摘要:

AbstractAnoplin, an antimicrobial, helical decapeptide from wasp venom, looses its biological activities by mere deamidation of itsC‐terminus. Secondary structure determination, by circular dichroism spectroscopy in amphipathic environments, and lytic activity in zwitterionic and anionic vesicles showed quite similar results for the amidated and the carboxylated forms of the peptide. The deamidation of theC‐terminus introduced a negative charge at an all‐positive charged peptide, causing a loss of amphipathicity, as indicated by molecular dynamics simulations in TFE/water mixtures and this subtle modification in a peptide's primary structure disturbed the interaction with bilayers and biological membranes. Although being poorly lytic, the amidated form, but not the carboxylated, presented ion channel‐like activity on anionic bilayers with a well‐defined conductance step; at approximately the same concentration it showed antimicrobial activity. The pores remain open attrans‐negative potentials, preferentially conducting cations, and this situation is equivalent to the interaction of the peptide with bacterial membranes that also maintain a high negative potential inside. Copyright © 2007 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.960

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractWe chose the larvae of fleshflySarcophaga bullatato map the peptide and protein immune response. The hemolymph of the third‐instar larvae ofS. bullatawas used for isolation. The larvae were injected with bacterial suspension to induce an antimicrobial response. The hemolymph was separated into crude fractions, which were subdivided by RP‐HPLC, gel electrophoresis, and free‐flow electrophoresis. In several fractions, we determined significant antimicrobial activities against the pathogenic bacteriaEscherichia coli, Staphylococcus aureus,orPseudomonas aeruginosa. Among antimicrobially active compounds we identified dipeptide β‐alanyl‐L‐tyrosine, protein transferrin, and two variants of peptide sapecin. We also partially characterized two novel antimicrobially active polypeptides; odorant‐binding protein 99b, and a peptide which remains unidentified. Copyright © 2007 European Peptide Society and John

ISSN:1075-2617    

DOI:10.1002/psc.967

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractIn this study we describe the first protocols for the synthesis of cystine‐rich peptides in the presence of microwave radiation with Boc‐solid phase peptide synthesis (SPPS). This method is exemplified for macrocyclic peptides known as cyclotides, which comprise ∼30 amino acids and incorporate a cystine knot arrangement of their three disulfide bonds. However, the method is broadly applicable for a wide range of peptides using Boc‐SPPS, especially for SPPS of large peptides via native chemical ligation. Microwave radiation produces peptides in high yield and with high purity, and we were able to reduce the time for the assembly of ∼30 mer peptide chains to an overnight reaction in the automated microwave‐assisted synthesis. Copyright © 2007 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.972

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractTo provide multiple conjugating sites on cyclic peptides for their increasing biomedical applications, a tailed cyclic RGD peptide, c[RGDfE(GGGKK‐NH2)] was designed with c(RGDfE) linked through Glu to a tail consisting of a spacer of three Gly residues and a linker of two Lys residues. The spacer is used to increase the mobility and binding ability of the c(RGDfE) ligand, and the linker is used to proved multiple active sites for conjugating other molecules or biomaterials. We found that the sequence of Glu(Gly)‐OAll leads to glutarimide formation, which disrupts the formation of cyclic RGD peptides. However, our results show that glutarimide formation is sequence dependent and can be inhibited by incorporating an amino acid like Lys(Boc) with steric hindrance from the protecting group. To prevent glutarimide formation, Ser(tBu) was used to replace the glycine in the GGG spacer adjacent to the residue of Glu, and a tailed cyclic RGD peptide, c[RGDfE(SGGKK‐NH2)] was successfully obtained. Copyright © 2007 European Peptide Society and John Wiley&Son

ISSN:1075-2617    

DOI:10.1002/psc.975

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractTwo aspects were studied to elucidate the functional and structural characterization of apidaecin and itsN‐terminal andC‐terminal fragments: (i) Functions of theN‐terminal andC‐terminal fragments of apidaecin were first studied by measuring their antibacterial activity, their ability to enterEscherichia colicells and their effects on the activities of β‐galactosidase and alkaline phosphatase. The results indicate that neither theN‐terminal nor theC‐terminal of apidaecin contains intracellular delivery unit or active segment. (ii) The effect of apidaecin on the ATPase activity of DnaK, and the interactions of apidaecin withE.colilidless DnaK and DnaK D‐E helix were studied. Results showed that apidaecin could interact with theE.colilidless DnaK protein and stimulate its ATPase activity, but not withE.coliDnaK D‐E helix. This indicated that the antimicrobial activity of apidaecin may be shown by stimulating the ATPase activity of DnaK by binding to its conventional substrate‐binding site, to decrease its cellular concentration of DnaK by competing with natural substrates and inhibit the enzymes' activities ofE. colicells. It is the first study to suggest that the apidaecin‐binding site of DnaK is the conventional substrate binging site. Copyright © 2007 European Peptide Society a

ISSN:1075-2617    

DOI:10.1002/psc.976

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractThe subject of these studies was a search for proctolin antagonists among peptides originating from insect species because the proctolin antagonists constantly pose a problem. During these studies we performed the synthesis of the following peptides: a native decapeptide fromManduca sextaMas‐MT‐I and its 11 analogs with shortened sequences at theN‐end as well as a growth suppressor, a pentapeptide isolated fromAntheraea yamamai, Any‐GS and its 10 analogs, modified at position 1 and with a shortened peptide chain.Biological effects were evaluated by the cardiotropic test on the semi‐isolated heart of the insect speciesTenebrio molitor. Mas‐MT‐I and six analogs stimulate the heartbeat frequency, especially [6–10]‐Mas‐MT‐I, whereas the [4–10]‐Mas‐MT‐I analog shows a strong inhibition of the heartbeat frequency, if insect. The Any‐GS and the analogs [Gln1]‐ and [Gly1]‐Any‐GS also show a strong cardioinhibitory effect. Copyright © 2008 European Pe

ISSN:1075-2617    

DOI:10.1002/psc.977

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractCore peptide (CP; GLRILLLKV) is a 9‐amino acid peptide derived from the transmembrane sequence of the T‐cell antigen receptor (TCR) α‐subunit. CP inhibits T‐cell activation bothin vitroandin vivoby disruption of the TCR at the membrane level. To elucidate CP interactions with lipids, surface plasmon resonance (SPR) and circular dichroism (CD) were used to examine CP binding and secondary structure in the presence of either the anionic dimyristoyl‐L‐α‐phosphatidyl‐DL‐glycerol (DMPG), or the zwitterionic dimyristoyl‐L‐α‐phoshatidyl choline (DMPC).Using lipid monolayers and bilayers, SPR experiments demonstrated that irreversible peptide–lipid binding required the hydrophobic interior provided by a membrane bilayer. The importance of electrostatic interactions between CP and phospholipids was highlighted on lipid monolayers as CP bound reversibly to anionic DMPG monolayers, with no detectable binding observed on neutral DMPC monolayers.CD revealed a dose‐dependent conformational change of CP from a dominantly random coil structure to that of β‐structure as the concentration of lipid increased relative to CP. This occurred only in the presence of the anionic DMPG at a lipid : peptide molar ratio of 1.6:1 as no conformational change was observed when the zwitterionic DMPC was tested up to a lipid : peptide ratio of 8.4 : 1. Copyright © 2008 European Peptid

ISSN:1075-2617    

DOI:10.1002/psc.987

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractOne of the main objectives of our current work is the development of new somatostatin analogs that would retain the general characteristics of [Tyr3]octreotate (Tate) while showing potential for clinical application. In this respect, study of their interaction with the sst2is crucial in providing preliminary structure‐activity relationships data. In the present work we report on the synthesis and the preliminary biological evaluation of a total of 15 new structurally modified [Tyr3]octreotate analogs. The binding affinities were determined during competition binding assays in sst2‐positive rat acinar pancreatic AR4‐2J cell membranes using [125I‐Tyr3]octreotide as the radioligand. Copyright © 2008 European Peptide Society and John Wiley&S

ISSN:1075-2617    

DOI:10.1002/psc.989

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractCD and infrared spectroscopic studies were performed on (i) the inhibitory effects of equimolar quantities of LPFFD‐OH and LPYFD‐NH2on the time‐dependent aggregation of amyloid β‐protein (Aβ) (1–42) and (ii) the β‐sheet‐breaker effects of two‐fold molar excess of the pentapeptides on aggregated Aβ(1–42) aged 1 week. The data obtained from the time‐dependent studies demonstrated that LPFFD‐OH did not significantly influence, whereas LPYFD‐NH2exerted some inhibitory effect on the aggregation of Aβ(1–42). When added to a solution of Aβ(1–42) aged 1 week, LPFFD‐OH accelerated, while LPYFD‐NH2delayed, but did not prevent further fibrillogenesis. The difference in the effects of these two pentapeptides on the aggregational profile of Aβ(1–42) is probably due to the difference in their conformational preferences: LPFFD‐OH adopts a β‐turn and extended structures, while LPYFD‐NH2adopts a prevailing β‐turn conformation. Copyright © 200

ISSN:1075-2617    

DOI:10.1002/psc.990

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractKissper is a 39‐residue peptide isolated from kiwi fruit (Actinidia deliciosa). Its primary structure, elucidated by direct protein sequencing, is identical to theN‐terminal region of kiwellin, a recently reported kiwi fruit allergenic protein, suggesting that kissper derives from thein vivoprocessing of kiwellin. The peptide does not show high sequence identity with any other polypeptide of known function. However, it displays a pattern of cysteines similar, but not identical, to those observed in some plant and animal proteins, including toxins involved in defence mechanisms. A number of these proteins are also active on mammalian cells. Functional characterization of kissper showed pH‐dependent and voltage‐gated pore‐forming activity, together with anion selectivity and channeling in model synthetic PLMs, made up of POPC and of DOPS:DOPE:POPC. A 2DNMR analysis indicates that in aqueous solution kissper has only short regions of regular secondary structure, without any evident similarity with other bioactive peptides. Comparative analysis of the structural and functional features suggests that kissper is a member of a new class of pore‐forming peptides with potential effects on human health. Copyright © 2008 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.992

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY