Preferred Conformation of C-Lactose at the Free and Peanut Lectin Bound States

Ravishankar, R and Surolia, A and Vijayan, M and Lim, Sungtaek and Kishi, Yoshito (1998) Preferred Conformation of C-Lactose at the Free and Peanut Lectin Bound States. In: Journal of the American Chemical Society, 120 (44). pp. 11297-11303.

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Abstract

A conformational analysis of methyl -C-lactoside (5) is carried out (Table 1), which suggests the preferred solution conformation of 5 to be described as a mixture of conformers A ( = 300; = 60) and B ( = 300; = 300) to a first approximation. Applying a modified Karplus equation for the vicinal coupling constants observed for the H.a and H.1' protons of 5, the dihedral angle ( = O.5'-C.1'-C.a-C.4) was deduced to be approximately +280. Nuclear Overhauser effect (NOE) experiments were then conducted on 5-D2 and its parent methyl -O-lactoside in a 7:3 mixture of pyridine-d5 and methanol-d4, qualitatively demonstrating that the conformational characteristics of both methyl -C- and -O-lactosides at the free states are represented as a mixture of two conformers A and B, but their relative population may be different. Through X-ray analysis, it has been definitively established that the conformation ( = 297(7) and = 120(2)) of C-lactose bound to peanut lectin is practically identical to the conformation ( = 291(6) and = 118(9)) of its parent O-lactose bound to the same protein.

Item Type:	Journal Article
Publication:	Journal of the American Chemical Society
Publisher:	American Chemical Society
Additional Information:	The copyright of this article belongs to the American Chemical Society
Keywords:	c lactose;peanut lectin;bound states;conformation analysis
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	27 Aug 2004
Last Modified:	19 Sep 2010 04:14
URI:	http://eprints.iisc.ac.in/id/eprint/1347

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