摘要:

AbstractIn an attempt to develop non‐ATP‐competitive inhibitors of the autophosphorylation of IR, the effects of the synthetic peptides, Ac‐DIY1158ET‐NH2and Ac‐DY1162Y1163RK‐NH2, on the phosphorylation of IR were studiedin vitro. The peptides were derived from the amino‐acid sequence in the activation loop of IR. They inhibited the autophosphorylation of IR to 20.5 and 40.7%, respectively, at 4000 µM. The Asp/Asn‐ and Glu/Gln‐substituted peptides, Ac‐NIYQT‐NH2and Ac‐NYYRK‐NH2, more potently inhibited the autophosphorylation than did the corresponding parent peptides. The inhibitory potencies of the substituted peptides were decreased with increasing concentrations of ATP, indicating that these peptides employ an ATP‐competitive mechanism in inhibiting the autophosphorylation of IR. In contrast, those of the parent peptides were not affected. Mass spectrometry showed that the parent peptides were phosphorylated by IR, suggesting that they interact with the catalytic loop. Moreover, docking simulations predicted that the substituted peptides would interact with the ATP‐binding region of IR, whereas their parent peptides would interact with the catalytic loop of IR. Thus, Ac‐DIYET‐NH2and Ac‐DYYRK‐NH2are expected to be non‐ATP‐competitive inhibitors. These peptides could contribute to the development of a drug employing a novel mechanism. Copyright © 2009 Europe

ISSN:1075-2617    

DOI:10.1002/psc.1114

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractEndomorphin 1 (EM1), an endogenous µ‐opioid receptor agonist, acts as a free radical scavengerin vitroand an antioxidantin vivo. The modification of EM1 by ROS and the properties of the OM attracted our attention.In vitroassays were performed via RP‐HPLC, spectrophotometric measurements, EPR and amino acid analysis, Schmorl's reaction to define the formation of melanin‐like compounds transformed from EM1, collectively named EM1–melanin and by solubility assay, radioligand‐binding assay, NADH oxidation, superoxide anion scavenging assay to study some physical and chemical properties of EM1–melanin. Possible pathways of the formation of EM1–melanin were proposed. Copyright © 2009 European Peptide Society and John

ISSN:1075-2617    

DOI:10.1002/psc.1116

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractThe cell‐penetrating peptide Tat (48–60) (GRKKRRQRRRPPQ) derived from HIV‐1 Tat protein showed potent antibacterial activity (MIC: 2–8 µM). To investigate the effect of dimerization of Tat (48–60) analog, [Tat(W): GRKKRRQRRRPWQ‐NH2], on antimicrobial activity and mechanism of bactericidal action, its dimeric peptides, di‐Tat(W)‐C and di‐Tat(W)‐K, were synthesized by a disulfide bond linkage and lysine linkage of monomeric Tat(W), respectively. From the viewpoint of a weight basis and the monomer concentration, these dimeric peptides displayed almost similar antimicrobial activity against six bacterial strains tested but acted more rapidly againstStaphylococcus aureuson kinetics of bactericidal activity, compared with monomeric Tat(W). Unlike monomeric Tat(W), these dimeric peptides significantly depolarized the cytoplasmic membrane of intactS. aureuscells at MIC and induced dye leakage from bacterial‐membrane‐mimicking egg yolkL‐α‐phosphatidylethanolamine/egg yolkL‐α‐phosphatidyl‐DL‐glycerol (7:3, w/w) vesicles. Furthermore, these dimeric peptides were less effective to translocate across lipid bilayers than monomeric Tat(W). These results indicated that the dimerization of Tat analog induces a partial change in the mode of its bactericidal action from intracellular target mechanism to membrane‐targeting mechanism. Collectively, our designed dimeric Tat peptides with high antimicrobial activity and rapid bactericidal activity appear to be excellent candidates for future development as novel antimicrobial agents. Copyright © 2009 European

ISSN:1075-2617    

DOI:10.1002/psc.1120

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractThe temperature dependence of the partition of a neuropeptide, substance P (SP), in isotropic (q= 0.5) bicelles was investigated by using pulsed field gradient NMR diffusion technique. The partition coefficient decreases as the temperature is increased from 295 to 325 K, indicating a favorable (negative) enthalpy change upon partitioning of the peptide. Thermodynamic analysis of the data shows that the partitioning of SP at 300 K is driven by the enthalpic term (ΔH) with the value of − 4.03 kcal mol−1, while it is opposed by the entropic term (−TΔS) by approximately 1.28 kcal mol−1with a small negative change in heat capacity (ΔCp). The enthalpy‐driven process for the partition of SP in bicelles is the same as in dodecylphosphocholine (DPC) micelles, however, the negative entropy change in bicelles of flat bilayer surface is in sharp contrast with the positive entropy change in DPC micelles of highly curved surface, indicating that the curvature of the membrane surface might play a significant role in the partitioning of peptides. Copyright © 2009 European Peptide Society and John Wi

ISSN:1075-2617    

DOI:10.1002/psc.1121

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractThe rational design of peptide and protein helices is not only of practical importance for protein engineering but also is a useful approach in attempts to improve our understanding of protein folding. Recent modifications of theoretical models of helix‐coil transitions allow accurate predictions of the helix stability of monomeric peptides in water and provide new possibilities for protein design. We report here a new method for the design of α‐helices in peptides and proteins using AGADIR, the statistical mechanical theory for helix‐coil transitions in monomeric peptides and the tunneling algorithm of global optimization of multidimensional functions for optimization of amino acid sequences. CD measurements of helical content of peptides with optimized sequences indicate that the helical potential of protein amino acids is high enough to allow formation of stable α‐helices in peptides as short as of 10 residues in length. The results show the maximum achievable helix content (HC) of short peptides with fully optimized sequences at 5 °C is expected to be ∼70–75%. Under certain conditions the method can be a powerful practical tool for protein engineering. Unlike traditional approaches that are often used to increase protein stability by adding a few favorable interactions to the protein structure, this method deals with all possible sequences of protein helices and selects the best one from them. Copyright © 2009 European Peptide Society and John

ISSN:1075-2617    

DOI:10.1002/psc.1122

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractThe synthesis of theC‐terminal pentapeptide of culicinins has been achieved using [4 + 1] protocol and reduction‐coupling strategy. Copyright © 2009 European Peptide Society and John Wiley&Sons,

ISSN:1075-2617    

DOI:10.1002/psc.1124

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractSignificant advances have been achieved in the fields of peptide/protein synthesis, permitting the preparation of large, complex molecules. Shortcomings, however, continue to exist in the area of peptide purification. This paper details some studies we undertook to develop a new strategy for peptide purification based on a reactivity of α‐ketoacyl groups in peptides. The α‐ketoacyl peptide was generated fromNε‐acyl‐lysyl‐peptide in the solid phase via a transamination reaction using glyoxylic acid and nickel(II) ion. Cleavage of the α‐ketoacyl group witho‐phenylenediamine gave the target peptide in an acceptable yield and purity. We first carried out a careful step‐by‐step optimization of the purification conditions using a model peptide. The strategy was then used in the purification of a transmembrane peptide that could not be effectively purified using a conventional RP‐HPLC system due to the strong hydrophobicity of the peptide and its high tendency to aggregate. Copyright © 2009 European Peptide Society

ISSN:1075-2617    

DOI:10.1002/psc.1127

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractNatural resistance associated macrophage protein 1 (Nramp1), an integral membrane protein with 12 predicted transmembrane domains (TMs), is a divalent cation transporter associated with infectious and autoimmune diseases. A naturally occurring mutation G169D within TM4 of Nramp1 leads to the loss of function, suggesting potential importance of TM4 for the biological function of the protein. In this study, we determine the three‐dimensional structure and topology of a synthetic peptide, del(T178), corresponding to Nramp1(164‐191) (basically consisting of the putative TM4 of Nramp1) with Thr178 deletion in TFE and SDS micelles using NMR and CD spectroscopic techniques, and compare the results with those of the wildtype peptide. Similarly to the wildtype peptide, the del(T178) peptide still forms an amphiphilic‐like α‐helical structure in both membrane mimics and is embedded in SDS micelles. Differently, whereas the wild‐type peptide forms a helix bundle with the hydrophilic side facing the interior of the bundle, the del(T178) peptide exists as a monomer in the membrane mimics and the hydrophilic side of the helix is located near the interface of SDS micelles. Moreover, a strongly cooperative protonation occurs between intramolecular Asp residues for the del(T178) peptide in SDS micelles, while the cooperative proton binding between intermolecular Asp residues was observed for the wildtype peptide. The difference in the results of the two peptides suggests that the deletion of Thr178 impairs intermolecular interaction of the peptide. Copyright © 2009 European Peptide Society and John Wile

ISSN:1075-2617    

DOI:10.1002/psc.1128

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractTuberculosis (TB) is a bacterial infectious disease caused byMycobacterium tuberculosis, a slow‐growing, powerful human pathogen which can survive in the host macrophages. In the chemotherapy of such intracellular pathogens it is necessary to achieve relatively high level of the drug in blood to attain therapeutically effective concentration in infected cells, which presumably has several serious side effects on healthy tissues. The elimination ofM. tuberculosisfrom infected phagocytes could be more efficient with target cell‐directed delivery of antituberculars. A particularly promising approach is to conjugate a drug moiety to a peptide based carrier. The conjugates are chemically constructed to target release by hydrolysis (enzymatic and/or chemical) to liberate the active compound. Here we report the synthesis, characterisation and antimycobacterial evaluation of isoniazid (INH) peptide conjugates. As carrier moiety T‐cell epitope of immundominant 16‐kDa protein ofM. tuberculosisand tuftsin‐derived peptides were used. To conjugate INH two synthetic methods were developed, where INH was coupled directly to the peptides or through a heterobifunctional reagent. We found that all of the INH conjugates were effective againstM. tuberculosisand the minimal inhibitory concentration (MIC) values were comparable to the free INH moiety. Copyright © 2009 European Peptide Society and John Wiley

ISSN:1075-2617    

DOI:10.1002/psc.1129

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY