Purification and characterization of serine-glyoxylate aminotransferase from a serine-producing methylotroph, Hyphomicrobium methylovorum GM2.
Serine--glyoxylate aminotransferase was purified to complete homogeneity from a serine-producing methylotrophic bacterium, Hyphomicrobium methylovorum GM2, which possesses the serine pathway. This is the first microbial serine--glyoxylate aminotransferase to be purified. The enzyme has a molecular mass of about 140 kDa and consists of four subunits of identical mass, i.e. 40 kDa. The holoenzyme exhibited absorption maxima at 282 nm and 408 nm, and a shoulder at about 315-345 nm in potassium phosphate pH 7.0; it contained 4 mol pyridoxal 5'-phosphate/mol enzyme. Isoelectric focusing showed that the enzyme had a pI value of 6.9. The Km values for glyoxylate and L-serine were 0.23 mM and 4.98 mM, respectively, and the enzyme showed high specificity for these substrates. The transamination between glyoxylate and L-serine seemed to be nearly irreversible. These data indicated that this serine--glyoxylate aminotransferase plays an essential role in methanol assimilation through the serine pathway in H. methylovorum GM2.
Izumi
Y
Y
Department of Agricultural Chemistry, Faculty of Agriculture, Kyoto University, Japan.
Yoshida
T
T
Yamada
H
H
D001419:Bacteria / Q000201:enzymology*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006038:Glyoxylates / Q000037:antagonists & inhibitors / Q000302:isolation & purification; D007700:Kinetics; D008970:Molecular Weight; D011732:Pyridoxal Phosphate / Q000032:analysis; D012694:Serine / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000302:isolation & purification; D013053:Spectrophotometry; D013379:Substrate Specificity; D000637:Transaminases / Q000037:antagonists & inhibitors / Q000302:isolation & purification*
D006038:Glyoxylates; D012694:Serine; D011732:Pyridoxal Phosphate; D000637:Transaminases; C022636:serine-glyoxylate aminotransferase