Amino acid pairing at the N- and C-termini of helical segments in proteins

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Nuno A. Fonseca (Author) Other; Rui Camacho (Author) FEUP; A. L. de Magalhães (Author) FCUP

Journal

Title: Proteins: Structure, Function and Genetics

Vol. 70 No. 1

Pages: 188-196

ISSN: 0887-3585

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 23 Citations

Scopus - 25 Citations

Scientific classification

FOS: Natural sciences > Biological sciences

Other information

Authenticus ID: P-004-4P3

DOI: 10.1002/prot.21525

Abstract (EN): A systematic survey was carried out in an unbiased sample of 815 protein chains with a maximum of 20% homology selected from the Protein Data Bank, whose structures were solved at a resolution higher than 1.6 angstrom and with a R-factor lower than 25%. A set of 5556 subsequences with a-helix or 3(10)-helix motifs was extracted from the protein chains considered. Global and local propensities were then calculated for all possible amino acid pairs of the type (i, i + 1), (i, i + 2), (i, i + 3), and (i, i + 4), starting at the relevant helical positions N1, N2, N3, C3, C2, C1, and N-int (interior positions), and also at the first nonhelical positions in both termini of the helices, namely, N-cap and C-cap. The statistical analysis of the propensity values has shown that pairing is significantly dependent on the type of the amino acids and on the position of the pair. A few sequences of three and four amino acids were selected and their high prevalence in helices is outlined in this work. The Glu-Lys-Tyr-Pro sequence shows a peculiar distribution in proteins, which may suggest a relevant structural role in alpha-helices when Pro is located at the C-cap position. A bioinformatics tool was developed, which updates automatically and periodically the results and makes them available in a web site.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 9