Solubilized rat liver vitamin K carboxylase demonstrates little selectivity between vitamin K1 and the menaquinones.

Abstract

AbstractThe 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.