L-alanine: 4,5-dioxovalerate aminotransferase from Pseudomonas riboflavina: purification and inactivation by methylglyoxal.
L-Alanine:4,5-dioxovalerate aminotransferase, which catalyzes transamination between L-alanine and 4,5-dioxovalerate to yield delta-aminolevulinate and pyruvate, has been purified from Pseudomonas riboflavina IFO 3140. The enzyme had a molecular weight of 190,000 and consisted of four identical subunits. It was crystallized as pale yellow needles. The enzyme used L-alanine (relative activity 100), beta-alanine (39), and L-ornithine (14) as amino donors. gamma-aminobutyrate (55) and epsilon-aminocaproate (34) were also effective as amino donors. The reaction proceeded according to a ping-pong mechanism and the Km values for L-alanine and 4,5-dioxovalerate were 1.7 and 0.75 mM, respectively. The activity of the enzyme is strongly inhibited by pyruvate, hemin, and methylglyoxal. Methylglyoxal interacted with the enzyme and brought about a complete inactivation.
Rhee
H
H
Research Institute for Food Science, Kyoto University, Uji.
Murata
K
K
Kimura
A
A
D000447:Aldehydes / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D008970:Molecular Weight; D011549:Pseudomonas / Q000201:enzymology*; D011765:Pyruvaldehyde / Q000494:pharmacology*; D013056:Spectrophotometry, Ultraviolet; D000637:Transaminases / Q000037:antagonists & inhibitors / Q000302:isolation & purification*
D000447:Aldehydes; D011765:Pyruvaldehyde; D000637:Transaminases; C019687:aminolevulinate aminotransferase