Talk abstracts

Talk on Friday 01:45-02:00pm submitted by Brittany Rauzan

Entropic and enthalpic activation parameters of dodecamer DNA duplex formation is dependent on sequence

Brittany M. Rauzan (Chemistry Department, Allegheny College), Alice Deckert (Chemistry Department, Allegheny College)

Abstract:
The activation parameters, ∆^*H and ∆^*S, for four dodecamers with consistent composition but varying sequence (5’-CACACAAGCGGC-3’/5’-GCCGCTTGTGTG-3’, 5’-CACAAGCGGCAC-3’/5’-GTGCCGCTTGTG-3’, 5’-CAAGCGGCACAC-3’/5’-GTGTGCCGCTTG-3’, 5’-GCGGCAACACAC-3’/5’-GTGTGTTGCCGC-3’) were measured using the stopped-flow technique from 278 K to 303 K. The kinetic profiles were collected over a period of six to eight half-lives and the percentage change in absorbance showed no recognizable correlation with respect to reaction temperature, which indicated complete formation of the duplex. The change in enthalpy of activation ranged from approximately 18 kcal/mol to 27 kcal/mol depending on the sequence. The change in entropy of activation ranged from approximately 31 cal/mol K to 62 cal/mol K. The sequence in which the GC-rich region started at the fifth base-pair had the highest activation parameters, while the sequence in which this region started at the third base-pair position has the lowest activation parameters. The data are interpreted using a model in which the duplex formation is initiation in the GC-rich region.

Keywords: DNA, Activation parameters, Kinetics