hydantoin racemase

{{Infobox enzyme

| Name = Hydantoin racemase

| EC_number = 5.1.99.5

| CAS_number =

| GO_code =

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Hydantoin racemase ({{EnzExplorer|5.1.99.5}}, 5'-monosubstituted-hydantoin racemase, HyuA, HyuE) is an enzyme with systematic name D-5-monosubstituted-hydantoin racemase.{{cite journal | vauthors = Watabe K, Ishikawa T, Mukohara Y, Nakamura H | title = Purification and characterization of the hydantoin racemase of Pseudomonas sp. strain NS671 expressed in Escherichia coli | journal = Journal of Bacteriology | volume = 174 | issue = 24 | pages = 7989–95 | date = December 1992 | pmid = 1459947 | pmc = 207535 }}{{cite journal | vauthors = Wiese A, Pietzsch M, Syldatk C, Mattes R, Altenbuchner J | title = Hydantoin racemase from Arthrobacter aurescens DSM 3747: heterologous expression, purification and characterization | journal = Journal of Biotechnology | volume = 80 | issue = 3 | pages = 217–30 | date = July 2000 | pmid = 10949312 | doi = 10.1016/s0168-1656(00)00262-5 }}{{cite journal | vauthors = Martínez-Rodríguez S, Las Heras-Vázquez FJ, Mingorance-Cazorla L, Clemente-Jiménez JM, Rodríguez-Vico F | title = Molecular cloning, purification, and biochemical characterization of hydantoin racemase from the legume symbiont Sinorhizobium meliloti CECT 4114 | journal = Applied and Environmental Microbiology | volume = 70 | issue = 1 | pages = 625–30 | date = January 2004 | pmid = 14711700 | pmc = 321266 | doi = 10.1128/aem.70.1.625-630.2004 }}{{cite journal | vauthors = Martínez-Rodríguez S, Las Heras-Vázquez FJ, Clemente-Jiménez JM, Rodríguez-Vico F | title = Biochemical characterization of a novel hydantoin racemase from Agrobacterium tumefaciens C58 | journal = Biochimie | volume = 86 | issue = 2 | pages = 77–81 | date = February 2004 | pmid = 15016445 | doi = 10.1016/j.biochi.2004.01.004 | url = https://zenodo.org/record/890549/files/article.pdf }}{{cite journal | vauthors = Suzuki S, Onishi N, Yokozeki K | title = Purification and characterization of hydantoin racemase from Microbacterium liquefaciens AJ 3912 | journal = Bioscience, Biotechnology, and Biochemistry | volume = 69 | issue = 3 | pages = 530–6 | date = March 2005 | pmid = 15784981 | doi = 10.1271/bbb.69.530 }}{{cite journal | vauthors = Martínez-Rodríguez S, Andújar-Sánchez M, Neira JL, Clemente-Jiménez JM, Jara-Pérez V, Rodríguez-Vico F, Las Heras-Vázquez FJ | title = Site-directed mutagenesis indicates an important role of cysteines 76 and 181 in the catalysis of hydantoin racemase from Sinorhizobium meliloti | journal = Protein Science | volume = 15 | issue = 12 | pages = 2729–38 | date = December 2006 | pmid = 17132860 | pmc = 2242435 | doi = 10.1110/ps.062452106 }}{{cite journal | vauthors = Altenbuchner J, Siemann-Herzberg M, Syldatk C | title = Hydantoinases and related enzymes as biocatalysts for the synthesis of unnatural chiral amino acids | journal = Current Opinion in Biotechnology | volume = 12 | issue = 6 | pages = 559–63 | date = December 2001 | pmid = 11849938 | doi = 10.1016/s0958-1669(01)00263-4 }} This enzyme catalyses the following chemical reaction

: D-5-monosubstituted hydantoin $\backslash rightleftharpoons$ L-5-monosubstituted hydantoin

This enzyme is a part of the reaction cascade known as the "hydantoinase process".