[Isolation and characterisation of L-ascorbic acid oxidase (EC 1.10.3.3) from wheat flour (author's transl)].

Wheat flour (Caribo, 0.55% ash) is extracted with 0.4 M-NaCl-solution, the L-ascorbic acid oxidase precipitated with (NH4)2SO4 and this concentrate separated by thinlayer isoelectric focussing on polyacrylamid- and dextrangel. 8-12 active fractions (isoenzymes) are detected with a high specifity for L-ascorbic acid in respect in L-isoascorbic acid activity). The molecular weights are 165,000-175,000 (determined by dextran gel-thin layer chromatography). In fresh flour the activity is near 28 mg L-ascorbic acid per kg flour in 30 min, after 30 days the activity has diminished to 5% after 60 days no activity is detectable.