摘要:

Attempts were undertaken to develop cyclic β‐casomorphin‐5 analogs with improved opioid activity profiles by deletion of the glycine residue in position 5, leading to analogs structurally related to the opioid peptide morphiceptin (H‐Tyr‐Pro‐Phe‐Pro‐NH2). The tetrapeptide sequence Boc‐Tyr(tBu)‐D‐Xaa‐Phe‐Yaa‐OH (Xaa = Lys, Orn, A2bu; Yaa = Pro in L‐ or D‐configuration) was used to study the influence of ring size and chirality on the yield of cyclization between the ω‐amino group of Xaa and theC‐terminal carboxyl group. In all cases the cyclization reaction was performed under identical experimental conditions to allow a direct comparison with regard to yield and homogeneity. The reaction products were purified by crystallization and liquid chromatography, and were characterized by HPLC, TLC, electrospray mass spectrometry and1H‐NMR spectroscopy. In none of the reactions performed with the cyclization precursors containing proline in the L‐configuration could a cyclic monomer be detected, and the cyclodimer (7–9) was the exclusive product in each case. Cyclodimerization was also the favored reaction in the attempted formation of the 11‐membered ring of the cyclic [D‐A2bu2, D‐Pro4]‐morphiceptin analog12, since only traces of the monomer were found. In the case of both the [D‐Lys2, D‐Pro4]‐analog10and the [D‐Orn2, D‐Pro4]‐ analog11, the cyclomonomer/cyclodimer ratio was about 80: 20. The cyclic monomers10and11showed high opioid activity in the μ‐receptor‐representative guinea pig ileum assay (IC50= 2–5 nM) and in the δ‐receptor representative mouse vas deferens assay (IC50= 50–60 nM), whereas the potency of t

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1996.tb00868.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Serum amyloid A (SAA) is an acute‐phase serum protein which exists in the body in a complex with high‐density lipoprotein (HDL3). It is involved in chronic inflammation and neoplastic diseases in an as yet unknown manner. Toward an understanding of the possible physiological role of SAA we initiated a study of its association with blood proinflammatory cells with which it may interact functionallyin vivo. In the following we describe the binding characteristics of recombinant human SAA to human neutrophils (polymorphonuclear leukocytes; PMNLs) and their plasma membranes. Scatchard analysis of rSAA binding and displacement curves revealed Kdin the nanomolar range. The C‐terminal domain of the protein, i.e. amino acid residues 77‐104, which might reside in serum following SAA degradation and amyloid A formation, was found to inhibit efficiently the binding of the whole protein to neutrophils. The interaction of SAA, and of its related peptides while complexed in HDL3, with human PMNs was also studied. The results suggest that SAA may be involved, in an as yet unknown manner, in the neutrophil‐associated inflammatory

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1996.tb00869.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

A new peptide ligand of the small conductance Ca2+activated K+channels has been purified from the venom (obtained by manual rather than electrical stimulation of the scorpionAndroctonus mauretanicus mauretanicus), by following the inhibition of the125I‐apamin binding to its receptor on rat brain synaptosomes. Only one step on a C18reversed‐phase high‐performance liquid chromatography column was necessary to obtain PO1. Its K0.5for the apamin binding site was 100 nM. The amino acid sequence of PO1 is different from those of leiurotoxin and PO5. For the first time the same peptide was also purified from the venoms of two other species of North African scorpions,Androctonus austmlisandButhus occitanus tunetanus. PO1 was chemically synthesized by the solid‐phase technique and fully characterized. A model of PO1 was constructed by amino acid replacement using PO5 nuclear magnetic resonance studies as the starting model. Structure‐activity relationships between these toxins and their receptor are

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1996.tb00870.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Alanine and N‐methylation scans together with molecular modelling were implemented in order to propose a binding conformation of the minimum active fragment of bombesin (BB), Ac‐BB[7‐14], to the gastrin releasing peptide (GRP) and neuromedin B (NMB) receptors. These data are also used to critically evaluate the previously proposed binding conformations such as x‐helix and antiparallel β‐sheets. This shows that the previously reported conformations do not satisfy the experimental data. A new binding conformation of Ac‐BB[7‐14]is proposed consisting of three consecutive y‐turns followed by a bend and finishing with two y‐turns. This low energy conformation (analogous to a fragment of thymidylate synthase, 2TSC) of bombesin stabilized by five internal hydrogen bonds, and with the side chains of residues Trp8and Leu13held on the same side of the peptide, is in agreement with the experimentally observed data. This and the results of molecular modelling may aid in the synthesis of conformationally restricted high affinity bombesin analogues and/or high affinity template‐based GRP or NMB receptor agon

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1996.tb00871.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The previously described kinetic method of the substrate reaction during irreversible inhibition of enzyme activity [Tsou (1988)Adv. Enzymol. Relat. Areas Mol. Biol.61. 381–436] has been used to study the inactivation kinetics of aminoacylase by dithiothreitol (DTT) and 2‐mercaptoethanol (MET). The results show that the inactivation of aminoacylase by DTT or MET is competitive slow‐reversible inhibition. The microscopic rate constants for the inactivation reaction were determined. Removal of these inhibitors by dialysis can lead to complete recovery of enzymatic activity. The present results also show that the presence of equimolar Zn2+to DTT gives complete protection of the enzyme against the inactivation by DTT. Moreover, addition of equimolar amounts of Zn2+to DTT can induce recovery of the enzymatic activity of DTT‐inactivated enzyme. It is known that aminoacylase from pig kidney contains no disulfide bonds. Therefore, it may be suggested that inactivation of aminoacylase by dithiothreitol or 2‐mercaptoethanol is not due to the reduction of disulfide bonds, and is a competitive slow‐reversible

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1996.tb00872.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The solution structure of the peptide antigen from the receptor binding domain ofPseudomonas aeruginosastrain P1 has been determined using two‐dimensional1H NMR techniques. Ensembles of solution conformations for thetransform of this 23‐residue disulfide bridged peptide have been generated using a simulated annealing procedure in conjunction with distance and torsion angle restraints derived from NMR data. Comparison of the NMR‐derived solution structures of the P1 peptide with those previously determined for the 17‐residue PAK, PAO and KB7 strain peptides [Mclnnes, C.,et al.(1993)Biochemistry32, 13432–13440; Campbell, A.P.,et al.(1995)Biochemistry34, 16255–16268] reveals the common structural motif of a β‐turn, which may be the necessary structural requirement for recognition of a common cell surface receptor and a common cross‐reactive antibody to which all four strains bind. The importance of this conserved β‐turn in the PAK, PAO, KB7 and P1 peptides is discussed with regard to the design of a synthetic peptide vaccine effective against multiple strains ofPseudomonas a

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1996.tb00873.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The synthesis and stability of allyloxycarbonyl (Aloe) indole‐protected Trp derivatives and their application in solid‐phase peptide synthesis are reported. The study shows that the Aloe protection on the indole moiety is suitable for orthogonal protection in the Fmoc/tBu strategy if the Fmoc group is cleaved with DBU. Several tryptophan‐containing peptides have been synthesized including dynorphin A‐(1‐13), which has been intensively studied with respect to side reactions during the final TFA cleavage procedure. The results demonstrate the protective function of the Aloe group on the Trp during final deprotection. Furthermore, it could be demonstrated that Trp(Aloe)‐containing peptides can be isolated and that the Aloe group can then be removed in a second step. The synthesis of phosphorylated delta sleep inducing peptide (P‐DSIP) using the global phosphorylation approach provides another example in which Trp indole protection by Aloe prevents the formation of oxidative

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1996.tb00874.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Among peptide secondary structures β‐sheet domains have been much less intensively studied than α‐helical conformations, mainly because of the lack of well characterized model peptides. In the present paper the secondary structure of a water‐solublede novopeptide consisting of 26 amino acids (DPKGDPKGVTVTVTVTVTGKGDPKPD‐NH2) and the corresponding double D‐amino acid replacement set have been studied by circular dichroism and Fourier‐transform infrared spectroscopy. The model peptide was found to be unstructured in aqueous solution at peptide concentrations<10−3mol/L but to adopt a predominantly β‐sheet structure in the presence of 15 mM sodium dodecyl sulfate or at apolar/water interfaces. Although the peptide is composed of amino acids with low helical propensity, it formed a single‐stranded helical structure in aqueous trifluoroethanol. The D‐amino acid replacement set was synthesized in order to study the conformational stability of the model peptide selectively in distinct regions. The data show that both the α‐helix present in 50% trifluoroethanol as well as the β‐sheet domain formed in the presence of sodium dodecyl sulfate or at apolar/water interfaces, are located in the region between Val9and Thr18. Pairwise substitution of adjacent amino acids by their corresponding D‐amino acids provides a pronounced β‐sheet disturbance. These findings demonstrate that double D‐amino acid replacements may be used to

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1996.tb00875.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The conformations of two backbone‐cyclized substancePanalogs were derived from homo‐ and heteronuclear NMR measurements and molecular dynamics simulations carried out in DMSO. The analogs contain subtle variations in the ring chemistry and are compared with biologically active analogs previously examined. The correlation between conformation and activity is used to gain insight into the conformational requirements from the pharmacoph

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1996.tb00876.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY