Define Vitamin K-dependent carboxylation?

Vitamin K acts as a cofactor in the synthesis of g-carboxyglutamic acid (Gla) from glutamic acid residues required for the normal coagulation of blood. Figure here also illustrates the vitamin K cycle.

The biological role of vitamin K, therefore, is to act as a cofactor for a specific carboxylation reaction that transforms selective glutamate (Glu) residues to g- carboxyglutamate (Gla) residues. The reaction is catalyzed by a microsomal enzyme, g-glutamyl, or vitamin K-dependent carboxylase, which in turn is linked to a cyclic salvage pathway known as the vitamin K epoxide cycle. The hydroquinone (reduced form of vitamin K), COP and 02 are required for the reaction. During the catalysis, hydroquinone is oxidized to vitamin K 2,3-epoxide and the energy derived from the  oxidation drives the carboxylation.