School of Food Science, Henan University of Technology, 100 Lianhua Street, Zhengzhou 450001, Henan, China; Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, No. 11/33, Fucheng Road, Haidian District, Beijing, China; State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, Jiangsu, China.
State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, Jiangsu, China.
Int J Biol Macromol. 2019 Apr 15;127:555-562. doi: 10.1016/j.ijbiomac.2019.01.082. Epub 2019 Jan 18.
The influence of polyols on Rhizopus chinensis lipase (RCL) was investigated under high pressure. The poor stability of RCL was observed at 500 MPa at 60 °C without polyols which protected RCL against the loss of activity. The lipase is more stable in phosphate buffer than in tris buffer despite the protection of polyols. The activity was maintained 63% by the sorbitol of 2 mol/L in Tris-HCl buffer but 73% in phosphate buffer after the treatment at 500 MPa and 60 °C for 25 min. The same protective effects could be observed at 1 mol/L of sorbitol, erythritol, xylitol, and mannitol. However, further increase of hydroxyl group number could not significantly improve the enzyme stability. The protection of polyols on RCL appears to depend on both of the polyol nature and the hydroxyl group number. Together with fluorescence spectra, circular dichroism spectra indicated that the chaotic conformation of RCL under high pressure became more ordered with 1 mol/L sorbitol. The results showed that sorbitol effectively stabilized the lipase conformation including the hydrophobic core under extreme conditions. It might be attributed to the interaction of polyols with RCL surface to modify intra-/intermolecular hydrogen bonds, maintaining the hydrophobic interactions within RCL.
研究了多元醇对高温高压下里氏木霉脂肪酶（RCL）的影响。在没有多元醇保护的情况下，RCL 在 60°C 时的 500 MPa 下稳定性较差，导致其失去活性。尽管有多元醇的保护，脂肪酶在磷酸盐缓冲液中的稳定性仍高于三羟甲基氨基甲烷缓冲液。在 500 MPa 和 60°C 下处理 25 min 后，2 mol/L 山梨醇在 Tris-HCl 缓冲液中可保持 63%的活性，而在磷酸盐缓冲液中可保持 73%的活性。在 1 mol/L 的山梨醇、赤藓糖醇、木糖醇和甘露醇中也可以观察到相同的保护效果。然而，增加羟基数并不能显著提高酶的稳定性。多元醇对 RCL 的保护作用似乎取决于多元醇的性质和羟基数。荧光光谱和圆二色光谱表明，在高压下，1 mol/L 山梨醇使 RCL 的混沌构象变得更加有序。结果表明，山梨醇在极端条件下有效地稳定了脂肪酶的构象，包括疏水区。这可能归因于多元醇与 RCL 表面的相互作用，从而改变了分子内/分子间氢键，维持了 RCL 内部的疏水相互作用。
