title: Discovery and characterization of D-phenylserine deaminase from Arthrobacter sp. TKS1.
abstract: We discovered a D-phenylserine deaminase that catalyzed the pyridoxal 5'-phosphate (PLP)-dependent deamination reaction from D-threo-phenylserine to phenylpyruvate in newly isolated Arthrobacter sp. TKS1. The enzyme was partially purified, and its N-terminal amino acid sequence was analyzed. Based on the sequence information, the gene encoding the enzyme was identified and expressed in Escherichia coli. The expressed protein was purified to homogeneity and characterized. The enzyme consisted of two identical 46-kDa subunits and showed maximum activity at pH 8.5 and 55°C. The enzyme was stable in the range of pH 7.5 to pH 8.5 and up to 50°C. The enzyme acted on the D-forms of β-hydroxy-α-amino acids, such as D-threo-phenylserine (K(m), 19 mM), D-serine (K(m), 5.8 mM), and D-threonine (K(m), 102 mM). As L-threonine, D-allo-threonine, L-allo-threonine, and DL-erythro-phenylserine were inert, the enzyme could distinguish D-threo-form from among the four stereoisomers of phenylserine or threonine. The enzyme was activated by ZnSO(4), CuSO(4), BaCl(2), and CoCl(2) and strongly inhibited by phenylhydrazine, sodium borohydride, hydroxylamine, and DL-penicillamine. The enzyme exhibited absorption maxima at 280 and around 415 nm. The enzyme has an N-terminal domain similar to that of alanine racemase, which belongs to the fold type III group of pyridoxal enzymes.
authors.affiliation: Multidisciplinary Science Cluster, Research and Education Faculty, Kochi University, B200 Monobe, Nankoku, Kochi, 783-8502, Japan. hmura@kochi-u.ac.jp
authors.forename: Hisashi
authors.initials: H
authors.lastname: Muramatsu
authors.forename: Yuri
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Takeshi
authors.initials: T
authors.lastname: Imai
authors.forename: Sakuko
authors.initials: S
authors.lastname: Ueshima
authors.forename: Jun
authors.initials: J
authors.lastname: Ozaki
authors.forename: Yuji
authors.initials: Y
authors.lastname: Matsui
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Kato
authors.forename: Kouhei
authors.initials: K
authors.lastname: Ohnishi
authors.forename: Norihiro
authors.initials: N
authors.lastname: Kimoto
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Shinji
authors.initials: S
authors.lastname: Nagata
mesh_terms: D000595:Amino Acid Sequence; D001173:Arthrobacter / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004795:Enzyme Stability; D007700:Kinetics; D008190:Lyases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D012694:Serine / Q000031:analogs & derivatives* / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D012694:Serine; D008190:Lyases; C467259:phenylserine