College of Food Science and Technology, Yunnan Agricultural University, Kunming 650201, Yunnan, China.
College of Food Science and Technology, Yunnan Agricultural University, Kunming 650201, Yunnan, China; Yunnan Engineering Technology Research Center for Processing of Livestock Products, Kunming 650201, Yunnan, China.
Food Res Int. 2022 Sep;159:111598. doi: 10.1016/j.foodres.2022.111598. Epub 2022 Jun 30.
The protein extract of Moringa oleifera flowers is reported to have milk-clotting activity (MCA), but information regarding its protease is unclear. In this study, two milk-clotting proteases (MoFP 12 and MoFP 13) with molecular weights of 42.304 kDa and 31.741 kDa, respectively, were isolated and identified from M. oleifera flowers using liquid chromatography-mass spectrometry (LC-MS/MS). Bioinformatics analysis showed that these two milk-clotting proteases were primarily involved in hydrolase activity and catabolic process, and exhibited hydrophilicity. The secondary structure of MoFP 12 consisted of 43.65% helix, 13.23% strand, and 43.12% coil, and MoFP 13 consisted of 26.51% helix, 20.14% strand, and 53.35% coil. The proteases were stable in the pH range of 5.0 to 8.0 and showed their maximum MCA at 70℃. Additionally, by investigating the effect of proteases on caseins, κ-casein (CN) was observed to preferentially be hydrolyzed by the two proteases, followed by α-CN, and to a lesser extent β-CN. These findings revealed the main milk-clotting proteases in M. oleifera flowers and its milk-clotting properties, indicating its potential for application in the dairy and food sectors, especially in the cheese-making industry.
辣木花的蛋白质提取物据报道具有凝乳活性（MCA），但关于其蛋白酶的信息尚不清楚。在这项研究中，两种分子量分别为 42.304 kDa 和 31.741 kDa 的凝乳蛋白酶（MoFP 12 和 MoFP 13）使用液相色谱-质谱联用（LC-MS/MS）从辣木花中分离和鉴定。生物信息学分析表明，这两种凝乳蛋白酶主要参与水解酶活性和分解代谢过程，并表现出亲水性。MoFP 12 的二级结构由 43.65%的螺旋、13.23%的链和 43.12%的线圈组成，MoFP 13 由 26.51%的螺旋、20.14%的链和 53.35%的线圈组成。蛋白酶在 pH 值为 5.0 到 8.0 的范围内稳定，并在 70℃时表现出最大的 MCA。此外，通过研究蛋白酶对酪蛋白的影响，发现两种蛋白酶优先水解 κ-酪蛋白（CN），其次是 α-CN，β-CN 的水解程度较小。这些发现揭示了辣木花中主要的凝乳蛋白酶及其凝乳特性，表明其在乳制品和食品行业，特别是奶酪制造行业中有应用潜力。
