Structural Dimorphism of Achiral ,-Hybrid Peptide Foldamers: Coexistence of 12-and 15/17-Helices

Misra, Rajkumar and Saseendran, Abhijith and George, Gijo and Veeresh, Kuruva and Raja, K Muruga Poopathi and Raghothama, Srinivasarao and Hofmann, Hans-Joerg and Gopi, Hosahudya N (2017) Structural Dimorphism of Achiral ,-Hybrid Peptide Foldamers: Coexistence of 12-and 15/17-Helices. In: CHEMISTRY-A EUROPEAN JOURNAL, 23 (15). pp. 3764-3772.

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Abstract

Here, novel 12-helices in ,-hybrid peptides composed of achiral -aminoisobutyric acid (Aib) and 4-aminoisocaproic acid (Aic, doubly homologated Aib) monomers in 1:1 alternation are reported. The 12-helices were indicated by solution and crystal structural analyses of tetra- and heptapeptides. Surprisingly, single crystals of the longer nonapeptide displayed two different helix types: the novel 12-helix and an unprecedented 15/17-helix. Quantum chemical calculations on both helix types in a series of continuously lengthened Aib/Aic-hybrid peptides confirm that the 12-helix is more stable than the 15/17-helix in shorter peptides, whereas the 15/17-helix is more stable in longer sequences. Thus, the coexistence of both helix types can be expected within a definite range of sequence lengths. The novel 15/17- and 12-helices in ,-hybrid peptides with 51 and 41 hydrogen-bonding patterns, respectively, can be viewed as backbone-expanded analogues of native - and 3(10)-helices.

Item Type:	Journal Article
Publication:	CHEMISTRY-A EUROPEAN JOURNAL
Publisher:	WILEY-V C H VERLAG GMBH, POSTFACH 101161, 69451 WEINHEIM, GERMANY
Additional Information:	Copy rights for this article belongs to theWILEY-V C H VERLAG GMBH, POSTFACH 101161, 69451 WEINHEIM, GERMANY
Department/Centre:	Division of Chemical Sciences > NMR Research Centre (Formerly Sophisticated Instruments Facility)
Date Deposited:	19 May 2017 10:41
Last Modified:	19 May 2017 10:41
URI:	http://eprints.iisc.ac.in/id/eprint/56683

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