Reaction: peptidyl-4-carboxyglutamate + 2,3-epoxyphylloquinone + H2O = peptidyl-glutamate + CO2 + O2 + phylloquinol
For diagram of reaction click here and mechanism click here.
Other name(s): vitamin K-dependent carboxylase; γ-glutamyl carboxylase; peptidyl-glutamate 4-carboxylase (2-methyl-3-phytyl-1,4-naphthoquinone-epoxidizing)
Systematic name: peptidyl-glutamate 4-carboxylase (2-methyl-3-phytyl-1,4-naphthoquinol-epoxidizing)
Comments: The enzyme can use various vitamin-K derivatives, including menaquinol, but does not contain iron. The mechanism appears to involve the generation of a strong base by oxygenation of vitamin K. It catalyses the post-translational carboxylation of glutamate residues of several proteins of the blood-clotting system. 9–12 glutamate residues are converted to 4-carboxyglutamate (Gla) in a specific domain of the target protein. The 4-pro-S hydrogen of the glutamate residue is removed [5] and there is an inversion of stereochemistry at this position [6].
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:
References:
1. Dowd, P., Hershline, R., Ham, S.W. and Naganathan, S. Vitamin K and energy transduction: a base strength amplification mechanism. Science 269 (1995) 1684-1691. [PMID: 7569894]
2. Furie, B., Bouchard, B.A. and Furie, B.C. Vitamin K-dependent biosynthesis of γ-carboxyglutamic acid. Blood 93 (1999) 1798-1808. [PMID: 10068650]
3. Rishavy, M.A., Hallgren, K.W., Yakubenko, A.V., Shtofman, R.L., Runge, K.W. and Berkner, K.L. Bronsted analysis reveals Lys218 as the carboxylase active site base that deprotonates vitamin K hydroquinone to initiate vitamin K-dependent protein carboxylation. Biochemistry 45 (2006) 13239-13248. [PMID: 17073445]
4. Silva, P.J. and Ramos, M.J. Reaction mechanism of the vitamin K-dependent glutamate carboxylase: a computational study. J. Phys. Chem. B 111 (2007) 12883-12887. [PMID: 17935315]