ISSN:0006-3525    

DOI:10.1002/bip.360320402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe fusion of enveloped viruses to target membranes is promoted by certain viral fusion proteins. However, many other proteins and peptides stabilize bilayer membranes and inhibit membrane fusion. We have evaluated some characteristics of the interaction of peptides that are models of segments of measles and influenza fusion proteins with membranes. Our results indicate that these models of the fusogenic domains of viral fusion proteins promote conversion of model membrane bilayers to nonbilayer phases. This is opposite to the effects of peptides and proteins that inhibit viral fusion. A peptide model for the fusion segment of the HA protein of influenza increased membrane leakage as well as promoted the formation of nonbilayer phases upon acidification from pH 7–5. We analyze the gross conformational features of the peptides, and speculate on how these conformational features relate to the structures of the intact proteins and to their role in promoting membrane fusio

ISSN:0006-3525    

DOI:10.1002/bip.360320403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractA new method of dynamic structure refinement of protein x‐ray crystallography, normal mode refinement; is developed. In this method the Debye–Waller factor is expanded in terms of the low‐frequency normal modes and external normal modes, whose amplitudes and couplings are optimized in the process of crystallographic refinement. By this method, internal and external contributions to the atomic fluctuations can be separated. Also, anisotropic atomic fluctuations and their interatomic correlations can be determined experimentally even with a relatively small number of adjustable parameters. The method is applied to the analysis of experimental data of human lysozyme to reveal its dynamic stru

ISSN:0006-3525    

DOI:10.1002/bip.360320404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractNormal mode calculations have been done on 92 disulfide bridges in 25 known protein structures in order to correlate the SS stretch frequency with the CCSS dihedral angle. It is possible to classify the frequencies into four major categories, which provide a more detailed classification scheme than previously proposed from dialkyl disulfide correlations.

ISSN:0006-3525    

DOI:10.1002/bip.360320405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractA general approach is described for measuring homo‐ and heteronuclear spin coupling constants in polypeptides and small proteins. This method uses selective magnetization transfer to generate cross peaks similar to exclusive correlated spectroscopy (E.COSY) and a large direct spin coupling (1J) in one dimension to “pull apart” cross‐peak components by frequencies much larger than the resonance line width. A general description of this method is presented, along with a brief discussion of spin topology and relaxation effects that must be considered in designing multidimensional nmr pulse sequences for measuring vicinal coupling constants. The principles are demonstrated in designs of several two‐dimensional nmr experiments for determining coupling constants in polypeptides and proteins. These include experiments for measuring3J(HN‐Hα),3J(H i−1α‐15Ni),3J(15N‐Hβ), and3J(Hα‐Hβ) coupling constants, which depend on the polypeptide dihedral angles ϕ, ψ and χ1. Multidimensional nmr experiments developed with this approach will allow measurements of many vicinal coupling constants in peptides, proteins, and other molecules. Coupling constants measured in these spectra can be used to determine backbone and side‐chain conformations, to obtain stereospecific resonance assignments of prochiral atoms, and to characterize conformational distributions of dihedral angles. Combined with information obtained from nuclear Overhauser effect measurements, these data will provide more precise determinations of protein solution

ISSN:0006-3525    

DOI:10.1002/bip.360320406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractSmall peptides initiate sexual conjugation in the yeastSaccharomyces cereuisiaeand this phenomenon is an ideal paradigm for studying the mode of action of mammalian peptide hormones,1H‐nmr spectroscopy was used to examine the conformation of linear and cyclic analogues of the α‐factor (WHWLQLKPGQPMY) in aqueous solution. In all cases peptides that exhibit nmr parameters expected for a type II β‐turn have higher biological activities than those that do not appear to assume this conformation. Based on a simple model for the interaction of the pheromone with its receptor, we prepared fragments of the α‐factor. Several of these fragments either antagonize or potentiate the activity of the α‐factor. The latter represent the first example of peptide fragments that synergize the activity of the par

ISSN:0006-3525    

DOI:10.1002/bip.360320407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe conformation of three fragments of uteroglobin in aqueous solution and in the presence of SDS micelles is described. Two of these fragments correspond to helix II and helix III of uteroglobin, the crystal structure of which is made of four helices. The third peptide comprises helices II and III, with the connecting β‐turn. While helix II does not interact strongly with the micelles, helix III adopts a rather clear α‐helix in this system. The elongation of helix III with the addition of helix II at the N‐terminus somewhat stabilizes the ordered structure. It is possible that the β‐turn found in the crystal is also present i

ISSN:0006-3525    

DOI:10.1002/bip.360320408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractPrediction of the structures of long polypeptides and small proteins has been carried out using conformational energy calculations. These calculations can be applied to large proteins if structured regions of their sequences can be identified. Three different approaches to identifying such sequences are presented. First, sequences of five or more contiguous hydrophobic residues tend to nucleate α‐helices. Second, peptide sequences from parent proteins that have the same biological activities as the parent proteins are highly structured. Third, structured synthetic peptide segments from proteins inhibit the folding of the parent proteins by competing with the corresponding segment of the protein chain for associating with complementary regions. Examples of each of these approaches are present

ISSN:0006-3525    

DOI:10.1002/bip.360320409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractA series of CD measurements were carried out on members of peptides in the endothelin and sarafotoxin families. The helical structures taken by these peptides containing the helical motif with the sequences of Cys‐X‐X‐X‐Cys and Cys‐X‐Cys [Y. Kobayashi et al. (1991)Neurochemistry InternationalVol. 18, pp. 525–534] are classified into three groups: a group of structures of ET‐1, ET‐2 and vasoactive intestinal contractor (VIC), a group of sarafotoxin, an

ISSN:0006-3525    

DOI:10.1002/bip.360320410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractEnergy refinement of the structure of a linear peptide, hirudin56–65, bound to thrombin was carried out using a conformational search method in combination with restrained minimization. Five conformations originated from nmr data and distance geometry calculations having a similar global folding pattern but quite different backbone conformations were used as the starting structures. As a result of this approach, a series of low‐energy conformations compatible with a set of upper and lower bounds of interproton distances determined from transferred nuclear Overhauser effects were found. A comparison among the lowest energy conformations of each run showed that the combination of energy refinement plus distance constraints led to a very well‐defined structure for both the backbone and the side chains of the last 7 residues of the polypeptide. Furthermore, the low‐energy conformations generated with this technique contain a segment of 310‐helix involving the last 5 residues at the COOH ter

ISSN:0006-3525    

DOI:10.1002/bip.360320411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY