title: Structure and function of D-amino acid oxidase.  IX. Changes in the fluorescence polarization of FAD upon complex formation.
abstract: 1. The fluorescence polarization, P, of FAD increased on complex formation with the apoenzyme of D-amino acid oxidase [D-amino acid: O2 ocidoreductase (deaminating), EC 1.4.3.3].  The time course of the increase was monophasic.  The values of P were extimated to be 0.04, 0.4, and 0.4 for FAD, the enzyme and the enzyme-benzoate complex, respectively.  2. The value of P of the enzyme is dependent on its concentration, indicating that the degrees of dissociation of FAD in the monomer and dimer are different.  The dissociation constant was calculated to be 7 times 10-minus 7 M for the monomeric form of the enzyme.  This value is far larger than the value for the dimeric form of the enzyme, 1 times 10-minus 8 M, calculated from equilibrium dialysis data.  3. Changes in fluorescence polarization of the enzyme due to changes in solution pH or temperature can be explained in terms of the monomer-dimer equilibrium.
mesh_terms: D000818:Animals; D001051:Apoenzymes; D001665:Binding Sites; D003605:D-Amino-Acid Oxidase / Q000378:metabolism; D005182:Flavin-Adenine Dinucleotide; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000201:enzymology; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D011485:Protein Binding; D013050:Spectrometry, Fluorescence; D013552:Swine; D013696:Temperature; D013997:Time Factors
chemical_list: D001051:Apoenzymes; D046911:Macromolecular Substances; D005182:Flavin-Adenine Dinucleotide; D003605:D-Amino-Acid Oxidase