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Thermodynamics of polymolecular duplexes between phosphate‐methylated DNA and natural DNA
Author(s) -
Moody Maurice R.,
van Genderen Marcel H. P.,
Buck Henk M.
Publication year - 1990
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360300513
Subject(s) - chemistry , dna , enthalpy , phosphate , entropy (arrow of time) , duplex (building) , melting temperature , chemical stability , thermodynamics , crystallography , stereochemistry , biochemistry , organic chemistry , physics , materials science , composite material
Phosphate‐methylated (P.M.) DNA possesses a very high affinity for complementary natural DNA, as a result of the absence of interstrand electrostatic repulsions. In this study, a model system phosphate‐methylated d[C n ] with natural d(G k ) ( n < k )is chosen for an investigation of the thermodynamic properties that determine duplex stability. The enthalpy change of a melting transition is shown to be considerably larger than is observed for corresponding natural DNA duplexes. It is found that ΔH 0 nof GG/CC nearest neighbor pairwise interaction equals −15.6 kcal/mol, compared to −11.0 kcal/mol for the natural analog. The entropy change is strongly dependent on the length of the natural DNA strand and the number of phosphate‐methylated DNA oligomers hybridized. The results are explained by means of a model in which a cooperative effect for subsequent hybridizations of phosphate‐methylated DNA oligomers is assumed, thus giving additional stability.