摘　要：为了提高凝结芽孢杆菌（Bacillus coagulans）X3角蛋白酶的水解效率，对其粗酶液的酶学性质及降解羽毛角蛋白的效果进行了研究。结果表明，粗酶液的最适反应温度为60℃，最适pH为7.0～8.0，在70～80℃时具有较好的热稳定性。金属离子中Ca2+、Mn2+对角蛋白酶活性起促进作用，Cu2+、Ni2+强烈抑制角蛋白酶活性，而Na+、Mg2+、Fe3+对酶活性无显著影响。化学试剂苯甲基磺酰氟（PMSF）、乙二胺四乙酸（EDTA）对酶活性有较强的抑制作用，β-巯基乙醇和二硫基苏糖醇（DTT）可显著提高酶活性，十二烷基磺酸钠（SDS）和二甲基亚砜（DMSO）对酶活性没有显著影响。优化条件下降解羽毛，产物中游离氨基酸的总量高达4.322 6 mg/mL，主要种类为缬氨酸、苯丙氨酸、酪氨酸、谷氨酸。研究结果为菌株X3酶解角蛋白废弃物提供了技术支撑。
关键词：凝结芽孢杆菌；角蛋白酶；酶学性质；羽毛角蛋白；游离氨基酸
中图分类号：S19                                文献标志码：A                   DOI：10.3969/j.issn.1007-7146.2022.03.008

Abstract: In order to improve the feather keratin degrading efficiency by the strain Bacillus coagulans X3, the keratinase characteristics and feather keratin degrading effect were studied. Results showed that the optimal temperature and pH were 60℃ and 7.0～8.0, and it had good thermal stability from 70～80℃. Ca2+ and Mn2+ could greatly enhance the activity of keratinase，while its activity was strongly inhibited by Cu2+ and Ni2+. The keratinase activity showed no significantly difference with the addition of Na+, Mg2+ and Fe3+. Furthermore, the keratinase activity was inhibited by phenyl methyl sulfonyl fluoride (PMSF) and ethylene diamine tetra acetic acid (EDTA). However, β-mercaptoethanol and dithiothreitol (DTT) increased the relative enzyme activity. The enzyme could remain stable in the presence of sodium dodecyl sulfate (SDS) and dimethyl sulfoxide (DMSO). After the optimization of feather degradation conditions, the total content of free amino acids was as high as 4.322 6 mg/mL, and the main free amino acids were valine, phenylalanine, tyrosine and glutamic acid. The results can be a technological support to the utilization of Bacillus coagulans X3.
Key words: Bacillus coagulans; keratinase; enzyme characteristics; feather keratin; free amino acid
（Acta Laser Biology Sinica, 2022, 31(3): 250-255）