Nagarajaram, HA and Sowdhamini, R and Ramakrishnan, C and Balaram, P (1993) Termination of right handed helices in proteins by residues in left handed helical conformations. In: FEBS Letters, 321 (1). pp. 79-83.
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An analysis of 636 helical segments, ranging in length from 4 to 32 residues, from 123 independent protein crystal structures reveals that helix termmation by residues in left handed (alphaL) helical conformations is a common occurrence. Gly and Asn residues are the most frequent alphaL helix terminators. with the former having a very high propensity to adopt such conformations. The alphaR-alphaR-alphaR-alphaL segment at the C termini of protein helices often possesses a 6 - 1 (N-type) hydrogen bond between the CO of residue i and the NH of residue i + 5 with residue i + 4 occurring in the alphaL conformatron. A stereochemical analysrs 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 alphaL, helix terminating conformations.
|Item Type:||Journal Article|
|Additional Information:||Copyright for this article belongs to Elsevier Science Ltd.|
|Keywords:||Helix termination;6 - 1 Hydrogen bonds;Protein conformation;Protein data analysis|
|Department/Centre:||Division of Biological Sciences > Molecular Biophysics Unit|
|Date Deposited:||06 Dec 2004|
|Last Modified:||06 Jan 2011 09:22|
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