摘要:

AbstractThrough the joint use of CD, Fourier transform ir (FTIR), and attenuated total reflectance FTIR we have found that synthetic polypeptide models of thePlasmodium falciparumcircumsporozoite (CS) protein repeat domain bind calcium ions in helicogenic environments. Ca2+‐(NANP)ncomplexes (n⩾ 20) interact vectorially with model phospholipid membranes orienting their polypeptide axes preferentially along those of the lipid acyl chains. It is proposed that theP. falciparumCS protein central region, rather than acting as a molecular lure helping the parasite to evade host immune control, plays, as a specific Ca2+macroligand, a critical functional role during attachment, invasion, and development of the malaria parasite in the hepatic c

ISSN:0006-3525    

DOI:10.1002/bip.360310602

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

年代:1991

数据来源: WILEY

摘要:

AbstractHybrids of the double‐chainbis‐cystinyl fragment 225‐232/225′‐232′ of human immunoglobulin G1 (IgG1) with the human little‐gastrin sequence 2‐17 were found to induce in animals a strong antigastrin humoral immune response with antibody titers comparable to those raised with conventional gastrin/carrier‐protein conjugates. The observed gastrin receptor‐like specificity of the polyclonal antibodies led to the assumption that the gastrin component of the hybrids is still capable of folding into its preferred bioactive structure and thus to express a similar conformational epitope in the dynamic process of recognition by the B‐cell receptors. CD measurements on these hybrid compounds in aqueous and aqueous organic media confirmed the free conformational space for the antigenic gastrin moiety, which is essentially randomly coiled in aqueous solution but retains its ability to fold into the gastrin‐specific ordered structure in aqueous organic media as used to mimic the water‐limited environment of peptides while interacting with target cells at receptor level. The absence of reciprocal conformational restriction in such hybrid molecules suggests that a compact, rigid heterodetic cyclic structure as the hinge peptide is well suited for the multiple attachment of antigenic sequences in view of the preparation of f

ISSN:0006-3525    

DOI:10.1002/bip.360310603

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe proton nmr spectra of bacitracin A in H2O and DMSO‐d6have been assigned and the conformational behavior of the peptide in the two solvents has been compared. Although bacitracin A shows a conformational equilibrium between at least two conformations differing in the relative position of the cyclic and linear domains of the molecule, the spectra in water can be interpreted in terms of a preferred conformation in which the linear part is folded over the cyclic moiety and a turn is present around Ile8‐DP

ISSN:0006-3525    

DOI:10.1002/bip.360310604

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

年代:1991

数据来源: WILEY

摘要:

AbstractC‐terminal analogues of neuropeptide Y (NPY) of small molecular size have been synthesized. The influence of chain length, single or multiple amino acid substitution, and segment substitutions on receptor binding, pre‐ and postsynaptic biological activity, and conformational properties have been investigated. Receptor binding and in vivo assays revealed biological activity for NPY Ac‐25‐36 that increased with increasing α‐helicity. In attempts to stabilize the α‐helical content, three independent types of modified NPY Ac‐25‐36 analogues were synthesized. Strong agonistic activities could be detected in a series of discontinuous analogues, which are constructs of N‐terminal parts linked via different spacer molecules to C‐terminal segments. One of the most active molecules was NPY 1‐4‐Aca‐25‐36 (Aca, ε‐aminocaproic acid). For the first time conformational properties of a series of small NPY analogues have been investigated by CD, and correlated with biological activity and receptor binding. A C‐terminal dodecapeptide segment of NPY with an amount of 50% substitution to the native C‐terminal sequence of NPY was found to

ISSN:0006-3525    

DOI:10.1002/bip.360310605

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

年代:1991

数据来源: WILEY

摘要:

AbstractSeveral new proton‐detected heteronuclear two‐dimensional (2D) nmr techniques are presented that exhibit the features ofselectionandeditingof multiplicity. The theoretical basis of the new features is briefly discussed and the application of the 2D techniques to a thioanalogon of Cyclosporin A [Thio‐(1)‐cyclosporin A] is shown. In addition, an extension of the experiments to three‐dimensional (3D) techniques is demonstrated and the application of two 3D techniques to Thio‐(1)‐cyclosporin A with13C in natural abundance is presented. The new techniques can help simplify heteronuclear shift correlations and increase the resolution in the car

ISSN:0006-3525    

DOI:10.1002/bip.360310606

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

年代:1991

数据来源: WILEY

摘要:

AbstractMinimal sequences of rubella E1 glycoprotein epitopes were previously identified as the tripeptide250PER252for the EP2epitope, the tetrapeptide260ADDP263for the EP3epitope, and the tripeptide273EVW275plus the octapeptide278PVIGSQAR285for the EP1epitope.In order to establish for each epitope the shortest sequence that was able to give the maximum binding with human antirubella immunoglobulins, synthetic peptides with increasing number of residues flanking these essential parts of rubella E1 glycoprotein epitopes were synthesized and examined for their antigenic activity.Usually higher activity was observed with progressively longer homologues, whereas the additions of Pro‐271, Pro‐278 to272GEVWVT277peptide, and additions of Ala‐248 to249TPERP253and249TPERPR254, led to an abrupt decrease in binding. Taken together, our results indicated that the antigenic activity of the whole antigen could be dissected and reproduced using synthetic peptides of appropriate structure for each ep

ISSN:0006-3525    

DOI:10.1002/bip.360310607

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe conformational preference of Cα,α‐diphenylglycinc (Døg) and Cα,α‐dibenzylglycine (Dbz) residues was assessed in selected derivatives and small peptides by conformational energy computations, ir absorption,1H‐nmr, and x‐ray diffraction. Conformational energy computations on the two monopeptides strongly support the view that these Cα,α‐symmetrically disubstituted glycines are conformationally restricted and that their minimum energy conformation falls in the fully extended (C5) region. The results of the theoretical analyses appear to be in agreement with the solution and crystal‐state structural propensities of three derivatives and seven

ISSN:0006-3525    

DOI:10.1002/bip.360310608

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe conformational properties of spantide [(D‐Arg1,D‐Trp7,9, Leu11)substance P] have been studied by fluorescence, CD, and nmr techniques. The fluorescence, CD, and nmr parameters in different solvents and in a micellar environment (SDS) are compared with the data collected for bombesin. A preliminary investigation on [D‐Pro2] spantide is also rep

ISSN:0006-3525    

DOI:10.1002/bip.360310609

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe conformation of the heptacosapeptide hormone, gastrin releasing peptide, has been studied in buffer and in the presence of lipids, using static and dynamic fluorescence and CD. The results obtained show that, in buffer, the hormone exists in a collection of flexible, random coil type conformers, characterized by a β‐turn between residues 14‐19. On the other hand, organic solvents can induce some degree of ordered secondary structure in the peptide chain.The marked changes, observed in CD and fluorescence spectra upon addition of lysolecitin micelles and dimyristoylphosphatidylserine vesicles, clearly show that the peptide interacts with lipids, assuming a lipid specific configuration. Interestingly, no significative spectroscopic changes are produced by exposure to dimyristoylphosphatidylcholine vesicles both in the gel and liquid‐chrystalline phases, suggesting a requirement for negatively charged lipids during the process of hormone–membrane int

ISSN:0006-3525    

DOI:10.1002/bip.360310610

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe possibility of using molecular dynamics techniques as a tool for simulated annealing is tested in the case of the molecule of biological interest N‐acetyl, N′‐methyl amides of 3(S)‐hydroxy, 4(S)‐amino 6‐methyl heptanoic acid [(3S, 4S)‐statine] and of its (3R,4S) diastereomer. The approach is able to reach global minimum in the conformational space in the case of the mentioned molecule. A description of the method is given. The use of fractional fluctuations of the internal potential energy as an indicator able to point out transition from a given minimum region to a deeper one is investigated. The results about the lowest energy conformation of (3S,4S) diastereomer are in fairly good accordance with the results obtained in the case of search within the whole Conformation

ISSN:0006-3525    

DOI:10.1002/bip.360310611

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

年代:1991

数据来源: WILEY