[218a] Assay of amino acid oxidase

This chapter discusses assay of amino acid oxidase. Conditions are given in the chapter for the determination of the L-amino acid oxidase of snake venoms and the D-amino acid oxidase of mammalian kidney and liver. Although the principles are the same for both, experimental details differ because of differences in the stability, pH optimum, and other properties of the two types of enzyme. For example, FAD must be added in the D-amino acid oxidase assay, because it dissociates readily from the enzyme, whereas in the case of L-amino acid oxidase the prosthetic group is so tightly bound that the addition of free FAD in the assay mixture is unnecessary. The spectrophotometric assay described in chapter is useful over a wide range of enzyme concentrations and is convenient as a general procedure, for example, for following enzyme purification, assaying fractions from a column, or observing changes in activity resulting from enzyme modifications.