Stabilization of lignin peroxidases in white rot fungi by tryptophan
Stabilization of lignin peroxidases in white rot fungi by tryptophan
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DOI：
10.1128/aem.63.7.2543-2548.1997
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发表时间：
1997-07-01
影响因子：
4.4
通讯作者：
Dobson, ADW
中科院分区：
文献类型：
--
作者：
Collins, PJ;Field, JA;Dobson, ADW
补充色氨酸的各种文化的白色腐真菌被发现有一个大的刺激作用的木质素过氧化物酶的活性水平。这种增强大于在木质素过氧化物酶再循环剂藜芦醇存在下观察到的增强。利用逆转录-PCR，我们发现，色氨酸不起作用，诱导木质素过氧化物酶的基因转录水平的表达。相反，观察到的活性增强可能是由于色氨酸对H2 O2失活的保护作用。在使用部分纯化的木质素过氧化物酶制剂的实验中，确定色氨酸及其衍生物吲哚的作用方式与藜芦醇相同，将化合物II（木质素过氧化物酶的氧化形式）转化为铁酶，从而完成催化循环。此外，色氨酸被发现是一个更好的底物木质素过氧化物酶比藜芦醇。色氨酸或吲哚的加入增强了偶氮染料甲基橙子和铬蓝黑的氧化。藜芦醇对偶氮染料氧化的刺激作用以前已被证明是由于其酶循环功能。我们的数据使我们能够提出，色氨酸稳定木质素过氧化物酶作为还原剂的酶。
Supplementation of various cultures of white rot fungi with tryptophan was found to have a large stimulatory effect on lignin peroxidase activity levels. This enhancement was greater than that observed in the presence of the lignin peroxidase recycling agent veratryl alcohol. Using reverse transcription-PCR, we found that tryptophan does not act to induce lignin peroxidase expression at the level of gene transcription. Instead, the activity enhancement observed is likely to result from the protective effect of tryptophan against H2O2 inactivation. In experiments using a partially purified lignin peroxidase preparation, tryptophan and its derivative indole were determined to function in the same way as veratryl alcohol in converting compound II, an oxidized form of Lignin peroxidase, to ferric enzyme, thereby completing the catalytic cycle. Furthermore, tryptophan was found to be a better substrate for lignin peroxidase than veratryl alcohol. Inclusion of either tryptophan or indole enhanced the oxidation of the azo dyes methyl orange and Eriochrome blue black. Stimulation of azo dye oxidations by veratryl alcohol has previously been shown to be due to its enzyme recycling function. Our data allow us to propose that tryptophan stabilizes lignin peroxidase by acting as a reductant for the enzyme.