Purification, properties, and partial amino acid sequences of alanine racemase from the muscle of the black tiger prawn Penaeus monodon.
Alanine racemase [EC 5.1.1.1], which catalyzes the interconversion between D- and L-alanine, was purified to homogeneity from the muscle of black tiger prawn Penaeus monodon. The isolated enzyme had a molecular mass of 44 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and 90 kDa on gel filtration, indicating a dimeric nature of the enzyme. The enzyme was highly specific to D- and L-alanine and did not catalyze the racemization of other amino acids. K(m) values toward both D- and L-alanine were almost equal and considerably high compared with those of bacterial enzymes. The purified enzyme retained its activity in the absence of pyridoxal 5'-phosphate as a cofactor but carbonyl reagents inhibited the activity, suggesting the tightly binding of the cofactor to the enzyme protein. Several partial amino acid sequences of peptide fragments of the purified enzyme showed positive homologies from 52 to 76% with bacterial counterparts and a catalytic tyrosine residue of the bacterial enzyme was also retained in the prawn one, indicating alanine racemase gene is well conserved from bacteria to invertebrates.
Yoshikawa
Naoko
N
Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan.
Dhomae
Naoshi
N
Takio
Koji
K
Abe
Hiroki
H
D000411:Alanine Racemase / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D007700:Kinetics; D008969:Molecular Sequence Data; D009132:Muscles / Q000201:enzymology*; D033561:Penaeidae / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid
D000411:Alanine Racemase