Carnosine synthase

Carnosine synthase (EC 6.3.2.11) is an enzyme that catalyzes the chemical reaction

ATP + L-histidine + beta-alanine ${\displaystyle \rightleftharpoons }$ ADP + phosphate + carnosine

The 3 substrates of this enzyme are ATP, L-histidine, and beta-alanine, whereas its 3 products are ADP (previously thought to form AMP^[1]), diphosphate, and carnosine.

This enzyme belongs to the family of ligases, specifically those forming carbon-nitrogen bonds as acid-D-amino-acid ligases (peptide synthases). The systematic name of this enzyme class is 'L-histidine:beta-alanine ligase (AMP-forming)' (incorrect on AMP-forming^[2]). Other names in common use include 'carnosine synthetase', 'carnosine-anserine synthetase', 'homocarnosine synthetase', and 'carnosine-homocarnosine synthetase'.

The gene encoding this enzyme has been identified by Jakub Drozak and coworkers in 2010.^[3] The gene encoding the Carnosine synthase is ATPGD1, a member of the “ATP-grasp family” of ligases. Because of its involvement in the formation of carnosine, this gene is now also named 'CARNS1'.^[4]

• KALYANKAR GD, MEISTER A (1959). "Enzymatic synthesis of carnosine and related beta-alanyl and gamma-aminobutyryl peptides". J. Biol. Chem. 234 (12): 3210–8. doi:10.1016/S0021-9258(18)69651-6. PMID 14404206.
• Stenesh JJ; Winnick T (1960). "Carnosine–anserine synthetase of muscle. 4. Partial purification of the enzyme and further studies of β-alanyl peptide synthesis". Biochem. J. 77 (3): 575–581. doi:10.1042/bj0770575. PMC 1205078. PMID 16748858.