title: Conversion of ammonia or urea into essential amino acids, L-leucine, L-valine, and L-isoleucine using artificial cells containing an immobilized multienzyme system and dextran-NAD. L-lactic dehydrogenase for coenzyme recycling.
abstract: A multienzyme system consisting of leucine dehydrogenase (EC 1.4.1.9), L-lactic dehydrogenase (EC 1.1.1.27), urease (EC 3.5.1.5), and dextran-NAD+ was microencapsulated within artificial cells. This system could convert ammonia and urea into essential amino acids, L-leucine, L-valine, and L-isoleucine. L-lactate acted as a cosubstrate for the regeneration of dextran-NADH. Greater concentrations of L-lactate favored the higher conversion ratios. The effects of ammonium salts and urea on reaction rate were also studied. The relative reaction rates in ammonium salts solutions were 44.6-78.8% of those in urea solutions. More than 90% of the original activity was retained when artificial cells were kept at 4 degrees C for 6 wk.
authors.affiliation: Artificial Cells and Organs Research Centre, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.
authors.forename: K F
authors.initials: KF
authors.lastname: Gu
authors.forename: T M
authors.initials: TM
authors.lastname: Chang
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000378:metabolism; D000601:Amino Acids, Essential / Q000378:metabolism*; D000641:Ammonia / Q000378:metabolism*; D003067:Coenzymes / Q000378:metabolism; D003911:Dextrans; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000378:metabolism*; D007532:Isoleucine / Q000378:metabolism; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D007930:Leucine / Q000378:metabolism; D050803:Leucine Dehydrogenase; D009243:NAD; D014508:Urea / Q000378:metabolism*; D014510:Urease / Q000378:metabolism; D014633:Valine / Q000378:metabolism
chemical_list: D000601:Amino Acids, Essential; D003067:Coenzymes; D003911:Dextrans; D004800:Enzymes, Immobilized; D007773:Lactates; C068634:dextran-NAD; D007532:Isoleucine; D009243:NAD; D019344:Lactic Acid; D000641:Ammonia; D014508:Urea; D007770:L-Lactate Dehydrogenase; D000594:Amino Acid Oxidoreductases; D050803:Leucine Dehydrogenase; D014510:Urease; D007930:Leucine; D014633:Valine