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Stereo‐selectivity of HIV‐1 reverse transcriptase toward isomers of thymidine‐5′‐O‐1‐thiotriphosphate
Author(s) -
Radzio Jessica,
SluisCremer Nicolas
Publication year - 2005
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.051445605
Subject(s) - reverse transcriptase , thymidine , chemistry , selectivity , stereochemistry , dissociation (chemistry) , dissociation constant , dna , enzyme , rna , gene , catalysis , biochemistry , organic chemistry , receptor
The first pre‐steady‐state kinetic analysis of the stereo‐selective incorporation of Rp‐ and Sp‐isomers of thymidine‐5′‐O‐1‐thiotriphosphate (TTPαS) by HIV‐1 reverse transcriptase (RT) is reported. Rates of polymerization (k pol ), apparent dissociation constants (K d ), and substrate specificities (k pol /K d ) were measured for TTP, Rp‐TTPαS, and Sp‐TTPαS in the presence of Mg 2+ , Mn 2+ , and Co 2+ . HIV‐1 RT exhibits a strong preference to incorporate Sp‐TTPαS over Rp‐TTPαS in the presence of Mg 2+ ; however, this stereo‐selective preference was decreased when Mg 2+ was replaced with Mn 2+ and Co 2+ . Furthermore, HIV‐1 RT exhibited no phosphorothioate elemental effects for the incorporation of Sp‐TTPαS, but large elemental effects were calculated for Rp‐TTPαS for each of the metals tested. These results are discussed in relation to our current understanding of the RT active‐site structure and the mechanism of DNA synthesis.