Artificial Cell Immobilized Multienzyme Systems and Cofactors

Abstract

The biomedical applications of immobilized enzymes have already been demonstrated using single enzyme systems (1–3). However, most metabolic functions are carried out in the body by complex multienzyme systems with cofactor requirements. As a result, research has been carried out here for microencapsulation of multienzyme systems with cofactor regeneration incorporated. Artificial cells containing hexokinase and pyruvate kinase could recycle ATP for the continuous conversion of glucose into G-6-P (4,5). Artificial cells containing alcohol dehydrogenase and malic dehydrogenase can recycle NADH (4,5). Multienzyme systems (urease, glutamate dehydrogenase, glucose-6-phosphate dehydrogenase) inside semipermeable microcapsules can convert urea sequentially into ammonia and glutamate (6). Glucose-6-phosphate dehydrogenase is used to recycle the cofactor. In order to allow for the use of blood glucose, artificial cells containing urease, glutamine dehydrogenase, and glucose dehydrogenase have been developed to convert urea or ammonia into glutamate (7,8).