Mediates the vitamin K-dependent carboxylation of glutamate residues to calcium-binding gamma-carboxyglutamate (Gla) residues with the concomitant conversion of the reduced hydroquinone form of vitamin K to vitamin K epoxide. 2,3-epoxyphylloquinone + 4-carboxy-L-glutamyl-[protein] + H(+) + H2O = CO2 + L-glutamyl-[protein] + O2 + phylloquinol Monomer (By similarity). Interacts with CALU. The vitamin K-dependent protein substrates of carboxylase have usually a propeptide that binds to a high-affinity site on the carboxylase. CO(2), O(2) and reduced vitamin K are cosubstrates. Belongs to the vitamin K-dependent gamma-carboxylase family.