Effect of n-ethylmaleimide on beef and rat liver vitamin k1 epoxide reductase

Richard B. Silverman*, Dhirendra L. Nandi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


There is little difference in the extent of inactivation of beef liver microsomal vitamin K1 epoxide reductase by N-ethylmaleimide (NEM) whether or not the microsomes are pre-treated with dithiothreitol (DTT). The rat liver microsomal enzyme, however, is inactivated by NEM to a much greater extent if the microsomes are pre-treated with DTT. The beef liver enzyme activity is protected from NEM inactivation by the substrate, vitamin K1 epoxide. Ping-pong kinetics are exhibited by the beef liver enzyme. These results support a mechanism for vitamin K1 epoxide reductase in which the function of the required dithiol is to reduce an active site disulfide bond; however, the geometry of the active sites of the enzyme from rat and beef may be different.

Original languageEnglish (US)
Pages (from-to)289-294
Number of pages6
JournalJournal of Enzyme Inhibition and Medicinal Chemistry
Issue number4
StatePublished - 1990


  • Active site disulfide
  • Dithiothreitol
  • N-ethylmaleimide
  • Ping-pong kinetics

ASJC Scopus subject areas

  • Pharmacology
  • Drug Discovery

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