S. Ginell, R. Parthasarathy
Oct 30, 1978
Citations
1
Influential Citations
14
Citations
Journal
Biochemical and biophysical research communications
Abstract
Abstract The crystal structure of N2-methylguanosine (m2G), a modified nucleoside of tRNA, has been determined from three-dimensional x-ray diffractometer data. The N2-methyl substituent in the crystal structure is proximal to the imidazole ring, though in solution, it shows no restricted rotation across the CN bond. From a comparison of the earlier crystal structure studies of G and m22G with m2G, it is found that the methylation of the 2-amino group leads to altered stacking and conformation of the nucleoside. The methyl groups play a predominant role in the stacking of the bases. The molecules of m2G and m22G both have the syn conformation across the glycosidic bond despite the lack of 0(5′) H…N(3) hydrogen bond. Also, both the methylated molecules exhibit non-standard conformations across the C(4′)C(5′) bond. It is suggested that such alterations in the stacking and conformation of m2G, rather than destabilization of the Watson-Crick hydrogen bonding, is important in the biological role of m2G as a part of the DHU stem of tRNA.