PREPARATION OF IMMOBILIZED BAKERS YEAST GLUCOSE-6-PHOSPHATE DEHYDROGENASE ATTACHED TO MODIFIED SEPHAROSE AND SEPHADEX AND A COMPARISON OF PROPERTIES OF THESE PREPARATIONS WITH THOSE OF SOLUBLE ENZYME

G-6-P dehydrogenase (D-G-6-P-NADP+ oxidoreductase, EC 1.1.1.49) from Saccharomyces cerevisiae was immobilized on CNBr-activated Sepharose 4B with retention of about 3% of enzyme activity. This uncharged preparation was stable for up to 4 mo. when stored in borate buffer, pH 7.6, at 4.degree. C. Stable enzyme preparations with negative or positive overall charge were made by adding valine or ethylenediamine to the CNBr-activated Sepharose 4B 30 min after addition of the enzyme. These 3 immobilized enzyme preparations retained 40-60% of their activity after 15 min at 50.degree. C. The soluble enzyme is inactivated by these conditions. The soluble enzyme lost 45, and 100% of its activity on incubation for 3 h at pH 6 and 10, respectively. The 3 immobilized-enzyme preparations were completely stable over this entire pH range. The pH optimum of the positively and negatively charged immobilized-enzyme preparations were about 8 and 9, respectively. The soluble enzyme and the uncharged immobilized enzyme had an optimum pH at about 8.5. G-6-P dehydrogenase immobilized on CNBr-activated Sephadex G-25 was unstable, as was enzyme attached to CNBr-activated Sepharose 4B to which glycine, aspartic acid, valine or ethylenediamine was added at the same time as the enzyme.