Synthesis of fluoro- and hydroxy-derivatives of vitamin K as substrates or inhibitors of the liver microsomal vitamin K-dependent carboxylase.

The rat liver microsomal vitamin K-dependent carboxylase catalyzes the carboxylation of glutamyl to gamma-carboxyglutamyl residues in the presence of reduced vitamin K, O2 and CO2. The specificity of the enzyme for the vitamin substrate has been probed by the synthesis of a series of fluoro- hydroxy- and methoxy-analogs. 2-Fluoro-methyl-3-phytyl-1,4-naphthoquinone and 2-methyl-3-(1'-fluorodecyl)-1,4-naphthoquinone were synthesized but found to be unstable under enzyme assay conditions. The reduced (naphthohydroquinone) forms of 2-hydroxy-methyl-3-phytyl-1,4-naphthoquinone, 2-methoxymethyl-3-phytyl-1,4-naphthoquinone and 2-methyl-3-(1'-hydroxy-decyl)-1,4-naphthoquinone were inactive as substrates, but inhibitors of the enzyme. The two hydroxy analogs were shown to be low Ki (less than 10 microM) inhibitors of the reduced 2-methyl-3-phytyl-1,4-naphthoquinone-dependent activity of the enzyme. The oxidized forms of these compounds did not inhibit the enzyme and they had no activity as in vivo anticoagulants.