from Glu22 to Gln29 with a divided kink between the two helixes around Arg20. Mutated arginine makes hPTH′ fill the receptor cavity better as well as forms hydrogen bonds with Val193. Understanding the ligand receptor interactions will help us design small molecules to better mimic the activities of PTH. Copyright © 2012 European Peptide Societ

ISSN:1075-2617    

DOI:10.1002/psc.2412

出版商:John Wiley&Sons, Ltd    

年代:2012

数据来源: WILEY

摘要:

In the present study, we report synthesis and biological evaluation of theN‐Boc‐protected tripeptides4a–landN‐For protected tripeptides5a–las new For‐Met‐Leu‐Phe‐OMe (fMLF‐OMe) analogues. All the new ligands are characterized by theC‐terminal Phe residue variously substituted at position 4 of the aromatic ring. The agonism of5a–land the antagonism of4a–l(chemotaxis, superoxide anion production, lysozyme release as well as receptor binding affinity) have been examined on human neutrophils. No synthesized compounds has higher activity than the standard fMLF‐OMe tripeptide to stimulate chemotaxis, although compounds5aand5cwith ‐CH3and ‐C(CH3)3, respectively, in position 4 on the aromatic ring, are better than the standard tripeptide to stimulate the production of superoxide anion, in higher concentration. Compounds4fand4i, containing ‐F and ‐I in position 4, respectively, on the aromatic ring of phenylalanine, exhibit significant chemotactic antagonism. The influence of the different substitution at the position 4 on the aromatic ring of phenylalanine is discussed. Copyright © 2012 European Pept

ISSN:1075-2617    

DOI:10.1002/psc.2414

出版商:John Wiley&Sons, Ltd    

年代:2012

数据来源: WILEY