Characterization of three enzymatic forms of glucose-6-phosphate dehydrogenase from Aspergillus oryzae.
Three forms (I, II and III) of glucose-6-phosphate dehydrogenase were isolated from mycelium of Aspergillus oryzae grown on ribose as the carbon source, by ion-exchange chromatography. The Km values determined for the three forms with respect to glucose-6-phosphate were nearly identical; however the Km for NADP+ were different and the Vmax for the isoenzymatic form II was higher than those for I and III. Inhibition by NADPH was competitive with respect to NADP+, isoenzyme II showing the highest Ki. The optimum pH for forms I, II and III were 9.0, 8.0 and 8.5, respectively, and form I was more thermostable than the others. The apparent molecular weights, determined by gel filtration, were 92,000, 117,500 and 141,000 for forms I, II and III, respectively.
Cebrián-Pérez
J A
JA
Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Veterinaria, Zaragoza, Spain.
Muiño-Blanco
T
T
Pérez-Martos
A
A
López-Pérez
M J
MJ
D001230:Aspergillus / Q000201:enzymology*; D001236:Aspergillus oryzae / Q000201:enzymology*; D005954:Glucosephosphate Dehydrogenase / Q000037:antagonists & inhibitors / Q000302:isolation & purification*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000302:isolation & purification*; D007700:Kinetics; D008970:Molecular Weight; D009249:NADP / Q000494:pharmacology
D007527:Isoenzymes; D009249:NADP; D005954:Glucosephosphate Dehydrogenase