Open AccessConformational analysis of the B and Z forms of the d(m 5 C‐G) 3 and d(br 5 C‐G) 3 hexamers in solution
Author(s) -
ORBONS Leonard P. M.,
ALTONA Cornelis
Publication year - 1986
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1986.tb09950.x
Subject(s) - chemistry , crystallography , guanosine , stereochemistry , z dna , nuclear magnetic resonance spectroscopy , crystal structure , dna , biochemistry
The B and the Z forms of the DNA hexamers d(m 5 C‐G) 3 and d(br 5 C‐G) 3 were investigated by means of NMR spectroscopy. It is demonstrated that the low‐salt form of d(m 5 C‐G) 3 is a B DNA structure. The form, which becomes increasingly predominant when increasing amounts of MgCl 2 and/or methanol are added to the solution, has Z DNA characteristics. It is shown that the major geometrical features of the Z form of d(m 5 C‐G) 3 in the crystal structure are maintained in solution, with the dC residues S sugar conformation, γ + and the base in the anti orientation and the dG residues N (except the 3′‐terminal residue), γ t and syn. Neither the Z form of the methylated nor that of the brominated compound resembles the Z′ form, in which the deoxy guanosine sugar rings adopt a C1′‐ exo conformation. Substitution of m 5 C by br 5 C causes no perceptible conformational changes in either the B or in the Z forms.