THE INFLUENCE OF ENZYME CONCENTRATION ON THE ENCAPSULATION OF GLUTAMATE-DEHYDROGENASE AND ALCOHOL-DEHYDROGENASE IN RED-BLOOD-CELLS

Glutamate dehydrogenase (GDH) and alcohol dehydrogenase (ADH) have bee n encapsulated in sheep and human red blood cells (RBCs) by a hypotoni c dialysis/isotonic resealing procedure. At a fixed enzyme level in th e dialysis bag (100 units/ml of RBCs), a significant encapsulation yie ld was observed for ADH, both in human (17.2%) and sheep (47.9%) RBCs, whereas a very low entrapment of GDH was achieved (1-3%) in either sp ecies. Carrier cell recovery was 61-65% in humans and 30-34% in sheep. Because of the aggregation of GDH to large polymers at protein levels above 1 mg/ml, the yield of encapsulation and the specific activity i n human carrier RBCs were compared at different enzyme concentrations. While entrapment was not affected by differences in ADH up to 13 000 units/ml of RBCs (38 mg/ml), the yield of GDH encapsulation significan tly decreased as the enzyme level increased up to 750 units/ml of RBCs (15 mg/ml), thus demonstrating the importance of protein concentratio n in the encapsulation process for those enzymes that tend to aggregat e.