Binding causes the remote [5′-3H]thymidine kinetic isotope effect in human thymidine phosphorylase

Matthew R. Birck, Vern L. Schramm

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


The remote 5′-3H V/K kinetic isotope effect (KIE) observed in human thymidine phosphorylase (6.1%) is significantly larger than can be explained by the reaction chemistry. One hypothesis connects the 5′-3H KIE in purine nucleoside phosphorylase to that enzyme's SN1transition state. The transition state of thymidine phosphorylase, however, is an SN2 nucleophilic displacement. Here we report equilibrium binding isotope effects sufficiently large to explain the presence of this substantial KIE in thymidine phosphorylase.

Original languageEnglish (US)
Pages (from-to)6882-6883
Number of pages2
JournalJournal of the American Chemical Society
Issue number22
StatePublished - Jun 9 2004

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry


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