Riegert U, Heiss G, Fischer P, Stolz A
Institut für Mikrobiologie, Universität Stuttgart, 70569 Stuttgart, Germany.
J Bacteriol. 1998 Jun;180(11):2849-53. doi: 10.1128/JB.180.11.2849-2853.1998.
A 2,3-dihydroxybiphenyl 1,2-dioxygenase from the naphthalenesulfonate-degrading bacterium Sphingomonas sp. strain BN6 oxidized 3-chlorocatechol to a yellow product with a strongly pH-dependent absorption maximum at 378 nm. A titration curve suggested (de)protonation of an ionizable group with a pKa of 4.4. The product was isolated, purified, and converted, by treatment with diazomethane, to a dimethyl derivative and, by incubation with ammonium chloride, to a picolinic acid derivative. Mass spectra and 1H and 13C nuclear magnetic resonance (NMR) data for these two derivatives prove a 3-chloro-2-hydroxymuconic semialdehyde structure for the metabolite, resulting from distal (1,6) cleavage of 3-chlorocatechol. 3-Methylcatechol and 2,3-dihydroxybiphenyl are oxidized by this enzyme, in contrast, via proximal (2,3) cleavage.
来自萘磺酸盐降解细菌鞘氨醇单胞菌属菌株BN6的2,3-二羟基联苯1,2-双加氧酶将3-氯儿茶酚氧化为一种黄色产物，该产物在378 nm处有强烈的pH依赖性吸收最大值。滴定曲线表明存在一个pKa为4.4的可电离基团的（去）质子化。该产物经分离、纯化后，用重氮甲烷处理转化为二甲基衍生物，与氯化铵孵育转化为吡啶甲酸衍生物。这两种衍生物的质谱以及1H和13C核磁共振（NMR）数据证明该代谢产物为3-氯-2-羟基粘康酸半醛结构，是由3-氯儿茶酚的远端（1,6）裂解产生的。相比之下，3-甲基儿茶酚和2,3-二羟基联苯经该酶氧化是通过近端（2,3）裂解。
