title: A Tyrosine Aminomutase from Rice (Oryza sativa) Isomerizes (S)-α- to (R)-β-Tyrosine with Unique High Enantioselectivity and Retention of Configuration.
abstract: A recently discovered 3,5-dihydro-5-methylidene-4H-imidazol-4-one (MIO)-dependent tyrosine aminomutase (OsTAM) from rice [Yan, J., et al. (2015) Plant Cell 27, 1265] converts (S)-α-tyrosine to a mixture of (R)- and (S)-β-tyrosines, with high (94%) enantiomeric excess, which does not change with pH, like it does for two bacterial TAMs. The K(M) of 490 μM and the k(cat) of 0.005 s(-1) are similar for other TAM enzymes. OsTAM is unique and also catalyzes (R)-β- from (S)-α-phenylalanine. OsTAM principally retains the configuration at the reactive C(α) and C(β) centers during catalysis much like the phenylalanine aminomutase on the Taxol biosynthetic pathway in Taxus plants.
authors.forename: Tyler
authors.initials: T
authors.lastname: Walter
authors.affiliation: Medgar Evers College , Brooklyn, New York 11225, United States.
authors.forename: Zayna
authors.initials: Z
authors.lastname: King
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Walker
mesh_terms: D000595:Amino Acid Sequence; D019751:Intramolecular Transferases / Q000737:chemistry / Q000378:metabolism*; D007536:Isomerism; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D012275:Oryza / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D011487:Protein Conformation; D016415:Sequence Alignment; D013237:Stereoisomerism; D013379:Substrate Specificity; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism*
chemical_list: D014443:Tyrosine; D019751:Intramolecular Transferases; C023206:tyrosine 2,3-aminomutase