Biopolym. Cell. 1990; 6(4):43-47.
http://dx.doi.org/10.7124/bc.00027B
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.
  1. Department of Macromolecular Physics, State University of Tbilisi
    Tbilisi, USSR
  2. 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] KÅ‚ysik 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.
[15] Klump HH. Thermodynamics of left-handed helix formation. FEBS Lett. 1986;196(1):175-9.
[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.