An exploratory ab initio conformational analysis of selected fragments of nicotinamide adenine dinucleotide (NAD+).: Part II:: adenosine

Ab initio molecular orbital computations were carried out on selected fragments of nicotinamide adenine dinucleotide (NAD(+)) at the RHF/3-21G level of theory. The definitions of the relative spatial orientation of all constituent atomic nuclei have been formulated in such a modular fashion so as to allow for portions of the whole to be studied independently. Key points of examination included the rotation of adjacent moieties and ring puckering. This work focuses on the possible conformations of the adenosine moiety. It is anticipated that the structural results from the truncated and modified fragments will closely resemble those of NAD as a whole. (C) 2003 Elsevier B.V. All rights reserved.