title: [6-phosphogluconate dehydrogenase of Aspergillus oryzae (Ahlburg). II. Separation and study of isoenzymes].
abstract: Through ammonium sulphate fractionation followed by ion-exchange chromatography, two forms of 6-phosphogluconate dehydrogenase (6j-phosphogluconate: NADP+ oxidoreductase E.C. 1.1.1.44) were isolated from mycelium of Aspergillus oryzae. The Km values for 6PG were the same, but the Km for NADP+ was smaller for isoenzyme I. The Vmx values were also different, with greater activity for isoenzyme II. The optimum pH for isoenzyme I was 7.5. whereas the isoenzyme II had two maximum peaks, at pH 7.5 and 9. Isoenzyme II was the more resistant to thermal inactivation. Inhibition by NADPH was competitive with respect to NADP+, with a Ki value similar for both isoenzymes. The GSSG inhibits isoenzyme I and activates isoenzyme II. The apparent molecular weights determined by gel filtration were 79,000 +/- 2,000 daltons for isoenzyme I and 112,000 +/- 2,000 daltons for isoenzyme II.
mesh_terms: D001230:Aspergillus / Q000201:enzymology*; D001236:Aspergillus oryzae / Q000201:enzymology*; D002852:Chromatography, Ion Exchange; D005978:Glutathione / Q000494:pharmacology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000302:isolation & purification*; D007700:Kinetics; D008970:Molecular Weight; D009249:NADP / Q000494:pharmacology; D010734:Phosphogluconate Dehydrogenase / Q000302:isolation & purification*
chemical_list: D007527:Isoenzymes; D009249:NADP; D010734:Phosphogluconate Dehydrogenase; D005978:Glutathione
vernacular_title: 6-fosfogluconato deshidrogenasa de Aspergillus. II. Separación y estudio de isoenzimas.