摘要:

AbstractNatural anti‐bacterial peptides cecropin B (CB) and its analogs cecropin B‐1 (CB‐1), cecropin B‐2 (CB‐2) and cecropin B‐3 (CB‐3) were prepared. The different characteristics of these peptides, with amphipathic/hydrophobicα‐helices for CB, amphipathic/amphipathicα‐helices for CB‐1/CB‐2, and hydrophobic/hydrophobicα‐helices for CB‐3, were used to study the morphological changes in the bacterial cell,Klebsiella pneumoniaeand the leukemia cancer cell, HL‐60, by scanning and transmission electron microscopies. The natural and analog peptides have comparable secondary structures as shown by circular dichroism measurements. This indicates that the potency of the peptides on cell membranes is dependent of the helical characteristics rather than the helical strength. The microscopic results show that the morphological changes of the cells treated with CB are distinguishably different from those treated with CB‐1/CB‐2, which are designed to have enhanced anti‐cancer properties by having an extra amphipathicα‐helix. The morphological differences may be due to their different modes of action on the cell membranes resulting in the different potencies with lower lethal concentration and higher concentration of 50% inhibition (IC50) of CB on bacterium and cancer cell, respectively, as compared with CB‐1/CB‐2 (Chenet al.1997. Biochim. Biophys. Acta 1336, 171–179). In contrast, CB‐3 has little effect on either the bacterium or the cancer cell. These results provide microscopic evidence that different killing pathways are involved with the peptides. © 1998 E

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199811)4:7<413::AID-PSC160>3.0.CO;2-W

出版商:John Wiley&Sons, Ltd.    

年代:1998

数据来源: WILEY

摘要:

AbstractVpr, one of the accessory gene products encoded by HIV‐1, is a 96‐residue protein with a number of functions, including targeting of the viral pre‐integration complex to the nucleus and inducing growth arrest of dividing cells. We have characterized by 2D NMR the solution conformations of bioactive synthetic peptide fragments of Vpr encompassing a pair of H(F/S)RIG sequence motifs (residues 71–75 and 78–82 of HIV‐1 Vpr) that cause cell membrane permeabilization and death in yeast and mammalian cells. Due to limited solubility of the peptides in water, their structures were studied in aqueous trifluoroethanol. Peptide Vpr59–86(residues 59–86 of Vpr) formed anα‐helix encompassing residues 60–77, with a kink in the vicinity of residue 62. The first of the repeated sequence motifs (HFRIG) participated in the well‐definedα‐helical domain whereas the second (HSRIG) lay outside the helical domain and formed a reverse turn followed by a less ordered region. On the other hand, peptides Vpr71–82and Vpr71–96, in which the sequence motifs were located at the N‐terminus, were largely unstructured under similar conditions, as judged by their CαH chemical shifts. Thus, the HFRIG and HSRIG motifs adoptα‐helical and turn structures, respectively, when preceded by a helical structure, but are largely unstructured in isolation. The implications of these findings for interpretation of the structure–function relationships of synthetic peptides containing these motifs are discussed. © 1998 European Pe

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199811)4:7<426::AID-PSC161>3.0.CO;2-J

出版商:John Wiley&Sons, Ltd.    

年代:1998

数据来源: WILEY

摘要:

AbstractWe have previously demonstrated that a 23‐amino acid peptide derived from the V3 loop of the surface glycoprotein of the HIV‐1 strain MN is able to bind CD4 and to enhance HIV‐1 infection. Further studies have suggested that the peptide/CD4 interaction induces an increase in both CD4 expression and CD4/gp120 binding affinity. This paper describes the biological and physico‐chemical characterization of three analogues of reduced sequence that have been designed in order to identify the minimum active sequence of this peptide corresponding to the MN‐HIV‐1 principal neutralizing domain. Biological studies indicate that the entire sequence is required for biological activity and that the sequence 1–18 presents an inhibitory activity. CD and FT‐IR absorption data are discussed here in order to identify possible structure‐function correlations. © 1998 European Peptide Society and Jo

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199811)4:7<436::AID-PSC163>3.0.CO;2-C

出版商:John Wiley&Sons, Ltd.    

年代:1998

数据来源: WILEY

摘要:

AbstractWe have studied the effects of extrinsic environmental conditions on the conformation of surfactin, a heptapeptide biosurfactant fromBacillus subtilis, in aqueous solutions. It has been made clear that temperature, pH, Ca2+ions and the synthetic nonionic surfactant hepta‐ethylene glycol (C12E7) affect the conformation of surfactin in aqueous solutions. Theβ‐sheet formation reached a maximum at 40°C both in presence and absence of (C12E7) and the nonionic surfactant enhances theβ‐sheet formation even at 25°C. Ca2+induced the formation of a‐helices and caused this transition at 0.3 mmwith surfactin monomers or at 0.5 mmwith surfactin micelles, but above these transition concentrations of Ca2+β‐sheets were observed. In micellar solution theβ‐sheet structure was stabilized at pH values below 7 or upon addition of Ca2+in concentrations above 0.5 mm. Our results indicated that the bioactive conformation of surfactin is most likely theβ‐sheets when the molecules are assembled in micelles. Theβ‐sheet structure in micelles could be retained by tuning the micelles. Surfactin micelles could be tuned in the bioactive conformation by manipulating pH, temperature, Ca2+or (C12E7) concentrations in surfactin solutions. Our results strongly indicated that Ca2+and other molecules (such as C12E7) may function as directing templates in the assembly and conformation of surfactin in micelles. Thus, we suggest environmental manipulation and template‐aided micellation (TAM) as a new approach for preparing predesigned micelles, microemulsions or micro‐spheres for specific application purposes. © 1998 European Peptide Soci

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199811)4:7<449::AID-PSC164>3.0.CO;2-#

出版商:John Wiley&Sons, Ltd.    

年代:1998

数据来源: WILEY