The action of o-dihydric phenols in the hydroxylation of p-coumaric acid by a phenolase from leaves of spinach beet (Beta vulgaris L.).
The action of o-dihydric phenols in the hydroxylation of p-coumaric acid by a phenolase from leaves of spinach beet (Beta vulgaris L.).
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菠菜甜菜 (Beta vulgaris L.) 叶中酚酶对邻香豆酸羟基化过程中邻二元酚的作用。
DOI：
10.1042/bj1190089
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发表时间：
1970
影响因子：
4.1
通讯作者：
V. S. Butt
中科院分区：
文献类型：
--
作者：
P. Vaughan;V. S. Butt
1.在一定条件下，研究了菠菜甜菜（Beta vulgaris L.）只有在一个滞后期后才能观察到其最大速率。2.通过降低反应速率与较低的酶浓度或通过增加它与较高浓度的还原剂，滞后期的长度呈负相关的最大速率随后开发。3.低浓度的咖啡酸或其他邻二羟基酚废除了这一滞后期。与咖啡酸，羟基化率是独立的还原剂。4.羟化抑制二乙基二硫代氨基甲酸酯，但低浓度的抑制剂羟基化后恢复滞后期。通过加入高浓度的咖啡酸或其他邻二羟基酚，可以再次消除这种滞后。5.儿茶酚氧化酶活性没有表现出滞后期，并没有恢复从二乙基二硫代氨基甲酸酯抑制。6.纯化的酶含有0.17-0.33%的铜;具有最高比活性的制剂被发现具有最高的铜含量。7.结果被解释为表明，邻-二元酚的氧化将酶铜转化成一种在羟基化中具有催化活性的物种。这可能代表了酚酶复合物的儿茶酚氧化酶活性的主要功能。电子给体主要但不完全参与该反应中生成的邻醌的还原。
1. Under defined conditions, the hydroxylation of p-coumaric acid catalysed by a phenolase from leaves of spinach beet (Beta vulgaris L.) was observed to develop its maximum rate only after a lag period. 2. By decreasing the reaction rate with lower enzyme concentrations or by increasing it with higher concentrations of reductants, the length of the lag period was inversely related to the maximum rate subsequently developed. 3. Low concentrations of caffeic acid or other o-dihydric phenols abolished this lag period. With caffeic acid, the rate of hydroxylation was independent of the reductant employed. 4. Hydroxylation was inhibited by diethyldithiocarbamate, but with low inhibitor concentrations hydroxylation recovered after a lag period. This lag could again be abolished by the addition of high concentrations of caffeic acid or other o-dihydric phenols. 5. Catechol oxidase activity showed no lag period, and did not recover from diethyldithiocarbamate inhibition. 6. The purified enzyme contained 0.17-0.33% copper; preparations with the highest specific activity were found to have the highest copper content. 7. The results are interpreted to suggest that the oxidation of o-dihydric phenols converts the enzymic copper into a species catalytically active in hydroxylation. This may represent the primary function for the catechol oxidase activity of the phenolase complex. The electron donors are concerned mainly, but not entirely, in the reduction of o-quinones produced in this reaction.