School of Food and Biological Engineering, Jiangsu University, Zhenjiang, 212013, China.
Department of Pharmacy, University of Naples Federico II, Naples, 80131, Italy.
Food Funct. 2024 May 20;15(10):5439-5449. doi: 10.1039/d3fo04616h.
Barley, rich in bioactive components including dietary fiber, polyphenolic compounds and functional proteins, exhibits health benefits such as regulating glucose and lipid metabolism. Previous studies have found that the content and composition of free phenolic acids in barley may be significantly changed by fermentation with the laboratory patented strain dy-1 ( dy-1), but the mechanism of enzymatic release of phenolic acid remains to be elucidated. Based on this, this study aimed to identify the key enzyme in dy-1 responsible for releasing the bound phenolic acid and to further analyze its enzymatic properties. The Carbohydrate-Active enZYmes database revealed that dy-1 encodes 7 types of auxiliary enzymes, among which we have identified a membrane sulfatase. The enzyme gene was heterologous to that expressed in , and a recombinant strain was induced to produce the target protein and purified. The molecular weight of the purified enzyme was about 59.9 kDa, with 578.21 U mg enzyme activity. The optimal temperature and pH for LPMS05445 expression were 40 °C and 7.0, respectively. Furthermore, enzymatic hydrolysis by LPMS05445 can obviously change the surface microstructure of dietary fiber from barley bran and enhance the release of bound phenolic acid, thereby increasing the free phenolic acid content and improving its physiological function. In conclusion, sulfatase produced by dy-1 plays a key role in releasing bound phenolic acids during the fermentation of barley.
大麦富含膳食纤维、多酚化合物和功能性蛋白质等生物活性成分，具有调节糖脂代谢等健康益处。先前的研究发现，实验室专利菌株 dy-1 发酵可能会显著改变大麦中游离酚酸的含量和组成，但酚酸酶解释放的机制仍需阐明。基于此，本研究旨在鉴定出 dy-1 中负责释放结合态酚酸的关键酶，并进一步分析其酶学性质。碳水化合物活性酶数据库显示，dy-1 编码 7 种辅助酶，其中我们鉴定出一种膜硫酸酯酶。该酶基因在 中异源表达，并诱导重组菌产生目标蛋白并进行纯化。纯化酶的分子量约为 59.9 kDa，酶活为 578.21 U mg。LPMS05445 表达的最适温度和 pH 值分别为 40°C 和 7.0。此外，LPMS05445 的酶解作用可以明显改变大麦麸皮膳食纤维的表面微观结构，促进结合态酚酸的释放，从而提高游离酚酸含量，改善其生理功能。综上所述，dy-1 产生的硫酸酯酶在大麦发酵过程中对释放结合态酚酸起着关键作用。
