Stereobiochemical aspects of warfarin isomers for inhibition of enzymatic alkylation of menaquinone-0 to menaquinone-4 in chick liver.

The inhibition of enzymatic activity by the isomers of warfarin for alkylation of menaquinone-0 to menaquinone-4 has been studied in chick liver. Injection of (6,7--3H2)-menaquinone-0 into chicks resulted in the biosynthesis of menaquinone-4 within 3 h. Microsomes of control chicks contained 78 per cent of the total menaquinone-4. (S) (-)-Warfarin and (R) (+)-warfarin isomers inhibited the biosynthesis of menaquinone-4 of about 67 and 17 per cent respectively. Fractionation of soluble microsomal proteins lead to the the isolation of a menaquinone-4 binding protein.