Biopolymers and cell. 1986. Volume 2. № 2. 101 - 106
V. I. Ivanov, L. E. Minchenkova, A. K. Shchelkina, B. K. Chernou, A. P. Yartsev, M, P. Kirpichnikov
CONFORMATION OF THE OR3 OPERATOR OF PHAGE K AND ITS FRAGMENT IN AQUEOUS AND AQUEOUS-TRIFLUOROETHANOL SOLUTIONS
Summary
Circular dichroism method (CD) was used to study conformation of the synthetic deoxy-oligonucleotide of 17 base pairs long, which is an On3 operator of phage K, and its 9-base pairs fragment
5' TATCCCTT |GCGGTGATA|
3' ATAGGGAA |CGCCACTAT|
The stability regions of the double-stranded state are determined for these duplexes. Conformations of the short DNA fragments in aqueous solutions of different NaCl concentrations are shown to exist within the limits of B-family. A cooperative change in the CD spectra is observed in trifluoroethanol (TFE) solutions with TFE concentration typical of each oligonucleotide, which is supposed to be due to B-A transition. The B-form stabilization by terminal base pairs is evaluated using the B-A transition theory. Each terminal base pair stabilizes the B form by the value of ~1.7 kcal/mol.