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Publication Abstract from PubMed

The 60-fold reduced phosphorylation rate of azidothymidine (AZT) monophosphate (AZTMP), the partially activated AZT metabolite, by human thymidylate kinase (TMPK) severely limits the efficacy of this anti-HIV prodrug. Crystal structures of different TMPK nucleotide complexes indicate that steric hindrance by the azido group of AZTMP prevents formation of the catalytically active closed conformation of the P-loop of TMPK. The F105Y mutant and a chimeric mutant that contains sequences of the human and Escherichia coli enzyme phosphorylate AZTMP 20-fold faster than the wild-type enzyme. The structural basis of the increased activity is assigned to stabilization of the closed P-loop conformation.

Potentiating AZT activation: structures of wild-type and mutant human thymidylate kinase suggest reasons for the mutants' improved kinetics with the HIV prodrug metabolite AZTMP.,Ostermann N, Lavie A, Padiyar S, Brundiers R, Veit T, Reinstein J, Goody RS, Konrad M, Schlichting I J Mol Biol. 2000 Nov 17;304(1):43-53. PMID:11071809^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.