Biopolym. Cell. 1990; 6(4):43-47.
Structure and Function of Biopolymers
Energetics of the B-to-Z and Zhelix-to-coil transitions in water solutions of Poly(DG-DC)
1Mrevlishvili G. M., 1Lapiashvili G. N., 1Mdzinarashvili T. J., 2Gorgoshidze M. Z., 2Kharatishvili M. G., 1Yakobashvili N. E.
- Department of Macromolecular Physics, State University of Tbilisi
Tbilisi, USSR - Institute of Physics, Academy of Sciences of the Georgian SSR
Tbilisi, USSR
Abstract
Differential scanning calorimetry, CD- and UV-spectroscopy were used to study thermodynamics of the B-Z and Z-helix-coil transitions of poly(dG-dC). The experiments were performed under conditions of 0.5 mM water solutions of sodium cacodylate (pH 6.5) + 1 mM MgCl2 + 0.02 mM EDTA. The reversible transition of the polymer observed calorimetrically at 76 °C was identified as B-Z transition. The left-handed helix-coil transition was observed at 97 °C. The enthalpy of B-Z transition is small. A//Cai = 0.2 ± 0.02 kcal/mole bp, indicating a fine energy balance between the DNA left- and right-handed conformations in water solutions. The enthalpy of Z-helix-coil transition is A//Cai=10.1 ± l.l kcal/mole bp.
Full text: (PDF, in Russian)
References
[1]
Pohl FM, Jovin TM. Salt-induced co-operative conformational change of a synthetic DNA: equilibrium and kinetic studies with poly (dG-dC). J Mol Biol. 1972;67(3):375-96.
[2]
Wang AH, Quigley GJ, Kolpak FJ, Crawford JL, van Boom JH, van der Marel G, Rich A. Molecular structure of a left-handed double helical DNA fragment at atomic resolution. Nature. 1979;282(5740):680-6.
[3]
Kłysik J, Stirdivant SM, Wells RD. Left-handed DNA. Cloning, characterization, and instability of inserts containing different lengths of (dC-dG) in Escherichia coli. J Biol Chem. 1982;257(17):10152-8.
[4]
Nordheim A, Rich A. Negatively supercoiled simian virus 40 DNA contains Z-DNA segments within transcriptional enhancer sequences. Nature. 1983 Jun 23-29;303(5919):674-9.
[5]
Arndt-Jovin DJ, Robert-Nicoud M, Zarling DA, Greider C, Weimer E, Jovin TM. Left-handed Z-DNA in bands of acid-fixed polytene chromosomes. Proc Natl Acad Sci U S A. 1983;80(14):4344-8.
[6]
Ivanov VI, Krylov DYu, Minyat EE. Three-state diagram for DNA. J Biomol Struct Dyn. 1985;3(1):43-55.
[7]
Minyat EE, Karapetyan AT, Vardevanyan PO, Ivanov VI. Phase surface of the B–Z equilibrium for poly[d(G–C)] solution in coordinates: non-electrolyte fraction, ionic strength, temperature. Biopolym Cell. 1988; 4(4):177-82.
[8]
Behe MJ, Felsenfeld G, Szu SC, Charney E. Temperature-dependent conformational transitions in poly(dG-dC) and poly(dG-m5dC). Biopolymers. 1985;24(2):289-300.
[9]
Chaires JB, Sturtevant JM. Thermodynamics of the B to Z transition in poly(m5dG-dC). Proc Natl Acad Sci U S A. 1986;83(15):5479-83.
[10]
Privalov PL. Physical problems of protein structure. Vestn. Akad. Nauk. SSSR. 1986; (2):72-9.
[11]
Cantor CR, Schimmel PR. Biophysical Chemistry. San Francisco, WH Freeman and Co., 1985; Vol. 3, 534 p.
[12]
Rich A, Nordheim A, Wang AH. The chemistry and biology of left-handed Z-DNA. Annu Rev Biochem. 1984;53:791-846.
[13]
Chevrier B, Dock AC, Hartmann B, Leng M, Moras D, Thuong MT, Westhof E. Solvation of the left-handed hexamer d(5BrC-G-5BrC-G-5 BrC-G) in crystals grown at two temperatures. J Mol Biol. 1986;188(4):707-19.
[14]
Saenger W. Principles of nucleic acid structure. New York: Springer, 1984; 556 p.
[16]
Ruggiero J, Manzini G, Quadrifoglio F. Ionic and nonionic contributions to the free-energy change in the B-Z transition of alternating polydeoxynucleotides in aqueous solution. Biopolymers. 1987;26(11):1975-9.
[17]
Hall KB, Maestre MF. Temperature-dependent reversible transition of poly(dCdG).poly(dCdG) in ethanolic and methanolic solutions. Biopolymers. 1984;23(11 Pt 1):2127-39.
