β-アミラーゼのアスコルビン酸に依る阻害に関する研究 : (第4報) H2O2の影響

概要

論文の詳細を見る
1. In order to elucidate the mechanism of the inhibition of sweet potato β-amylase by ascorbic acid, inactivation of β-amylase by H2O2 and the effect of H2O2, on the inhibition by ascorbic acid were examined. (Fig. 1_??_Fig. 3) 2. From the results shown in figures 1 to 3 and those previously reported, the most probable mechanism of the inhibition of β-amylase by ascorbic acid plus Cu++ was proposed as follows. First step. Essential-SH groups of enzyme combined rapidly with Cu+ formed by ascorbic acid. Second step. As ascorbic acid decreases, cuprous mercaptides returnd partly to free -SH groups and thus the enzyme restorgd its activity, butanother (aetivateded) parts of mercaptides underwent an intramolecular rearrangement by atmospheric O2 to become inactive disulfide form. In this oxidation reaction, H2O2, accumulated during the course of autoxidatiof of ascor-bic acid might serve in the same way as O2. The change in this step was an “induced oxidation”, sinceno appreciable inactivation occured by Cu++ alone, and the mechanism might have some analogy to that of the autoxidaiton of cysteine in the presence of Fe++ in MICHAELIS theory. Third step. From relatively later stage of autoxidation of ascorbic acid, the remaining -SH groups are oxidised directly to disulfide form by H2O2 accumulated. 3. The feeble inactivation by ascorbic acid alone (Curve 1 in Fig. 2) can only be understood as the change in the second step of the above mechanism.
社団法人日本農芸化学会の論文

β-アミラーゼのアスコルビン酸に依る阻害に関する研究 : (第4報) H2O2の影響

スポンサーリンク

概要

著者

関連論文

スポンサーリンク