Laboratory of Food Chemistry, Wageningen University & Research, Bornse Weilanden 9, 6708 WG, Wageningen (The, Netherlands.
Biocatalysis and Biosensing Laboratory, Department of Food Science and Technology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190, Vienna, Austria.
ChemSusChem. 2022 Jan 21;15(2):e202102203. doi: 10.1002/cssc.202102203. Epub 2021 Dec 18.
Lytic polysaccharide monooxygenases (LPMOs) play a key role in enzymatic degradation of hard-to-convert polysaccharides, such as chitin and cellulose. It is widely accepted that LPMOs catalyze a single regioselective oxidation of the C1 or C4 carbon of a glycosidic linkage, after which the destabilized linkage breaks. Here, a series of novel C4/C6 double oxidized cello-oligosaccharides was discovered. Products were characterized, aided by sodium borodeuteride reduction and hydrophilic interaction chromatography coupled to mass spectrometric analysis. The C4/C6 double oxidized products were generated by C4 and C1/C4 oxidizing LPMOs, but not by C1 oxidizing ones. By performing incubation and reduction in H O, it was confirmed that the C6 gem-diol structure resulted from oxygenation, although oxidation to a C6 aldehyde, followed by hydration to the C6 gem-diol, could not be excluded. These findings can be extended to how the reactive LPMO-cosubstrate complex is positioned towards the substrate.
溶细胞单加氧酶（LPMOs）在酶解难转化多糖（如几丁质和纤维素）方面发挥着关键作用。人们普遍认为，LPMOs 催化糖苷键的 C1 或 C4 碳的单一区域选择性氧化，之后不稳定的键断裂。在这里，发现了一系列新型 C4/C6 双氧化的纤维寡糖。通过使用硼氢化钠还原和亲水相互作用色谱法与质谱分析相结合，对产物进行了表征。C4/C6 双氧化产物是由 C4 和 C1/C4 氧化 LPMOs 产生的，但不是由 C1 氧化 LPMOs 产生的。通过在 H O 中进行孵育和还原，可以确认 C6 偕二醇结构是由氧化产生的，尽管不能排除 C6 醛氧化，然后水化成 C6 偕二醇的情况。这些发现可以扩展到活性 LPMO-共底物复合物如何定位在底物上。
