Termination of right handed helices in proteins by residues in left handed helical conformations

FEBS Letters

Nagarajaram, H.A.¹  Ramakrishnan, C.¹  Balaram, P.¹  Sowdhamini, R.¹ 

[1] Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India

关键词: Helix termination;    6 → 1 Hydrogen bonds;    Protein conformation;    Protein data analysis;   

DOI  :  10.1016/0014-5793(93)80625-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

An analysis of 636 helical segments, ranging in length from 4 to 32 residues, from 123 independent protein crystal structures reveals that helix termination by residues in left handed (α_L) helical conformations is a common occurrence. Gly and Asn residues are the most frequent α_L helix terminators, with the former having a very high propensity to adopt such conformations. The α_R-α_R-α_R-α_L segment at the C termini of protein helices often possesses a 6 → 1 (π-type) hydrogen bond between the CO of residue i and the NH of residue i + 5 with residue i + 4 occurring in the α_L conformation. A stereochemical analysis of 216 examples shows that in 62 cases the 6 → 1 hydrogen bond is absent. The present analysis provides a quantitative measure of the propensity of the 20 amino acids to adopt α_L helix terminating conformations.

【 授权许可】

Unknown