Solubilized Rat Liver Vitamin K Carboxylase Demonstrates Little Selectivity between Vitamin K 1 and the Menaquinones

Abstract

Abstract

The ability of vitamin K₁ and the menaquinones, MK-1 to MK-10, to promote K-dependent carboxylation has been determined with Triton X-100-solubilized liver microsomes from vitamin K-deficient rats. All menaquinones were found to be effective in promoting vitamin K-dependent carboxylation. There were only slight differences observed in the maximum level of carboxylation given by vitamin K₁ and the menaquinones. There was also little difference in the concentrations required to produce a given level of carboxylation. Therefore, the detergent-solubilized vitamin K carboxylase shows little selectivity between vitamin K₁ and the menaquinones. The vitamin K carboxylase apparently utilizes any one of the natural vitamin K compounds equally as well as any other, once the vitamin K reaches the membrane-bound carboxylase.