摘要:

AbstractChromatographic separation of rat brain extracts followed by automatic Edman sequencing of the major individual components resulted in identification of 61 endogenous peptides derived from known functional proteins (hemoglobin, myelin basic protein, cytochrome‐coxidase, etc.) or unknown precursors. The results are compared with the data obtained earlier for bovine brain. Although the sequences of bovine and rat hemoglobin contain about 20% of amino acid substitutions, the families of structurally related peptides are very similar in both extracts. Several other proteins also give rise to identical or closely related peptide fragments in the two mammalian species. The outlined similarity extends almost exclusively to the most abundant peptides present in the extracts. The minor components show less overlap. Four hemoglobin‐derived peptides isolated from rat brain were shown to be biologically active in tumor cells. Eleven are identical to bioactive peptides from other species. Ten structurally overlap with bioactive peptides from other sources. The data obtained show similar biosynthetic pathways of pool components in different species, the resultant peptides being aimed at fulfilling related functions. Copyright © 2000 European Peptide Society and John Wiley&Sons,

ISSN:1075-2617    

DOI:10.1002/1099-1387(200008)6:8<345::AID-PSC258>3.0.CO;2-U

出版商:John Wiley&Sons, Ltd.    

年代:2000

数据来源: WILEY

摘要:

AbstractThe mechanisms of reactions causing irreversible inhibition of the activity of enzymes when irradiated in the presence of the recently developed α‐methyl‐6‐nitroveratryl‐based photolinker [Holmes CP.J. Org. Chem.1997;62: 2370–2380] have been investigated. Several experiments based on the interaction of the photolinker with model peptides orn‐butylamine have been accomplished. A complexity of products, resulting from the side reactions competing with the ‘normal’ photocleavage of the linker, have been found. The amino and thiol groups of the molecules present in the solvents upon irradiation were recognized as having a major influence on the course of photolysis. Some of these side products resulting from the interaction with amines were identified and the mechanisms by which they can be generated are discussed. The mechanism of the interaction of the thiol groups present in peptides or proteins with the photolinker is unclear and it remains to be further elucidated. It was found that the undesirable effects are favored by a basic pH and are largely reduced by a slightly acidic pH, together with the presence of dithiothreitol. Significant positive effects of dithiothreitol have been observed on the rate as well as the yield of the photocleavage. These results demonstrate that the use of photolabile linkers in biological media can be accompanied by undesired effects, which can be largely reduced by choosing appropriate conditions and additives. Copyright © 2000 European Peptide Society and Joh

ISSN:1075-2617    

DOI:10.1002/1099-1387(200008)6:8<355::AID-PSC261>3.0.CO;2-C

出版商:John Wiley&Sons, Ltd.    

年代:2000

数据来源: WILEY

摘要:

AbstractThe capability of Glu/Asp‐specific endopeptidase fromBacillus licheniformisto form Glu/Asp‐Xaa bonds in frozen aqueous systems was investigated. Under frozen state conditions, the enzyme was able to catalyse peptide bond formation more effectively than in liquid reaction mixtures. The acceptance of amino components which were completely inefficient nucleophiles at room temperature indicates a changed specificity of Glu/Asp‐specific endopeptidase under frozen state conditions. Protease‐catalysed coupling of two acidic amino acids was demonstrated for the first time. The utilization of Glu/Asp‐specific endopeptidase fromBacillus licheniformisin frozen aqueous systems offers new possibilities in enzyme‐catalysed peptide synthesis. Copyright © 2000 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/1099-1387(200008)6:8<366::AID-PSC262>3.0.CO;2-5

出版商:John Wiley&Sons, Ltd.    

年代:2000

数据来源: WILEY

摘要:

AbstractIn order to test the effect of thiopalmitoylation on the encephalitogenic properties of two proteolipid protein (PLP) T‐cell epitopes, we have studied the on‐resinS‐palmitoylation of peptides, synthesized using the Fmoc/tBu strategy. The use of two Cys protecting groups was investigated: thetert‐butylsulfenyl (StBu) and the methoxytrityl (Mmt). Our studies show that the ease of deprotection of the thiol protected with StBu was sequence dependent. The deprotection of Cys(StBu) was difficult in the case of the two peptides PLP(104–117) and PLP(139–151). Neither of the two Cys(StBu) (Cys108and Cys140, respectively) could be deprotected with tributylphosphine. β‐mercaptoethanol was only efficient for the deprotection of Cys(StBu)140at 85°C and at 135°C for Cys108. The two palmitoylated peptides could be obtained in good yield starting from Cys protected with Mmt. Our conclusion is that the Mmt group is the more versatile protecting group of the thiol for use in the on‐resin synthesis of thiopalmitoylated peptides. Copyright © 2000 European Peptide Society and J

ISSN:1075-2617    

DOI:10.1002/1099-1387(200008)6:8<372::AID-PSC264>3.0.CO;2-A

出版商:John Wiley&Sons, Ltd.    

年代:2000

数据来源: WILEY

摘要:

AbstractRecombinant epitopic peptides BP1 and BP2 representing the Bullous pemphigoid autoantigens of BP230 and BP180 bound to the fusion partner glutathione‐S‐transferase (pGEX‐4T‐2, Pharmacia) have been previously shown to increase the efficacy of diagnosis of the disease. Using glutathione‐S‐transferase‐bound monomer peptides, the sensitivity of the immunological reaction exceeded that of the free synthetic epitopes and was further increased with the number of epitopic blocks in the multimer fusion products. This has been explained by the avidity effect of the fusion partner dimer formation and the high ligand affinity due to the tandem repetitions of epitopic sequences. However, a beneficial conformation of the bound epitopic peptides might also contribute to the above phenomenon. Circular dichroism (CD) and Fourier transform infrared (FTIR) absorption spectroscopic studies revealed the importance of glutathione‐S‐transferase to induce and stabilize ordered secondary structures of the epitopic peptides. The free monomer and multimer peptides in aqueous buffer were present as a mixture of unordered and β‐sheet conformation, while binding them to the fusion partner the proportion of ordered secondary structures increased in parallel with the number of antigenic epitopes. The most prominent changes in the conformational state of the monomers in the fusion form were the increase of α‐helical and β‐sheet and the decrease of unordered conformation, while in the case of oligomeric peptides the adoption of a helical conformation was accompanied by the decrease of β‐sheet structure. An outstanding α‐helix content (46%) was detected in the case of the trimeric BP1 in its recombinant fusion form. Copyright © 2000 European Peptide

ISSN:1075-2617    

DOI:10.1002/1099-1387(200008)6:8<378::AID-PSC265>3.0.CO;2-Q

出版商:John Wiley&Sons, Ltd.    

年代:2000

数据来源: WILEY

摘要:

AbstractAn efficient strategy for the synthesis of orexin A, a recently discovered neuropeptide with two intramolecular disulphide bonds, was developed. Four different methods for the synthesis of peptides containing two disulphide bonds were compared and optimized with respect to reaction time, purity of the crude peptide and yield of the purified peptide. A new one‐step cyclization method in solution is presented for fast, easy and high yield synthesis of orexin A, based on iodine oxidation in acetic acid/water andS‐acetamidomethyl (S‐Acm) andS‐trityl (S‐Trt) for side‐chain protection of cysteine. Disulphide formation without selective side‐chain protection leads to the formation of different mono‐ and bicyclic configurations of orexin A. These data stress the requirement of selective cysteine side‐chain protection in the synthesis of orexin A. Copyright © 2000 European Peptide Society and Jo

ISSN:1075-2617    

DOI:10.1002/1099-1387(200008)6:8<387::AID-PSC267>3.0.CO;2-M

出版商:John Wiley&Sons, Ltd.    

年代:2000

数据来源: WILEY

摘要:

AbstractAdditional structure–activity relationship studies on potent cyclic peptide inhibitors of very late antigen‐4 (VLA‐4) are reported. The newN‐ toC‐terminal cyclic hexa‐, hepta‐ and octapeptide inhibitors like cyclo(MeIle/MePhe‐Leu‐Asp‐Val‐X) (X=2–4 amino acids containing hydrophobic and/or basic side chains) were synthesized using solid phase peptide synthesis methods. The peptides were evaluated inin vitrocell adhesion assays and inin vivoinflammation models. Many of the peptides like cyclo(MePhe‐Leu‐Asp‐Val‐d‐Arg‐d‐Arg) (ZD7349) (17), cyclo(MeIle‐Leu‐Asp‐Val‐d‐Arg‐d‐Arg‐d‐Phe) (20), cyclo(MeIle‐Leu‐Asp‐Val‐d‐Arg‐d‐Arg‐MePhe) (21) and cyclo(MePhe‐Leu‐Asp‐Val‐d‐Arg‐d‐Arg‐d‐Ala‐d‐Ala) (23) were potent inhibitors of VLA‐4‐mediated cell adhesion and inhibited ovalbumin‐induced delayed type hypersensitivity (DTH) response in mice. The more potent compounds were highly selective and did not affect U937 cell adhesion to fibronectin (VLA‐5), phorbolmyristate acetate or PMA‐differentiated U937 cell adhesion to intercellular cell adhesion molecule‐1 (ICAM‐1)‐expressing Chinese hamster ovary cells (LFA‐1) and adenosine diphosphate (ADP)‐induced platelet aggregation (GPIIb/IIIa). In contrast to the inhibitors like Ac‐cyclo(d‐Lys‐d‐Ile‐Leu‐Asp‐Val) and cyclo(CH2CO‐Ile‐Leu‐Asp‐Val‐Pip‐CH2CO‐Ile‐Leu‐Asp‐Val‐Pip) described earlier, the new compounds were much more compatible with the depot formulations based on poly(dl‐lactide‐co‐glycolide) polymers. The hexapeptide cyclo(MePhe‐Leu‐Asp‐Val‐d‐Arg‐d‐Arg) (ZD7349) (17) inhibited MOLT‐4 cell adhesion to fibronectin and vascular cell adhesion molecule‐1 (VCAM‐1) with IC50values of 260 and 330 nm, respectively, and did not show any significant effect against other integrins (IC50>300 μm). ZD7349 inhibited ovalbumin‐induced DTH response in mice when administered continuously using a mini‐pump (ED500.01 mg/kg/day) or when given as an s.c. or i.v. bolus injection at a dose of 1–10 mg/kg. ZD7349 was also active in type II collagen‐induced arthritis (CIA) and experimental autoimmune encephalomyelitis (EAE) tests at a dose of 3–10 mg/kg. The peptide was

ISSN:1075-2617    

DOI:10.1002/1099-1387(200008)6:8<398::AID-PSC270>3.0.CO;2-1

出版商:John Wiley&Sons, Ltd.    

年代:2000

数据来源: WILEY

摘要:

AbstractInsulin and C‐peptide were extracted and purified from fox (Vulpes vulpes) pancreas using gel filtration, ion‐exchange chromatography and HPLC. Chromatographic data for the insulin, as well as for its oxidized and carboxymethylated chains proved it to be identical to that of polar fox (Alopex lagopus) and dog. The sequence analysis of a peptide which was assumed to be the corresponding C‐peptide revealed that it comprises 23 amino acid residues and is identical to the C‐peptide fragment isolated from dog pancreas; it differs from polar fox C‐peptide by a single substitution (Asp→Glu). mRNA was isolated from pancreatic tissue and cDNA was obtained by reverse transcription. A polymerase chain reaction was performed using gene‐specific primers to obtain a DNA fragment corresponding to part of fox proinsulin. DNA sequencing revealed 100% identity to dog proinsulin at the protein level, although some amino acids were encoded by different codons. The total sequence of proinsulin was deduced from these results. Copyright © 2000 European Peptide Society and John W

ISSN:1075-2617    

DOI:10.1002/1099-1387(200008)6:8<413::AID-PSC268>3.0.CO;2-Z

出版商:John Wiley&Sons, Ltd.    

年代:2000

数据来源: WILEY