Structure and Function of D-Amino Acid Oxidase
IX. Changes in the Fluorescence Polarization of FAD upon Complex Formation
1975 年 77 巻 2 号 p. 463-468
詳細
1975 年 77 巻 2 号 p. 463-468
1. The fluorescence polarization, P, of FAD increased on complex formation with the apoenzyme of D-amino acid oxidase [D-amino acid: O2 oxidoreductase (deaminat-ing), EC 1.4.3.3]. The time course of the increase was monophasic. The values of P were estimated 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 7×10-7M for the monomeric form of the enzyme. This value is far larger than the value for the dimeric form of the enzyme, 1×10-8M, calculated from equilibrium dialysis data.
3. Changes in the fluorescence polarization of the enzyme due to changes in solution pH or temperature can be explained in terms of the monomer-dimer equilibrium.
