Abstract
Paper partition chromatography or paper ionophoresis is hardly applied to determination of a small quantity of FAD in a sample containing large amounts of other flavin derivatives. In such a case, an enzymatic method using D-amino acid oxidase is preferable, so studies were made on this method and following results were obtained. In order to obtain the apo-enzyme which indicated no oxygen uptake without adding FAD, it was necessary to repeat three times the acidification procedure by the method of Warburg. Under the conditions which the author employed, addition of Cu^<++> inhibited the enzyme action. However, other divalent cations such as Zn^<++>, Ni^<++>, Mn^<++>, Mg^<++>, Fe^<++> and Fe^<+++> had no effect. AMP and ATP inhibited the enzyme action, while adenine and adenosine exerted no effect.
