Candida delta-aminovalerate: alpha-ketoglutarate aminotransferase: purification and enzymologic properties

A new enzyme that catalyzes the transamination of delta-aminovalerate with alpha-ketoglutarate was purified to homogeneity from adapted cells of Candida guilliermondii var. membranaefaciens. The relative molecular mass determined by gel filtration was estimated to be close to 118,000. The transaminase behaved as a dimer with two similar subunits in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme has a maximum activity in the pH range of 7.8-8.5 and at 40 degrees C. alpha-Ketoglutarate and to a lesser extent pyridoxal 5'-phosphate were effective protecting agents toward temperature raising. The enzyme exhibits absorption maximum at 330 and 410 nm. The enzyme catalyzes the transamination between omega-amino acids and alpha-ketoglutarate. delta-Aminovaleric acid is the best amino donor. The Km values for delta-aminovalerate, alpha-ketoglutarate, and pyridoxal 5'-phosphate determined from the Lineweaver-Burk plot were 4.9 mM, 3.6 mM, and 22.7 microM, respectively. The inhibitory effect of various amino acids analogues on the transamination reaction between delta-aminovalerate and alpha-ketoglutarate was studied, and Ki values were determined.