title: Immobilization and characterization of D-amino acid oxidase.
abstract: Optimal conditions with respect to pH, concentration of glutaraldehyde and enzyme, and order of addition of enzyme and crosslinking reagent were established for the immobilization of hog kidney D-amino acid oxidase to an attapulgite support. Yields of 40 to 70% were generally attained although when low concentrations of enzyme were used yields were consistently greater than 100%. It is suggested that this is due to a dimer leads to monomer shift at low protein concentrations. The stability of soluble D-amino acid oxidase was dependent on the buffer in which it was stored (pyrophosphate-phosphate greater than borate greater than Tris). Stability of immobilized enzyme was less than soluble in pyrophosphate-phosphate buffer, but storage in the presence of FAD improved stability. In addition, treatment of stored, immobilized enzyme with FAD before assay restored some of its activity. The immobilized D-amino acid oxidase was less stable to heat (50 degrees C) than the soluble enzyme from pH 6 to 8 but was more stable above and below these values. Apparent Km values for D-alanine, D-valine, and D-tryptophan decreased for the immobilized enzyme compared to the soluble.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D002627:Chemistry, Physical; D003605:D-Amino-Acid Oxidase / Q000378:metabolism; D004789:Enzyme Activation; D004800:Enzymes, Immobilized / Q000378:metabolism; D005976:Glutaral; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D013997:Time Factors
chemical_list: D004800:Enzymes, Immobilized; D003605:D-Amino-Acid Oxidase; D005976:Glutaral