A Change in the 3(10)- to alpha-Helical Transition Point in the Heptapeptides Containing Sulfur and Selenium

Duley, Anju and Nethaji, Munirathinam and Ramanathan, Gurunath (2011) A Change in the 3(10)- to alpha-Helical Transition Point in the Heptapeptides Containing Sulfur and Selenium. In: Crystal Growth & Design, 11 (6). pp. 2238-2242.

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Abstract

Crystal structures of three heptapeptides Boc-Ala-Leu-Aib-XXX-Ala-Leu-Aib-OMe (where XXX = methionine in peptide A, selenomethionine in peptide B, and S-benzyl cysteine in peptide C) reveal mixed 3(10)-/alpha-helical conformations with R factors of 6.94, 5.79, and 5.98, respectively. All the structures were solved in the P2(1)2(1)2(1) space group. 3(10)- to a-helical transitions are observed in all of these peptides. The helices begin as a 3(10)-helical segment at the N-terminus and then transit for peptides A and C at residue Aib(3) carbonyl (O(3)), while for peptide B the transition occurs at residue Leu(2) carbonyl oxygen (O(2)). There are water molecules associated in the crystal of each of these peptides and they form different types of hydrogen bonding patterns in each crystal. The observations suggest that 3(10)- to alpha-helical transition is sequence dependent in these short heptapeptide sequences.

Item Type:	Journal Article
Publication:	Crystal Growth & Design
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society.
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	22 Jun 2011 09:36
Last Modified:	22 Jun 2011 09:36
URI:	http://eprints.iisc.ac.in/id/eprint/38434

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