Crystal structure and conformation of the cyclic dipeptide cyclo-(L-histidyl-L-aspartyl) trihydrate

Ramani, R and Venkatesan, K and Marsh, RE (1978) Crystal structure and conformation of the cyclic dipeptide cyclo-(L-histidyl-L-aspartyl) trihydrate. In: Journal Of The American Chemical Society, 100 (3). pp. 949-953.

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Abstract

The crystal structure of cyclo-(L-histidyl-L-aspartyl) trihydrate has been determined by x-ray diffraction techniques, and refined to a final R index of 0.056 for 1601 reflections. The molecule is in a folded conformation, with the imidazole ring facing the diketopiperazine ring. However, since the diketopiperazine ring is essentially planar, the interaction between the two rings is not as intimate as in those cyclic dipeptides in which the diketopiperazine ring is in a boat conformation with the side chain occupying an axial, or flagpole, site. Planarity of the diketopiperazine ring may be dictated by steric interactions between the imidazole ring and the aspartyl side chain. The molecule is a zwitterion, a proton having been transferred from the carboxyl group of the aspartyl side chain to the imidazole ring.

Item Type:	Journal Article
Publication:	Journal Of The American Chemical Society
Publisher:	Amer Chemical Soc
Additional Information:	Copyright of this article belongs to Amer Chemical Soc
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	01 Jan 2010 10:02
Last Modified:	19 Sep 2010 05:49
URI:	http://eprints.iisc.ac.in/id/eprint/24120

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