Pascal R A, Huang D S
Arch Biochem Biophys. 1986 Jul;248(1):130-7. doi: 10.1016/0003-9861(86)90409-1.
The reactions of 3-ethylcatechol and 3-(methylthio)catechol with catechol 1,2-dioxygenase and catechol 2,3-dioxygenase from Pseudomonas putida were examined. Both 3-substituted catechols are oxidized by catechol 2,3-dioxygenase at approximately 30% of the rate observed for catechol oxidation by this enzyme. Analysis of the products of the reactions showed that ring cleavage occurs in a normal fashion between carbons 2 and 3 of the alternate substrates. 3-Ethylcatechol is oxidized by catechol 1,2-dioxygenase at about 6% of the rate of catechol oxidation; ring cleavage occurs between carbons 1 and 2 to give 2-ethyl-cis,cis-muconic acid. However, 3-(methylthio)catechol is a very poor substrate for catechol 1,2-dioxygenase (0.8% of the rate of catechol), but it is a potent competitive inhibitor (Ki = 0.6 microM). The effects of 3-(methylthio)catechol and 3-ethylcatechol on the visible and EPR spectra of catechol 1,2-dioxygenase are also reported.
研究了3-乙基儿茶酚和3-(甲硫基)儿茶酚与恶臭假单胞菌的儿茶酚1,2-双加氧酶和儿茶酚2,3-双加氧酶的反应。两种3-取代儿茶酚均被儿茶酚2,3-双加氧酶氧化，其氧化速率约为该酶氧化儿茶酚速率的30%。对反应产物的分析表明，在替代底物的碳2和碳3之间以正常方式发生环裂解。3-乙基儿茶酚被儿茶酚1,2-双加氧酶氧化的速率约为儿茶酚氧化速率的6%；在碳1和碳2之间发生环裂解，生成2-乙基-顺,顺-粘康酸。然而，3-(甲硫基)儿茶酚是儿茶酚1,2-双加氧酶的一种非常差的底物(为儿茶酚速率的0.8%)，但它是一种有效的竞争性抑制剂(Ki = 0.6 microM)。还报道了3-(甲硫基)儿茶酚和3-乙基儿茶酚对儿茶酚1,2-双加氧酶可见光谱和电子顺磁共振光谱的影响。
