摘要:

AbstractMicrowave energy represents an efficient manner to accelerate both the deprotection and coupling reactions in 9‐fluorenylmethyloxycarbonyl (Fmoc) solid phase peptide synthesis (SPPS). Typical SPPS side reactions including racemization and aspartimide formation can occur with microwave energy but can easily be controlled by routine use of optimized methods. Cysteine, histidine, and aspartic acid were susceptible to racemization during microwave SPPS of a model 20mer peptide containing all 20 natural amino acids. Lowering the microwave coupling temperature from 80 °C to 50 °C limited racemization of histidine and cysteine. Additionally, coupling of both histidine and cysteine can be performed conventionally while the rest of the peptide is synthesized using microwave without any deleterious effect, as racemization during the coupling reaction was limited to the activated ester state of the amino acids up to 80 °C. Use of the hindered amine, collidine, in the coupling reaction also minimized formation ofD‐cysteine. Aspartimide formation and subsequent racemization of aspartic acid was reduced by the addition of HOBt to the deprotection solution and/or use of piperazine in place of piperidine. Copyright © 2006 European Peptide Society and John Wiley&So

ISSN:1075-2617    

DOI:10.1002/psc.804

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY

摘要:

AbstractOur previous investigation indicated that insulin can be nitrated by peroxynitritein vitro. In this study, the preferential nitration site of the four tyrosine residues in insulin molecule was confirmed. Mononitrated and dinitrated insulins were purified by RP‐HPLC. Following reduction of insulin disulfide bridges, Native‐PAGE indicated that A‐chain was preferentially nitrated. Combination of enzymatic digestion of mononitrated insulin with endoproteinase Glu‐C, mass spectrometry confirmed that Tyr‐A14 was the preferential nitration site when insulin was treated with peroxynitrite. Tyr‐A19, maybe, was the next preferential nitration site. According to the crystal structure, Tyr‐B26 between the two tyrosine residues in insulin B‐chain was likely easier to be nitrated by peroxynitrite. Copyright © 2006 European Peptide Society and John

ISSN:1075-2617    

DOI:10.1002/psc.805

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY

摘要:

AbstractA 23‐amino acid, bifunctional, integrin‐targeted synthetic peptide was evaluated forex vivogene delivery to rabbit bone marrow stromal cells (BMSCs). The peptide (K)16GRGDSPC consists of an amino terminal domain of 16 lysines for electrostatic binding of DNA, and a 7‐amino acid integrin‐binding domain at the carboxyl terminal. PcDNA3‐EGFP plasmids were transfected into BMSCs by (K)16GRGDSPC and the positive cells gave out a bright green fluorescence. High levels of gene delivery of pcDNA3‐TGF‐β1 plasmids were obtained with 2 to 4 µg/ml DNA concentration, with (K)16GRGDSPC at an optimal peptide: DNA w/w ratio of 3:1, with a required exposure time of more than 4 h but shorter than 24 h for BMSC exposure to the peptide/DNA complexes with completely absent serum in the initial stage; with 100 µMchloroquine and at least 8 h exposure for BMSC exposure to chloroquine; with a fusogenic peptide at an optimal (K)16GRGDSPC/DNA/fusogenic peptide w/w ratio of 3:1:5; and with Lipofectamine 2000 at an optimal (K)16GRGDSPC/DNA/Lipofectamine 2000 w/w ratio of 3:1:2 at a constant DNA concentration of 2 µg/ml. Chloroquine, the fusogenic peptide and Lipofectamine 2000 all significantly promoted gene delivery, but chloroquine was more effective than the fusogenic peptide and had obvious synergistic effects with Lipofectamine 2000. Under optimal conditions, TGF‐β1 gene was transfected into BMSCs without observable toxicity, and the stable expression was examined by RT‐PCR and Western blot analysis. The stable transgenic cells showed obvious bands. This novel synthetic peptide, providing a new way for the use of polylysine and RGD motif in DNA vector system, is potentially well suited toex vivogene delivery to BMSCs for experimental and clinical applications in the field of bone tissue engineering. Copyright © 2006 European Peptide Society a

ISSN:1075-2617    

DOI:10.1002/psc.826

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY

摘要:

AbstractHigh affinity peptide ligands for the bradykinin (BK) B2subtype receptor have been shown to adopt a β‐turn conformation of theC‐terminal tetrapeptide (H‐Arg1‐Pro2‐Pro3‐Gly4‐Phe5‐Ser6‐Pro7‐Phe8‐Arg9‐OH). We investigated the replacement of the Pro7‐Phe8dipeptide moiety in BK or theD‐Tic7‐Oic8subunit in HOE140 (H‐D‐Arg0‐Arg1‐Pro2‐Hyp3‐Gly4‐Thi5‐Ser6‐D‐Tic7‐Oic8‐Arg9‐OH) by 4‐amino‐1,2,4,5‐tetrahydro‐2‐benzazepin‐3‐one templates (Aba). Binding studies to the human B2receptor showed a correlation between the affinities of the BK analogs and the propensity of the templates to adopt a β‐turn conformation. TheL‐spiro‐Aba‐Gly containing HOE140 analog BK10 has the best affinity, which correlates with the known turn‐inducing property of this template. All the compounds did not modify basal inositolphosphate (IP) output in B2‐expressing CHO cells up to 10 µMconcentration. The antagonist properties were confirmed by the guinea pig ileum smooth muscle contractility assay. The new amino‐benzazepinone (Aba) substituted BK analogs were found to be surmou

ISSN:1075-2617    

DOI:10.1002/psc.827

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY

摘要:

AbstractPlantaricin‐149 is a bacteriocin produced byLactobacillus plantarumNRIC 149 (a LAB isolated from pineapple), which consists of a peptidic chain made up of 22 amino acid residues [Katoet al.J. Ferment. Bioeng.1994;77: 277–282]. In this work, a syntheticC‐terminal amidated peptide analog denoted Pln149a was prepared by SPPS‐Fmoc chemistry and the antagonistic activity against gram‐positive and gram‐negative bacteria was tested. The secondary structure was studied by circular dichroism (CD) and the vicinity of the tyrosine residue by fluorescence spectroscopy under different conditions. We report the results of the interaction of Pln149a with reverse micelles prepared from the amphiphilic AOT in cyclohexane.Synthetic plantaricin was active against one strain ofStaphylococcus aureusand four strains ofListeriagenus at pH 5.5 and 7.4 and, like its natural variant, inhibitedL. plantarumATCC 8014.The data derived from spectroscopic measurements in presence of AOT reverse micelles suggest that the secondary structure of the peptide upon interaction is an α‐helix. In this membrane model, the hydrophobic side of the α‐helix is inserted into the micelles, leaving the lysines exposed to the solvent and interacting with the polar moieties of AOT. The fluorescence data point out that theN‐terminal tyrosine residue is close to the micellar interface. Copyright © 2007 European Peptide Society and

ISSN:1075-2617    

DOI:10.1002/psc.828

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY

摘要:

AbstractSyntheses of the [Lys7]‐ and [Hyp6,Lys7]‐dermorphin analogues in which either Tyr5or Hyp6areO‐glucosylated are described. For comparison, the carbohydrate‐free peptides have also been prepared. Structural investigations by FT‐IR and CD measurements were carried out on the synthetic analogues and some preliminary pharmacological experiments were also performed.The biological potency of the glucosylated analogues was compared with that of the µ‐opioid receptor agonist dermorphin in GPI preparations. Glucosylation of either Tyr5or Hyp6reduces the potency of both [Lys7]‐dermorphin and [Hyp6,Lys7]‐dermorphin. The effect induced by the Tyr5glucosylation is quite strong and the potency of both peptides is reduced by about 150 times. A similar but less dramatic effect is induced by the glucosylation of the Hyp6residue, and the potency of the parent peptide is reduced by about 15 times. The presence of acetyl groups on the sugar hydroxyl functions further reduces the agonistic potency of the glucosylated analogues. The analgesic potency of [Hyp6,Lys7]‐, [Hyp(βGlc)6,Lys7]‐ and [Tyr(βGlc)5,Lys7]‐dermorphin were also testedin vivoby the tail‐flick test. The glucosylated hydroxyproline‐containing analogue is 8–10 times less active than the parent peptide, but its analgesic effect lasts significantly longer. Copyright © 2006 European Peptide S

ISSN:1075-2617    

DOI:10.1002/psc.829

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY

摘要:

AbstractThe crystal‐state conformations of the hexapeptide amide Pht‐(Aib)6‐NH‐C(CH3)2‐O‐OtBu (7), the hexapeptide Ac‐L‐aIle‐(Aib)5‐OtBu (6), the pentapeptide Z‐(Aib)3‐L‐Glu(OtBu)‐Aib‐O‐(CH2)2‐(1)Nap (5), the tetrapeptides Z‐(Aib)2‐L‐His(Nτ‐Trt)‐Aib‐OMe (4 I) and Z‐(Aib)2‐L‐Nva‐Aib‐OtBu (4 II), the tripeptide Pyr‐(Aib)3‐OtBu (3 I), the dipeptide amides Pyr‐(Aib)2‐(4)NH‐TEMPO (3 II) and Piv‐(Aib)2‐NH‐C(CH3)2‐O‐OtBu (3 III), and the dipeptides Pht‐Aib‐βAc6c‐OtBu (2 I), Pht‐Aib‐NH‐C(CH3)2‐O‐OtBu (2 II) and Boc‐gGly‐mAib‐OH (2 III) have been determined by X‐ray diffraction analyses. All peptides investigated are characterized by one or more turn/helix forming Aib residues. Except the three short dipeptides, all are folded into CO···HN intramolecularly H‐bonded 310‐helices, or into various types of β‐turns. In the structure of 6, two independent molecules of opposite screw sense were observed in the asymmet

ISSN:1075-2617    

DOI:10.1002/psc.833

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY

摘要:

AbstractPrevious studies demonstrated that the presence of a bulky acyl substituent at theN‐terminus of B2antagonists significantly influenced the interaction of the peptide with B2receptors, thus increasing potency in the blood pressure test. Reported results also suggested that even minor changes in the structure of analogues might be of importance in designing more potent B2antagonists. On the other hand, it was learned that the effects of acylation might vary substantially with the chemical character of the acyl group. It seemed that either the positive or the negative charge on theN‐terminal acyl group influenced the activity of the analogues because a suppressed antagonistic potency due to these modifications was observed.Bearing all these findings in mind, it was decided to check howN‐terminal acylation would affect the pharmacological activity of bradykinin. Of the many acylating agents tested previously on B2antagonists, it was decided to use acridin‐9‐ylacetic acid (Ana) and anthracen‐9‐ylacetic acid (Ata). The potencies of the analogues were assessed by their ability to inhibit vasodepressor response of exogenous BK in conscious rats and by their ability to inhibit the contractions of isolated rat uterus evoked by BK. Copyright © 2006 European Peptide Society and John W

ISSN:1075-2617    

DOI:10.1002/psc.830

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY