Dependence of the Transition Temperatures of DNA Molecules upon Their Base Compositions

Abstract

Thermal denaturation and renaturation processes of DNA-type molecules are studied, using two models of DNA-type double-chain which were previously treated by Zimm and Hill. In these two models, the difference between the bond energies of the two kinds of base pairs, guanine-cytosine and adenine-thymine, is taken into account, assuming the random sequences of four bases in the double-chain. Then it can be shown that the two models have essentially different characters for the dependence of transition temperature upon the guanine+cytosine content. The first model gives an almost linear relationship between the transition temperature and guanine+cytosine content, but the second gives an almost quadratic relationship. These results are discussed, using the experimental data given by Marmur and Doty, and Eigner.