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Role of beta-turn residues in beta-hairpin formation and stability in designed peptides.

Abstract：

:The sequence RGITVNGKTYGR has been reported as part of a de novo design peptide system. This peptide folds as a beta-hairpin structure with three residues per strand and two residue turns. Asn6 side-chain, the residue in position L1 of the beta-turn, appeared to be solvent exposed, interacting only within the turn but not with the rest of the peptide. We have chosen this position as a good candidate to design mutations, based on the protein database statistical abundances, that should mainly affect the turn stability and possibly the pairing between strands. We have found that all NMR parameters, in particular the conformational shift analysis of CalphaH and the coupling constants, 3JHNalpha, correlate very well and show similar conformational features in all the turn mutant peptides. The population estimates are in reasonable agreement among the different methods used. It appears that the peptide with Asn in position L1 is the most structured peptide, followed by the one with Asp6. The next structured peptide is the one with Gly6. The least populated peptides were those with Ala6 and Ser6. We have found a strong correlation between the hairpin population, as determined from the conformational shift of CalphaH and the occurrence of the different residues at position L1 of beta-hairpins with type I' beta-turn, in the protein database. Our analysis demonstrates that this peptide system is sensitive enough to register small energy changes in the hairpin structure; therefore, it constitutes an appropriate model to quantify energy contributions, once the appropriate sheet/coil transition algorithm is developed. Comparison with the other studies indicate that the design of a specific hairpin structure must involve a sequence at the turn region favouring the desired turn type, and a sequence at the strands that avoids alternative interstrand side-chain pairings.

journal_name

J Mol Biol

journal_title

Journal of molecular biology

authors

Ramírez-Alvarado M,Blanco FJ,Niemann H,Serrano L

doi

10.1006/jmbi.1997.1347

subject

Has Abstract

pub_date

1997-11-07 00:00:00

pages

898-912

issue

eissn

0022-2836

issn

1089-8638

pii

S0022-2836(97)91347-4

journal_volume

273

pub_type

杂志文章

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Role of beta-turn residues in beta-hairpin formation and stability in designed peptides.