ISSN:1075-2617    

DOI:10.1002/psc.310010102

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractAll efforts to turn the ultimate goal in proteinde novodesign into reality–the construction of new macromolecules with predetermined three‐dimensional structure and well‐defined functionality–failed because the mechanism of folding has still to be unravelled. In the present review, various attempts to apply synthetic tools for inducing native‐like structural features in peptides in order to bypass the folding problem are described. Besides well‐established methods for the nucleation and stabilization of secondary structures, e.g. α‐helices, β‐sheets and β‐turns, topological templates as ‘built‐in’ folding devices have more recently become the key elements for the induction of protein‐like folding units (template‐assembled synthetic proteins, TASP). Progress in the synthetic strategy and structural characterization of this new type of macromolecules opens the way for the desig

ISSN:1075-2617    

DOI:10.1002/psc.310010103

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

Abstract2‐Hydroxy‐4‐methoxybenzyl‐amino acid residues inhibit interchain association in solid phase peptide synthesis. They are easily introduced through theirN,O‐bisFmoc derivatives. Preparation of a range of these derivatives is

ISSN:1075-2617    

DOI:10.1002/psc.310010104

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractBy introducing a new operation (non‐coupling), our portioning–mixing method has become suitable for preparing binary peptide libraries. We demonstrate that all the expected components of a simple library are present in the mixture. The number of components in such libraries, the molar ratio of peptides as well as the possibilities of screening are discus

ISSN:1075-2617    

DOI:10.1002/psc.310010105

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThree types of beaded polyethylene glycol polyacrylamide copolymers (PEGA) with a high content of polyethylene glycol (PEG) were synthesized by inverse suspension polymerization and characterized for peptide synthesis and with respect to their physical properties. Several peptides of high purity have been synthesized on the resin. The properties which were determined were loading of amino group, swelling, bead size distribution, porosity, flexibility and compatibility with active biomolecules. A loading of 0.35 mmol/g has been obtained and the swelling was excellent in solvents of various polarities ranging from water to dichloromethane. The13C‐NMRT1‐relaxation times of a resin containing a peptide were determined in DMSO‐d6and the resin was found to exhibit a behaviour similar to the components in free sol

ISSN:1075-2617    

DOI:10.1002/psc.310010106

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractA variety of hostL‐alanine homo‐peptides (to the pentamer) containing one or two spin‐labelled TOAC (2,2,6,6‐tetramethylpiperidine‐1‐oxyl‐4‐amino‐4‐carboxylic acid) residues were synthesized by solution methods and fully characterized. The conformational features of the terminally blocked, doubly spin‐labelled–TOAC–(Ala)2–TOAC–Ala– pentapeptide were examined in the crystal state by X‐ray diffraction and in solution using a combination of techniques (Fourier transform infrared, circular dichroism, cyclic voltammetry and electron spin resonance) in comparison with singly labelled shorter peptides. The 310‐helical structure of the pentapeptide, promoted by the two Cα,α‐disubstituted glycines under favourable experimental conditions, allows an interaction to take place between the two nitroxide TOAC side chains spaced by one turn of the helix. Taken together, these results suggest that TOAC is an excellent probe for exploring bends

ISSN:1075-2617    

DOI:10.1002/psc.310010107

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractAn analogue of human melanin‐concentrating hormone (MCH) suitable for radioiodination was designed in which Tyr13and Val19of the natural peptide were replaced by phenylalanyl and tyrosyl residues: [Phe13, Tyr19] ‐MCH. The peptide was synthesized by the continuous‐flow solid‐phase methodology using Fmocstrategy and Polyhipe PA 500 and PEG‐PS resins. The linear MCH peptides with either acetamidomethyl‐protected or free cysteinyl residues were purified to homogeneity and cyclized by iodine oxidation, yielding the final product with the correct molecular weight of 2434.61. Radioiodination of the C‐terminal tyrosine was carried out enzymatically using solid‐phase bound glucose oxidase/lactoperoxidase, followed by purification on a reversed‐phase mini‐column and by high‐pressure liquid chromatography. The resulting [125I]‐[Phe13, Tyr19]‐MCH tracer was the first radiolabelled MCH peptide suitable for radioreceptor assay: saturation binding analysis using mouse G4F‐7 melanoma cells demonstrated the presence of 1090 MCH receptors per cell. The dissociation constant (KD) was 1.18 × 10−10M, indicating high‐affinity MCH receptors on these cells. MCH receptors were also found in other cell lines such as mouse B16‐F1 and G4F and human RE melanoma cells as well as in PC12 and COS‐7 cells. Competition binding analyses with a number of other peptides such as α‐MSH, neuropeptide Y, substance P and pituitary adenylate cyclase activating peptide, demonstrated that the binding to the MCH receptor is specific. Atrial natriuretic factor was found to be a weak competitor of MCH, indicating topological similarities between MCH and

ISSN:1075-2617    

DOI:10.1002/psc.310010108

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractWe have investigated the effects of mono‐substitutions with the conformationally restricted amino acid, 1,2,3,4 tetrahydroisoquinoline‐3‐carboxylic acid (Tic) at position 3 in arginine vasopressin (AVP), at positions 2, 3 and 7 in potent non‐selective cyclic AVP V2/V1aantagonists, in potent and selective cyclic and linear AVP V1aantagonists, in a potent and selective oxytocin antagonist and in a new potent linear oxytocin antagonist Phaa‐D‐Tyr(Me)‐Ile‐Val‐Asn‐Orn‐Pro‐Orn‐NH2(10). We report here the solid‐phase synthesis of peptide 10 together with the following Tic‐substituted peptides: 1, [Tic3]AVP; 2, d(CH2)5[D‐Tic2]VAVP; 3, d(CH2)5[D‐Tyr(Et)2Tic3]VAVP; 4, d(CH2)5[Tic2Ala‐NH29]AVP; 5, d(CH2)5[Tyr(Me)2, Tic3, Ala‐NH29]AVP; 6, d(CH2)5[Tyr(Me)2, Tic7]AVP; 7, Phaa‐D‐Tyr(Me)‐Phe‐Gln‐Asn‐Lys‐Tic‐Arg‐NH2; 8, desGly‐NH2,d(CH2)5[Tic2,Thr4]OVT; 9, desGly‐NH2d(CH2)5[Tyr(Me)2Thr4, Tic7]OVT; 11, Phaa‐D‐Tic‐Ile‐Val‐Asn‐Orn‐Pro‐Orn‐NH2, using previously described methods. The protected precursors were synthesized by the solid‐phase method, cleaved, purified and deblocked with sodium in liquid ammonia to give the free peptides 1–11 which were purified by methods previously described. Peptides 1–11 were examined for agonistic and antagonistic potency in oxytocic (in vitro, without Mg2+) and AVP antidiuretic (V2‐receptor) and vasopressor (V1a‐receptor) assays. Tic3substitution in AVP led to drastic losses of V2, V1aand oxytocic agonistc activities in peptide 1.L‐ andD‐Tic2substitutions led to drastic losses of anti‐V2/anti‐V1aand anti‐oxytocic potencies in peptides 2, 4, 8 and 11 (peptide 2 retained substantial anti‐oxytocic potency; pA2= 7.25 ± 0.25). Whereas Tic3substitution in the selective V1aantagonist d(CH2)5[Tyr(Me)2, Ala‐NH29]APV(C) led to a drastic reduction in anti‐V1apotency (from anti‐V1apA2) 8.75 to 6.37 for peptide 5, remarkably, Tic3substitution in the V2/V1aantagonist d(CH2)5[D‐Tyr(Et)2]VAVP(B) led to full retention of anti‐V2potency and a 95% reduction in anti‐V1apotency. With an anti‐V2pA2= 7.69 ± 0.05 and anti‐V1apA2= 6.95 ± 0.03, d(CH2)5[D‐Tyr(Et)2,Tic3]VAVP exhibits a 13‐fold gain in anti‐V2/anti‐V1aselectivity compared to (B). Tic7substitutions are very well tolerated in peptides 6, 7 and 9 with excellent retention of the characteristic potencies of the parent peptides. The findings on the effects of Tic3substitutions reported here may provide promising leads to the design of more selective and possibly orally active V2antagonists for use as pharmacological tools and a

ISSN:1075-2617    

DOI:10.1002/psc.310010109

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe multipin method of peptide synthesis is demonstrated as a potent methodological tool, where large numbers of comparative studies can be performed concurrently. Two studies are presented. In each study, the test peptides were simultaneously synthesized, and the products examined by high throughput ion spray mass spectrometry and reverse‐phase HPLC. In the first study, comprising 24 experiments, peptides1(AELFSTHYLAFKEDYSQ‐NH2) and2(LKDFRVYFREGRDQLWKGPG‐NH2) were prepared using Fmoc‐Axx/BOP/HOBt/NMM (100: 100: 100: 150 mM) and Fmoc‐Axx/HATU/HOAt/NMM (100: 100: 100: 150 mM) with 60.90 and 120 min coupling times. The two reagent combinations were found to give comparable results. The second study compared the N‐terminal coupling of Fmoc‐Asn‐OH, Fmoc‐Asn(Mbh)‐OH, Fmoc‐Asn(Mtt)‐OH, Fmoc‐Asn(Tmob)‐OH and Fmoc‐Asn(Trt)‐OH in the synthesis of seven test peptides:3, NVQAAIDYIG‐cyclo(Kp);4, NTVQAAIDYIG‐cyclo(KF);5, NRVYVHPFNL;6, NRVYVHPFHL:7, NEAYVHDAPVRSLN:8, NQLVVPSEGLYLIYSQVLFK.9, NPNANPNANPNA. A total of 33 experiments were performed. Peptides3and4were selected to highlight the effect of steric bulk of each Asn derivative on coupling efficiency. Reagent efficiency, as measured by target peptide purity, was as follows: Fmoc‐Asn(Tmob)‐OH>Fmoc‐Asn‐OH>Fmoc‐As

ISSN:1075-2617    

DOI:10.1002/psc.310010110

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

ISSN:1075-2617    

DOI:10.1002/psc.310010101

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY