Book of Abstracts: Albany 2007

category image Albany 2007
Conversation 15
June 19-23 2007

DNA Melting Temperature Fluctuations Due to Adsorption and Desorption of Ligands

It is known that the ligands adsorption on DNA leads to shifting of DNA melting temperature. As far as the adsorption is a stochastic process, the number of ligands on DNA is not fixed strictly, but fluctuates around some mean value. This shall lead to the fluctuation of the DNA melting temperature.

In this paper we describe the simplest case of the melting of DNA?s homopolymer, on which the ligands are adsorbed. The double strand of the DNA is presented as one-dimensional crystal. We consider only the case when a ligand can bind only with one adsorption center. The variation of the melting temperature is derived based on the above mentioned assumptions. It is shown that the dependence of variation from the ligand concentration in the solution has a curve form with maximum. At low concentration of ligands the variation of melting temperature linearly grows with the increase of ligand concentration and then, passing the maximum, it decreases and tends to zero at very high values of ligand concentration. This dependence of DNA melting temperature on ligand concentration in the solution is conditioned by the behavior of ligand molecules adsorbed on DNA. When the quantity of ligand molecules on DNA is small, their variation is small as well. With the increase of the quantity of adsorbed ligands their variation shall increase. However, if the quantity of adsorbed ligand molecules is big and close to saturation, the variation shall decrease. It is shown that the binding constant of ligand with DNA can be determined by the coordinate of the maximum variation of DNA melting temperature. The inverse value of ligand concentration at the maximum point equals the binding constant.

V. B. Arakelyan1,*
Z. E. Navoyan2,**

1Yerevan Physics Institute
Alikhanyan Br. st. 2
Yerevan, 0036, Armeni
2Department of Molecular Physics
Yerevan State University
Al. Manukyan st. 1
Yerevan, 0025, Armenia

*Phone: (37410) 350054
Email: arakelv@mail.yerphi.am
**Phone: (37410) 544592
Fax: (37410) 544590
Email: zaven@arminco.com