Identification of vitamin K side chain cleavage enzyme

Vitamin K taken from the diet is PK, but most of the vitamin K present in the tissue is MK-4. We have demonstrated that PK has a side chain cleaved in the small intestine to become an intermediate MD, which is converted to MK-4 by UBIAD1 in tissues and exhibits various physiological activities. However, the mechanism of side-chain cleavage to MD is not clear, and the whole picture of 'vitamin K metabolism dynamics' is not yet clear. In this study, we aim to understand the metabolism mechanism of vitamin K and search for and identify vitamin K side-chain cleaving enzymes. From the results of this study, if the mechanism of conversion to MK-4 can be clarified, the significance of vitamin K metabolic conversion will be clarified. In the future, it is expected to lead to the development of effective methods of ingesting nutrients and new drugs.