SummaryIn this study, an α‐galactosidase (MPG) was produced by submerged fermentation from Monascus purpureus, a food‐grade fungus used for making red yeast rice. MPG was purified from intracellular extract which showed a subunit molecular mass of 95 kDa. MPG was optimally active at pH 4.0 and 50 °C and was stable between pH 3.5–8.0 and at temperatures up to 50 °C. The enzyme retained its activity in the presence of most of the metal ions except Cu2+ and Fe2+. MPG exhibited remarkable resistance to the proteases, pepsin, trypsin and proteinase K as well as to the sugars, galactose and sucrose. Moreover, it retained complete activity under simulated gastric conditions. The enzyme displayed specificity for the substrates, melibiose, raffinose and stachyose and was able to hydrolyze these oligosaccharides. It was effective in the removal of non‐digestible raffinose family oligosaccharides (RFOs) from soybeans, chickpeas and kidney beans. MPG was immobilised onto chitosan and the immobilised enzyme (iMPG) displayed higher optimal temperature (60 °C), better thermostability and substrate specificity as compared to MPG. iMPG was also capable of hydrolyzing RFOs in chickpeas and could be efficiently reused six times. In view of their superior properties, MPG and iMPG may have great prospects in the food and feed industries for the removal of RFOs from soy and other legumes.

中文翻译：

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紫红曲霉中蛋白酶抗性α-半乳糖苷酶的纯化、表征和固定化及其在去除棉子糖家族寡糖中的应用

摘要在本研究中，通过深层发酵从 α-半乳糖苷酶（MPG）中提取紫红曲霉，一种用于制作红曲米的食品级真菌。 MPG 从细胞内提取物中纯化，其亚基分子量为 95 kDa。 MPG 在 pH 4.0 和 50 °C 时具有最佳活性，并且在 pH 3.5-8.0 和高达 50 °C 的温度下保持稳定。该酶在除 Cu 之外的大多数金属离子存在下仍保持其活性2+和铁2+。 MPG 对蛋白酶、胃蛋白酶、胰蛋白酶和蛋白酶 K 以及糖、半乳糖和蔗糖表现出显着的抗性。此外，它在模拟胃条件下保留了完整的活性。该酶对底物蜜二糖、棉子糖和水苏糖表现出特异性，并且能够水解这些寡糖。它可以有效去除大豆、鹰嘴豆和芸豆中不可消化的棉子糖家族寡糖 (RFO)。将MPG固定在壳聚糖上，与MPG相比，固定化酶（iMPG）表现出更高的最适温度（60℃）、更好的热稳定性和底物特异性。 iMPG 还能够水解鹰嘴豆中的 RFO，并且可以有效地重复使用六次。鉴于其优越的性能，MPG 和 iMPG 在食品和饲料工业中用于去除大豆和其他豆类中的 RFO 可能具有广阔的前景。