Function
Ornithine carbamoyltransferase (OTC) catalyzes the conversion of carbamoyl phosphate (CP) and ornithine to citrulline and phosphate. OTC is part of the arginine biosynthesis in plants and bacteria and part of the urea cycle in mammals[1]. Norvaline is a competitive inhibitor of OTC. The anabolic OTC catalyzes the citrulline synthesis while the catabolic OTC catalyzes the citrulline phosphorolysis.
For details see Sanbox Reserved 684.
Disease
OTC deficiency is a genetic urea cycle disorder[2].
Structural highlights
The biological assembly of OTC is homotrimer. OTC structure contains an N-terminal - CP-binding domain and a C-terminal - ornithine binding domain. OCT active site is situated between the two domains[3].
3D structures of ornithine carbamoyltransferase
Ornithine carbamoyltransferase 3D structures
- ↑ Murata LB, Schachman HK. Structural similarity between ornithine and aspartate transcarbamoylases of Escherichia coli: characterization of the active site and evidence for an interdomain carboxy-terminal helix in ornithine transcarbamoylase. Protein Sci. 1996 Apr;5(4):709-18. PMID:8845761 doi:https://dx.doi.org/10.1002/pro.5560050416
- ↑ Storkanova G, Vlaskova H, Chuzhanova N, Zeman J, Stranecky V, Majer F, Peskova K, Luksan O, Jirsa M, Hrebicek M, Dvorakova L. Ornithine carbamoyltransferase deficiency: molecular characterization of 29 families. Clin Genet. 2013 Dec;84(6):552-9. doi: 10.1111/cge.12085. Epub 2013 Feb 7. PMID:23278509 doi:https://dx.doi.org/10.1111/cge.12085
- ↑ Sankaranarayanan R, Cherney MM, Cherney LT, Garen CR, Moradian F, James MN. The crystal structures of ornithine carbamoyltransferase from Mycobacterium tuberculosis and its ternary complex with carbamoyl phosphate and L-norvaline reveal the enzyme's catalytic mechanism. J Mol Biol. 2008 Jan 25;375(4):1052-63. Epub 2007 Nov 19. PMID:18062991 doi:10.1016/j.jmb.2007.11.025
