摘要:

AbstractGlucagon‐like peptide‐1 (GLP‐1), which is an endogenous insulinotropic peptide that can stimulate islet cells to secret insulin, is a promising new drug candidate for the treatment of type 2 diabetes. However, due to the very short half‐life of this peptide, the clinical value of GLP‐1 is restricted. A GLP‐1 peptide analog that had been altered by deletion of five amino acids from theC‐terminus (sGLP‐1) was selected and investigatedin vivofor the therapeutic effect on GK rats with type II DM (T2DM). The results revealed that sGLP‐1 exhibited decreased blood glucose‐lowering ability compared to GLP‐1 in the first week, as measured after once‐daily administration. However, after drug administration for 2 weeks, the blood glucose‐lowering effect of sGLP‐1 became superior to that of GLP‐1. sGLP‐1 reduced apoptosis of the old islets, enhanced insulin production, and promoted new islets replication. sGLP‐1 is a shorter but more efficient GLP‐1 analog for type 2 diabetes management. Because sGLP‐1 prolonged the proliferation and recovery of islet cells, the ability to maintain blood glucose (BG) within a normal range was still present 2 weeks after drug withdrawal. These results confirmed the importance of theC‐terminus of GLP‐1 molecule, and further demonstrated that GLP‐1 (7–37) can be truncated till the 32nd amino acid to have a better long‐term BG lowing function. This result may imply for the presence of glucagon family clearance receptorsin vivoand demonstrates that theC‐terminus participates in GLP‐1 clearance. Copyright © 20

ISSN:1075-2617    

DOI:10.1002/psc.997

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractWe demonstrate the use of statistical molecular design (SMD) in the selection of peptide libraries aimed to systematically investigate antigen‐antibody binding spaces. Earlier, we derived two novel antibodies by mutating the complementarity‐determining region of the anti‐p24 (HIV‐1) single chain Fv antibody, CB4‐1 that had lost their affinity for a p24 epitope‐homologous peptide by 8‐ and 60‐fold. The present study was devoted to explore how peptide libraries can be designed under experimental design criteria for effective screening of peptide antigens. Several small peptide–antigen libraries were selected using SMD principles and their activities were evaluated by their binding to SPOT‐synthesized peptide membranes and by fluorescence polarization (FP). The approach was able to reveal the most critical residues required for antigen binding, and finally to increase the binding activity by proper modifications of amino acids in the peptide antigen. A model of the active peptide binding pocket formed by the mutated scFv and the antigen was compatible with the information gained from the experimental data. Our results suggest that SMD approaches can be used to explore peptide antigen features essential for their interactions with antibodies. Copyright © 2008 European Peptide Society and

ISSN:1075-2617    

DOI:10.1002/psc.999

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractThe human hemorphin LVV‐H7 belongs to the class of µ‐opiod receptor‐binding peptides, which also exhibits significant affinity to insulin‐regulated aminopeptidase (IRAP) thereby affecting IRAP inhibition. The inhibitory potency towards IRAP is of pharmaceutical interest for the treatment of Alzheimer's disease. ConsecutiveN‐terminal cleavage of the first two amino acid residues of LVV‐H7 affects a drastic increase of the binding affinity (V‐H7) but ultimately leads to its complete abolition after cleavage of the next amino acid residue (H7). Therefore, we investigated LVV‐H7 truncation by aminopeptidase M (AP‐M) identified as a LVV‐H7 degrading enzyme potentially regulating hemorphin activity towards IRAPin vivo. Using a selective quantitative multi‐component capillary zone electrophoretic method (CZE‐UV), we analyzed the AP‐M‐mediated subsequent proteolysis of the hemorphins LVV‐H7 (L32‐F41), VV‐H7 (V33‐F41), and V‐H7 (V34‐F41)in vitro. Incubations were carried out with synthetic hemorphins applied as single substrates or in combination. Maximum velocities (Vmax), catalytic constants (turnover numbers,kcat), and specific enzyme activities (EA) were calculated. L32cleavage from LVV‐H7 happens more than two‐times faster (kcat: 140 min−1± 9%, EA: 1.0 U/mg ± 9%) than V33cleavage from VV‐H7 (kcat: 61 min−1± 10%, EA: 0.43 U/mg ± 10%) or V32deletion from V‐H7 (kcat: 62 min−1± 8%, EA: 0.46 U/mg ± 8%). In contrast, we showed that H7 (Y35‐F41) was neither degraded by porcine AP‐M nor did it act as an inhibitor for this enzyme. Determined turnover numbers were in the same dimension as those reported for dynorphin degradation. This is the first time that AP‐M‐mediated truncation of natural underivatized LVV‐H7 and its physiological metabolites was analyzed to determine kinetic parameters useful for understanding hemorphin processing and designing hemorphin‐derived drug candid

ISSN:1075-2617    

DOI:10.1002/psc.1002

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractThe human immunodeficiency virus type 1 (HIV‐1) protein U (VpU) is an accessory protein responsible for enhancement of viral particle release and down regulation of the T‐lymphocyte coreceptor CD4. Direct binding between the cytoplasmic domains of CD4 and VpU as well as phosphorylation of serines 53 and 57 in the cytoplasmic domain of VpU plays a central role in CD4 downregulation. We investigated structural consequences of phosphorylation of the two serines using nuclear magnetic resonance spectroscopy. A uniformly15N and13C stable isotope‐labeled 45‐residue peptide comprising the cytoplasmic domain of VpU (VpUcyt) was recombinantly produced inE .coli. The peptide forms two helices (commonly referred to as helix 2 and 3) in the presence of membrane mimicking dodecylphosphocholine (DPC) micelles, which flank a flexible region containing the two phosphorylation sites. Phosphorylation does not cause any drastic structural changes in the secondary structure of VpUcyt. However, anN‐terminal elongation of helix 3 and a slightly reduced helicity at theC‐terminus of helix 2 are observed upon phosphorylation based on characteristic changes of13Cαand13Cβchemical shifts. Phosphorylation also reduces the local mobility of the protein backbone in the loop region containing the phosphorylation sites according to heteronuclear1H15N nuclear Overhauser enhancement (NOE) data. Copyright © 2008 European Peptide Society and John

ISSN:1075-2617    

DOI:10.1002/psc.1004

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractTwenty‐two fragments of β‐actin and β‐actin‐related protein were isolated from the acidic extracts of rat spleen tissue. β‐Actin fragments (75–90), (78–89), and (78–88), 0.01–1 µM, decreased live cell number of L929 murine tumor fibroblasts by 80–90%, with maximal cytotoxic effect of 30–40%. The fragments of (78–90) segment and the fragment of β‐actin‐related protein (69–77) were less active (inhibitory effect up to 55%, cytotoxic–up to 25%). Copyright © 2008 European Pep

ISSN:1075-2617    

DOI:10.1002/psc.1008

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractThe conformations of four BK antagonists, [D‐Arg0, Hyp3, Thi5,D‐Phe7, Acc8]BK (1), Aaa[D‐Arg0, Hyp3, Thi5,D‐Phe7, Acc8]BK (2), [D‐Arg0, Hyp3, Thi5, 8, Apc7]BK (3), and Aaa[D‐Arg0, Hyp3, Thi5, 8, Apc7]BK (4) were studied by using 2D NMR spectroscopy and MD simulations with time‐averaged (TAV) restraints. According to the results of the NMR measurements, the BK antagonists contain 7–30% of minor conformation resulting fromcis/transisomerization of the peptide bonds preceding either Pro or Hyp residues. The major conformation of each peptide possesses all peptide bonds intransconfiguration. Peptides modified with the Apc residue at position 7 (peptides3and4) possess a higher percentage of minor isomer.Peptide1exhibits the strongest vasodepressor potency among the analogs studied and as a single one forms the βII‐turn in the 2–5 fragment, which is believed to be crucial for antagonistic activity. This peptide is also the most compact. The radius of gyration (Rg) amounts to 6.9 Å and is byca1.5 Å lower than that of the remaining analogs. With peptide4, the ST‐turn of type I within the Ser6‐Thi8fragment was found. Copyright © 2008 European Peptide Socie

ISSN:1075-2617    

DOI:10.1002/psc.1009

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractEight cyclic heptapeptides related to the full sequence of deltorphin have been synthesized. The synthesis of linear peptides containing diamino acid residues in positions 2 and 4 was carried out on a 4‐methylbenzhydrylamine resin. Depending on protection procedures, the N‐protected peptide‐resins or N‐protected peptide amides with free amino groups in the side chains were obtained, which were subsequently treated with bis‐(4‐nitrophenyl)carbonate to form a urea unit. Opioid activities of the peptides were determined in the guinea pig ileum (GPI) and mouse vas deferens (MVD) assays. Several compounds showed high δ opioid agonist potency and high selectivity for δ receptors. The results were compared with those obtained earlier for respective 1–4 deltorphin analogs. The conformations of these peptides have been studied using 2D‐NMR in H2O/D2O and molecular dynamics. We observed that the backbone rings had well defined conformations, while the Tyr and Phe side chains and theC‐terminal tail had significant conformational freedom. The bioassay data and conformational parameters of these peptides were compared with those of previously described, corresponding 1–4 deltorphin analogs. This comparison permitted an assessment of the role of theC‐terminal peptide segment in defining the conformation and receptor interaction of theN‐terminal portion and provided insight into the relationship between the putative bioactive conformations and bioactivity. Copyright © 2008 European Peptide Societ

ISSN:1075-2617    

DOI:10.1002/psc.1010

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractA new method for the determination of the cysteine content of synthetic peptides is described. For this purpose the classical amino acid analysis is not suitable, as cysteine may undergo oxidative dimerisation to cystine during the hydrolysis or evaporation. The intact peptide was reacted withN‐ethylmaleimide (NEM) yielding a stableS‐(N‐ethylsuccinimido)‐cysteine derivative, which could be separated by RP‐HPLC and characterised by mass spectrometry. For the quantitative determination less than 0.1 µMpeptide was sufficient. Copyright © 2008 European Peptide Society and John Wile

ISSN:1075-2617    

DOI:10.1002/psc.1012

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractThis article describes a strategy to develop, starting from ade novodesign, bivalent peptides containing two different (α‐helix and β‐hairpin) and independent secondary‐structure elements. The design was based on the use of conformationally restricted peptide libraries. Structural characterization by NMR revealed that the peptides were stable and did not show any long‐range NOE interactions between theN‐terminal β‐hairpin and theC‐terminal α‐helix. These results suggest that the two elements of secondary structure are stable and well folded. Copyright © 2008 European Peptide Society and

ISSN:1075-2617    

DOI:10.1002/psc.1015

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractIn response to wounding or infection, insects produce a battery of antimicrobial peptides (AMPs) and other defense molecules to kill the invading pathogens. To study their structures, functions, and transcriptional regulation, we synthesizedManduca sextamoricin, a 42‐residue peptide (GKIPVKAIKQAGKVIGKGLRAINIAGTTHDVVSFFRPKKKKH, 4539 Da). The compound exhibited potent antimicrobial activities against a broad spectrum of Gram‐positive and Gram‐negative bacteria with a minimum inhibitory concentration of 1.4 µM. The mRNA levels ofM. sextamoricin increased substantially in fat body and hemocytes after the larvae were challenged with bacterial cells. We determined the solution structure of this AMP by two‐dimensional1H1H ‐nuclear magnetic resonance spectroscopy. The tertiary structure is composed of an eight‐turn α‐helix spanning almost the entire peptide. Insights of relationships between the structure and function are also presented. Copyright © 2008 European Peptide Society and Jo

ISSN:1075-2617    

DOI:10.1002/psc.1016

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY