Category:Complex:carbamoyl phosphate synthetase
About
Description (originally from EcoCyc[1][2]) carbamoyl phosphate synthetase
Comments (originally from EcoCyc[1][2]) Carbamoyl phosphate synthase catalyzes reactions in the biosynthesis of pyrimidine nucleotides and arginine. The enzyme is a tetramer of heterodimers. The small subunit has amidotransferase activity and the large subunit has synthetase activity.
The assembly of carbamoyl phosphate requires at least four separate chemical reactions: phosphorylation of bicarbonate to carboxyphosphate; hydrolization of glutamine to glutamate and ammonia; a nucleophilic attack of ammonia on carboxyphosphate yielding carbamate; and finally the phosphorylation of carbamate forming carbamoyl phosphate.
In addition to the Mg+2 needed to complex with the nucleotide substrate, free Mg+2 is an absolute requirement for activity. Other ions also bind at the divalent cation site and the nucleotide site. [3][4]
References
- ↑ 1.0 1.1 EcoCyc (release 10.6; 2007) Keseler, IM et al. (2005) Nucleic Acids Res. 33(Database issue):D334-7
- ↑ 2.0 2.1 EcoCyc (release 11.1; 2007) Keseler, IM et al. (2005) Nucleic Acids Res. 33(Database issue):D334-7
- ↑ Raushel, FM et al. (1979) Paramagnetic probes for carbamoyl-phosphate synthetase: metal ion binding studies and preparation of nitroxide spin-labeled derivatives. Biochemistry 18 5562-6 PubMed
- ↑ Thoden, JB et al. (1999) The structure of carbamoyl phosphate synthetase determined to 2.1 A resolution. Acta Crystallogr. D Biol. Crystallogr. 55 8-24 PubMed
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