Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, Jiangsu, China.
Appl Biochem Biotechnol. 2013 Aug;170(8):2021-33. doi: 10.1007/s12010-013-0350-8. Epub 2013 Jun 28.
The increased additive amount of adjuncts in the raw materials of Chinese beer requires the usage of protease to release more water-soluble proteins. Here, a metallo-neutral protease suited for brewing industry was purified from Bacillus amyloliquefaciens SYB-001. A 5.6-fold purification of the neutral protease was achieved with a 4-step procedure including ammonium sulfate precipitation, ion-exchange, hydrophobic interaction, and gel-filtration chromatography. The molecular mass of the enzyme was estimated to be 36.8 kDa. The protease was active and stable at a wide range of pH from 6.0-10.0 with an optimum at pH 7.0. The highest activity of the purified enzyme was found at 50 °C. The existence of manganese ion would specifically enhance the protease activity. Comparing with other commercial neutral proteases in China, adding the new neutral protease during mashing process would release more amino acids from wort such as aspartic acid, arginine, methione, and histidine, resulting in a better amino acid profile in wort. Moreover, the wort processed with the new neutral protease had a higher α-amino nitrogen concentration, which would ensure a vigorous yeast growth and better flavor. The study of the enzyme could lay a foundation for its industrial application and further research.
中国啤酒原料中添加的辅料量增加，需要使用蛋白酶释放更多的水溶性蛋白质。在这里，从解淀粉芽孢杆菌 SYB-001 中纯化出一种适用于酿造工业的金属中性蛋白酶。通过包括硫酸铵沉淀、离子交换、疏水相互作用和凝胶过滤层析在内的 4 步程序，实现了中性蛋白酶的 5.6 倍纯化。该酶的分子量估计为 36.8 kDa。该蛋白酶在 pH 6.0-10.0 的较宽范围内具有活性和稳定性，最适 pH 为 7.0。纯化酶的最高活性在 50°C 时发现。锰离子的存在会特异性地增强蛋白酶的活性。与中国其他商业中性蛋白酶相比，在糖化过程中添加新型中性蛋白酶会从麦汁中释放出更多的氨基酸，如天冬氨酸、精氨酸、甲硫氨酸和组氨酸，从而使麦汁中的氨基酸组成更好。此外，用新型中性蛋白酶处理的麦汁具有更高的α-氨基氮浓度，这将确保酵母的旺盛生长和更好的风味。该酶的研究为其工业应用和进一步研究奠定了基础。
