Crystallization of the Complex of D-Amino-Acid Oxidase and ‘Substrate-Substitute’

Abstract

IN an earlier communication¹, it was reported that a crystal was obtained from the mixture of D-amino-acid oxidase apo-protein, flavin-adenine-dinucleotide and benzoate, a ‘substrate-substitute’. It was also found that the crystal is composed of equimoles of the apo-protein, coenzyme and benzoate. By adding D-alanine to the solution of the crystal, the complete decolorization of the coenzyme accompanied by the liberation of the benzoate was observed. This result indicated that the benzoate can be replaced by the substrate, and that the enzyme is not denatured when crystallized by combining with benzoate. In the present experiment, we sought to find another ‘substrate-substitute’ to crystallize this enzyme.