Oxalate oxidase composition for assay of oxalate

A process for the preparation of an oxalate oxidase composition having an activity of at least about 5 international enzyme units/mg. of protein at 37.degree. C. in said composition, said composition comprising an oxalate oxidase having an optimum pH of about 5.7, having an oxidase activity on citrate of only about 2% of its oxidase activity on oxalate, having substantially no oxidase activity on L-ascorbate, glyoxylate, glycolate, .beta.-hydroxypyrovate, 2-ketoglutarate or succinate and not being inhibited by 1.0 mM sodium chloride solution which process comprises the following steps:

• (a) finely dividing beet stems in an aqueous solution substantially isotonic with the cells of said stems;
• (b) filtering the solution produced in step (a) through a coarse filter;
• (c) centrifuging the filtrate produced in step (b) until a precipitate forms;
• (d) suspending the precipitate formed in step (c) in an aqueous sugar solution;
• (e) adding a water-miscible organic solvent to the suspension formed in step (d), thereby causing precipitation of an oxalate-oxidase-containing precipitate;
• (f) dissolving the precipitate formed in step (e) in an aqueous solution containing taurodeoxycholic acid;
• (g) dialyzing the solution formed in step (f) against a buffer solution having a pH of about 5.7 to about 6.8;
• and
• (h) chromatographing the dialyzed solution from step (g) by solid/liquid chromatography using a buffer of pH about 5.7 as the liquid phase.