A NOVEL ANTHRAQUINONE RING CLEAVAGE ENZYME FROM ASPERGILLUS-TERREUS
A NOVEL ANTHRAQUINONE RING CLEAVAGE ENZYME FROM ASPERGILLUS-TERREUS
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DOI：
10.1093/oxfordjournals.jbchem.a122365
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发表时间：
1988-05-01
影响因子：
2.7
通讯作者：
SANKAWA, U
中科院分区：
文献类型：
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作者：
FUJII, I;EBIZUKA, Y;SANKAWA, U
在土曲霉（+）-geodin生产者的无细胞提取物中发现了一种催化蒽醌questin环断裂形成二苯甲酮去甲基磺氯素的酶活性。通过高分辨质谱和化学载体稀释分析，确定产物为去甲基磺氯菊酯。该酶显示出对NADPH和分子氧的绝对需求。因此，被命名为questin加氧酶的酶被认为是单加氧酶。最适pH为7.5左右。该酶非常不稳定，在4 ℃下储存过夜后完全失去活性。0.05M磷酸盐缓冲液，pH 7.5。通过向缓冲液中加入多元醇和非离子洗涤剂吐温80，部分克服了questin加氧酶的不稳定性。经DEAE-cellulose柱层析，得到两个蛋白组分DE-I和DE-II。这两种馏分都不与questin本身反应。然而，DE-I和DE-II的组合重构了questin加氧酶系统以将questin转化为去甲基磺氯灵。这一结果表明，该系统不是一个简单的加氧酶和水解酶的组合，但需要一些额外的因素，如电子转移蛋白。
An enzyme activity which catalyzes the ring cleavage of the anthraquinone questin to form benzophenone desmethylsulochrin was found in the cell-free extract of Aspergillus terreus, a (+)-geodin producer. The product was identified as desmethylsulochrin by high-resolution mass spectroscopy and chemical carrier dilution analysis. The enzyme showed an absolute requirement of NADPH and molecular oxygen. Therefore, the enzyme, named questin oxygenase, was considered to be classified as a monooxygenase. The optimum pH was around 7.5. The enzyme was very unstable and lost its activity completely after storage overnight at 4.degree. C in 0.05M phosphate buffer, pH 7.5. The instability of the questin oxygenase was partially overcome by the addition of polyols and the non-ionic detergent Tween 80 to the buffer. By DEAE-cellulose column chromatography, two protein fractions named DE-I and DE-II, were obtained. Neither fraction reacted with questin by itself. However, the combination of DE-I and DE-II reconstituted the questin oxygenase system to convert questin to desmethylsulochrin. This result suggested that the system is not a simple combination of oxygenase and hydrolase, but requires some additional factor(s) such as electron transfer protein.