Changes in poly[d(T-G).d(C-A)] chirality due to Hg(II)-binding: circular dichroism (CD) studies.
The conformation of poly[d(T-G).d(C-A)] in aqueous solution (0.1 M NaClO4, 5 mM cacodylic acid buffer, pH 6.9) was studied by circular dichroism (CD) spectroscopy in the ultraviolet. The conformation of the polynucleotide, as reflected by its chiroptical signature, changes in a highly cooperative fashion in the presence of Hg(ClO4)2. The CD changes signal transitions first from the B to a modified B-state (B*), or to a non-B structure termed X, and finally to a form that is presumably Z. The alterations are totally reversible subsequent to the removal of mercury with the help of a suitable complexing agent such as sodium cyanide, indicating that mercuration does not disrupt Watson-Crick hydrogen bonding to any extent.
Department of Food Science and Technology, University of California, Davis 95616.
D W
DW
Gruenwedel
M K
MK
Cruikshank
D002942:Circular Dichroism; D008628:Mercury; D009690:Nucleic Acid Conformation; D011089:Polydeoxyribonucleotides / Q000737:chemistry*; D012996:Solutions; D013237:Stereoisomerism
D011089:Polydeoxyribonucleotides; D012996:Solutions; C044165:poly(d(G-T).d(C-A)); D008628:Mercury