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Aromatic L-Amino Acid Decarboxylase from Micrococcus percitreus Purification, Crystallization and Properties
Nakazawa, Hidetsugu,Kumagai, Hidehiko,Yamada, Hideaki
, p. 2543 - 2552 (2007/10/02)
An aromatic L-amino acid decarboxylase was crystallized from the cell free extract of Micrococcus percitreus.The purification procedure included protamine sulfate treatment, ammonium sulfate fractionation, DEAE-Sephadex column chromatography and Sephadex G-200 filtration.Crystals were obtained from a solution of the purified enzyme by addition of ammonium sulfate.The crystalline enzyme preparation was homogeneous as judged by ultracentrifugation and SDS-polyacrylamide gel electrophoresis.The molecular weight was determined to be approximately 101,000.The enzyme was evidently composed of two identical subunits of a molecular weight of 48,000.The enzyme catalyzed the stoichiometric conversion of L-tryptophan to tryptamine and CO2 in the presence of pyridoxal phosphate.The optimum pH was 9.0 for the conversion.The Km value and the maximum velocity of L-tryptophan decarboxylation were 2.4E-3 M and 44 μmol/min/mg of protein, respectively.This enzyme also catalyzed decarboxylation of 5-hydroxy-L-tryptophan, L-phenylalanine, L-tyrosine, 3,4-dihydroxy-L-phenylalanine, L-kynurenine and thier α-methyl amino acid derivatives.
