Biotechnology of Natural Products, School of Life Sciences, Technical University of Munich, Liesel-Beckmann-Str. 1, 85354 Freising, Germany.
4GENE, Lise-Meitner-Straße 30, 85354 Freising, Germany.
Molecules. 2021 Sep 10;26(18):5511. doi: 10.3390/molecules26185511.
Menthol is a cyclic monoterpene alcohol of the essential oils of plants of the genus , which is in demand by various industries due to its diverse sensorial and physiological properties. However, its poor water solubility and its toxic effect limit possible applications. Glycosylation offers a solution as the binding of a sugar residue to small molecules increases their water solubility and stability, renders aroma components odorless and modifies bioactivity. In order to identify plant enzymes that catalyze this reaction, a glycosyltransferase library containing 57 uridine diphosphate sugar-dependent enzymes (UGTs) was screened with (±)-menthol. The identity of the products was confirmed by mass spectrometry and nuclear magnetic resonance spectroscopy. Five enzymes were able to form (±)-menthyl-β-d-glucopyranoside in whole-cell biotransformations: UGT93Y1, UGT93Y2, UGT85K11, UGT72B27 and UGT73B24. In vitro enzyme activity assays revealed highest catalytic activity for UGT93Y1 (7.6 nkat/mg) from towards menthol and its isomeric forms. Although UGT93Y2 shares 70% sequence identity with UGT93Y1, it was less efficient. Of the five enzymes, UGT93Y1 stood out because of its high in vivo and in vitro biotransformation rate. The identification of novel menthol glycosyltransferases from the tea plant opens new perspectives for the biotechnological production of menthyl glucoside.
薄荷醇是薄荷属植物精油中的一种环状单萜醇，由于其具有多种感官和生理特性，因此受到各行业的需求。然而，其较差的水溶性和毒性限制了其可能的应用。糖基化提供了一种解决方案，因为小分子与糖残基的结合增加了它们的水溶性和稳定性，使香气成分无味，并改变了生物活性。为了鉴定催化该反应的植物酶，用（±）-薄荷醇筛选了包含 57 种尿苷二磷酸糖依赖性酶（UGTs）的糖基转移酶文库。通过质谱和核磁共振波谱法确认了产物的身份。有 5 种酶能够在全细胞生物转化中形成（±）-薄荷基-β-D-吡喃葡萄糖苷：UGT93Y1、UGT93Y2、UGT85K11、UGT72B27 和 UGT73B24。体外酶活性测定显示，来自 的 UGT93Y1（7.6 nkat/mg）对薄荷醇及其同分异构体的催化活性最高。尽管 UGT93Y2 与 UGT93Y1 具有 70%的序列同一性，但它的效率较低。在这 5 种酶中，UGT93Y1 因其高体内和体外生物转化速率而脱颖而出。从茶树中鉴定出新型薄荷醇糖基转移酶，为生物技术生产薄荷基葡萄糖苷开辟了新的前景。
