Vitamin K epoxide reductase: Evidence that Vitamin K dihydroquinone is a product of Vitamin K epoxide reduction

Abstract

Vitamin K epoxide reductase is a two component enzyme activity which catalyzes the reduction of Vitamin K epoxide using dithiothreitol as either a primary or secondary source of reducing equivalents. A high performance liquid chromatographic assay system indicates that in addition to the quinone, the dihydroquinone form of Vitamin K is a reaction product. Carboxymethyl cellulose chromatography suggests that the same cytosolic protein fraction may be involved in the dithiothreitol-supported reduction of Vitamin K epoxide, the dithiothreitol-supported reduction of Vitamin K quinone and the NADH-supported reduction of dichlorophenol-indophenol. © 1981.