Due to the increasing demand for natural food ingredients, including taste-active compounds, enzyme-catalyzed conversions of natural substrates, such as flavonoids, are promising tools to align with the principles of Green Chemistry. In this study, a novel O-methyltransferase activity was identified in the mycelium of Lentinula edodes, which was successfully applied to generate the taste-active flavonoids hesperetin, hesperetin dihydrochalcone, homoeriodictyol, and homoeriodictyol dihydrochalcone. Furthermore, the mycelium-mediated OMT activity allowed for the conversion of various catecholic substrates, yielding their respective (iso-)vanilloids, while monohydroxylated compounds were not converted. By means of a bottom-up proteomics approach, three putative O-methyltransferases were identified, and subsequently, synthetic, codon-optimized genes were heterologously expressed in Escherichia coli. The purified enzymes confirmed the biocatalytic O-methylation activity against targeted flavonoids containing catechol motifs.

中文翻译：

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香菇中的新型儿茶酚 O-甲基转移酶催化呈味活性黄酮类化合物的生成

由于对天然食品成分（包括味觉活性化合物）的需求不断增加，天然底物（例如类黄酮）的酶催化转化是符合绿色化学原理的有前途的工具。在本研究中，在香菇菌丝体中鉴定出一种新的O-甲基转移酶活性，该活性被成功应用于生成具有味觉活性的类黄酮橙皮素、橙皮素二氢查尔酮、高圣草酚和高圣草酚二氢查尔酮。此外，菌丝体介导的OMT活性允许各种儿茶酚底物的转化，产生它们各自的(异)香草素，而单羟基化化合物没有被转化。通过自下而上的蛋白质组学方法，鉴定了三种假定的O-甲基转移酶，随后，合成的密码子优化基因在大肠杆菌中异源表达。纯化的酶证实了针对含有儿茶酚基序的目标黄酮类化合物的生物催化O-甲基化活性。