摘要:

Six Thr1(O‐glyco)‐derivatives of the “phagocytosis stimulating peptide” tuftsin, H‐Thr‐Lys‐Pro‐Arg‐OH and the N‐glycosylated undecapeptide H‐Thr‐Lys‐Pro‐Arg‐Glu‐Gln‐Gln‐Tyr‐Asn(β‐d‐GlcNAc)‐Ser‐Thr‐OH, which correspond to the “tuftsin‐region” at the Fc‐domain of immunoglobulin G (amino acid residues 289–299), were evaluated in comparison with tuftsin and rigin, H‐Gly‐Gln‐Pro‐Arg‐OH, for their capacity to evoke the release of interleukin‐1 and tumor necrosis factor from mouse peritoneal macrophages and from human monocytes. Several glycosylated tuftsin derivatives were found to modulate, in a rather dose

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1991.tb00265.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The insertion of the (S)‐lactyl residue into the cyclodipeptidecyclo(‐Tau‐Pro‐) 3 leads in good yields to the first example of a stable tetrahedral adduct (oxa‐cyclol) 5 containing the sulphonamide junction. Compound 5 does not show a significant tendency towards tautomeric equilibria and possesses an unexpectedsyn‐orientation involving the hydroxyl group and the Pro‐Hα. The crystal structure and molecular conformation of 5 has been determined. Crystals are orthorhombic, s.g. P212121, with a = 6.607, b = 12.297, c = 16.622 Å. The cisoidal conformation around the S‐N bond is very similar to that found in the previously studied linear and cyclic peptides containing a sulphonamide junction. The taurine nitrogen is practically planar whereas the proline nitrogen, bound to the SO2group, is highly pyramidal. In the tricyclic system of 5 the seven‐membered ring adopts a twist‐chair conformation while the pyrrolidine and oxazolidinone rings show an envelope conformation. The crystal packing is characterized by three hydrogen bonds all formed by mean

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1991.tb00266.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The solution conformation of Endothelin‐1, a recently discovered bicyclic, 21 amino acid peptide, has been examined by1H NMR in deuterated dimethylsulphoxide and circular dichroism in aqueous and organic solvents. A total of 158 NOES were detected, which were used as distance constraints in the distance geometry program DISGEO. Two families of structures were obtained, both characterized by a helix‐like region extending from Lys9to Cys15, but with opposite “handedness”. Circular dichroism studies of the peptide in both aqueous and trifluoroethanol solutions show a negative shoulder at 224 nm, characteristic of right‐handed helices. Molecular dynamics and energy minimization yielded a solution structure for this new peptide compatible with all experimental obs

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1991.tb00267.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The analogues [Glu(OBzl)11]SP6–11and [Glu(OBzl)11]SP5–11of the C‐terminal hexapeptide and heptapeptide of Substance P have been synthesized by conventional solution methods. In each analogue the SCH3group of Met11is replaced by the COOCH2C6H5group. Thein vitroactivity of both analogues has been determined on three biological preparations: guinea pig ileum (GPI), rat vas deferens (RVD), and rat portal vein (RPV). The selectivity for the different receptors has been studied by utilizing atropine‐treated guinea pig ileum (GPI + At). The results showed that both analogues are mainly active on GPI through the NK‐1 receptor and that both analogues are equipotent to Su

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1991.tb00268.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Porcine secretin, [Tyr10] secretin, and [Tyr13] secretin were synthesized by solid phase methodology and purified by stepwise gradient elution from a short reversed‐phase column with ethanol and acetic acid as organic modifiers. [Tyr10] secretin and [Tyr13] secretin were iodinated by the chloramine‐T method and non‐, mono‐, and di‐iodinated products separated and isolated by reversed‐phase HPLC. Batch incubation analysis in isolated mouse pancreatic islets revealed that secretin and the [Tyr10] analogue were indistinguishable in their effect on the glucose‐induced insulin release and cAMP accumulation. [Tyr13] secretin in contrast was significantly less potent in its effect on the glucose‐induced

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1991.tb00269.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The structure of Z‐Proψ[CN4]‐Ala‐OBzl has been determined by X‐ray crystallographic techniques. The structure crystallizes in space group P21with cell constants a = 22.176(3) Å, b = 6.141(1)Å, c = 8.275(1) Å, β= 98.31(1), and Z = 2. The structure has been refined to a residual of 0.038 for 2538 independent data. The amide bond between the prolyl and alanyl residues iscis, a result of the presence of the tetrazole ring system, as is the urethane bond linking the benzyloxycarbonyl and the prolyl groups. A comparison of the structures in this study to other structures containingcisamide bonds shows that the tetrazole ring system, when incorporated into peptides, mimics acisamide bond. Changes in the distance between the α‐carbons adjacent to the tetrazole rings in the linear peptide as compared with the bicyclic diketopiperazine required a reassessment of the conformational mimicry with t

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1991.tb00270.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Four cyclic analogs of thymopentin were synthesized and evaluated for biological activity on the human T cell line CEM. Three of these conformationally restricted analogs were biologically active. The one analog which most closely mimicked the conformation predicted from NMR and theoretical energy minimization calculations proved to be inactive. These studies establish that the biologically active conformations of thymopentin differ from the most probable conformation predicted from solution NMR and theoretical energy minimization studies.

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1991.tb00271.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Tripeptides Boc‐X‐Glu‐Val where X is α‐methyl glutamic acid or various cyclic analogues of glutamic acid, such as 1‐amino‐1,3‐dicarboxycyclohexane (cisortrans‐CHGA) or ‐cyclopentane (cisortrans‐CPGA) have been synthesized. Methods for the selective protection, activation, and coupling of such unnatural amino acids are described. The peptides, which are potential competitive inhibitors of the vitamin K‐dependent carboxylation, have been preliminarily tested with the rat liver microsomal carboxylase and found to be effective substrates of the

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1991.tb00272.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

A pseudopeptide analog of the active core of the leucokinin insect neuropeptide family was synthesized and found to retain myotropic activity. No reports of active pseudopeptide analogs of an insect or other invertebrate neuropeptide have previously appeared in the literature. The pseudopeptide (Pheψ[CH2‐NH] Phe‐Ser‐Trp‐Gly‐NH2) contains a reduced‐amide linkage between the twoN‐terminal Phe residues. Unlike its amide‐bond containing counterpart, the activity of the pseudopeptide was not destroyed upon exposure to

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1991.tb00273.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The previously described cyclic, delta opioid receptor‐selective tetrapeptide H‐Tyr‐d‐Cys‐Phe‐d‐Pen‐OH, where Pen, penicillamine, is β,β‐dimethylcysteine, was modified at residues 2 and 4 by varying combinations ofd‐ andl‐Cys andd‐ andl‐Pen, and effects on mu and delta opioid receptor binding affinities and on potency in the mouse vas deferens (MVD) smooth muscle assay were evaluated. A comparison was drawn between consequences of alterations in this series of analogs and those of analogous modifications in the related cyclic pentapeptide series which includes the highly delta receptor‐selective [d‐Pen2,d‐Pen5]enke‐phalin, DPDPE. Unlike effects observed in the cyclic pentapeptide series, the mu receptor binding affinities of the cyclic tetrapeptides are not dramatically influenced by substitution of Pen for Cys at residue 2. Conversely, while binding of the pentapeptides is only slightly affected by alteration of the chirality of the carboxy‐terminal residue, modification of stereochemistry at the carboxy terminus in the tetrapeptides critically alters binding behavior at both mu and delta sites. In contrast with the pentapeptide series, the tetrapeptides appear to be highly dependent upon primary sequence for binding and activity, as only the lead compound binds with high affinity to the delta site. Results suggest that the less flexible cyclic tetrapeptides, lacking the Gly3residue, display more stringent structural requirements for binding and activity than do t

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1991.tb00274.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY