ID   5.1.99.5
DE   hydantoin racemase.
AN   5'-monosubstituted-hydantoin racemase.
CA   a D-5-monosubstituted hydantoin = a L-5-monosubstituted hydantoin.
CC   -!- This enzyme, along with EC 3.5.1.77, EC 3.5.1.87 and EC 3.5.2.2,
CC       forms part of the reaction cascade known as the 'hydantoinase
CC       process', which allows the total conversion of D,L-5-monosubstituted
CC       hydantoins into optically pure D- or L-amino acids.
CC   -!- The enzyme from Pseudomonas sp. (HyuE) has a preference for
CC       hydantoins with aliphatic substituents, e.g. D- and L-5-
CC       [2-(methylsulfanyl)ethyl]hydantoin, whereas that from Arthrobacter
CC       aurescens shows highest activity with arylalkyl substituents,
CC       especially 5-benzylhydantoin, at the 5-position.
CC   -!- In the enzyme from Sinorhizobium meliloti, Cys-76 is responsible for
CC       recognition and proton retrieval of D-isomers, while Cys-181 is
CC       responsible for L-isomer recognition and racemization.
DR   Q9F466, HYDRA_PAEAU;  Q00924, HYDRA_PSESN;  Q6TMG4, HYDRA_RHIML;
//