Department of Food Science and Engineering, Shanghai Food Safety and Engineering Research Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China.
College of Biological Science and Engineering, Fuzhou University, Fuzhou 350108, China.
Food Funct. 2017 Jan 25;8(1):323-332. doi: 10.1039/c6fo01215a.
The inhibition of α-glucosidase decreases postprandial blood glucose and therefore plays an important role in the treatment of type 2 diabetes mellitus. The present study investigated and characterized a peptide fraction of sericin hydrolysate, the kinetics of peptide-induced inhibition of α-glucosidase, and the interaction mechanism between the peptides and α-glucosidase. The fraction that eluted with 0.4 M NaCl (F5-SPs) on a DEAE-cellulose column exhibited significant inhibitory activity with an IC of 41 ± 1.94 μg mL. A kinetics analysis revealed that the F5-SP-induced inhibition was a reversible and parabolic mixed-type inhibition with a K value of 86.63 ± 0.014 μg mL. F5-SPs can bind to α-glucosidase at multiple sites to alter the conformation of α-glucosidase. F5-SPs were found to be rich in Gly, Ser, Glu, Tyr, Arg, and Pro, and had a sericin-conserved sequence SEDSSEVDIDLGNLG, as analyzed by Nano LC-MS/MS. Fluorescence spectra analysis showed that F5-SPs quenched the intrinsic fluorescence of α-glucosidase by a static quenching mechanism, and circular dichroism analysis suggested that the binding of F5-SPs to α-glucosidase resulted in the alteration of the secondary structure of an enzyme. The results of this study support the dietary recommendation of F5-SPs for the treatment of type 2 diabetes.
α-葡萄糖苷酶抑制剂可降低餐后血糖，因此在治疗 2 型糖尿病方面发挥着重要作用。本研究调查并鉴定了丝胶水解物的肽段，研究了肽诱导α-葡萄糖苷酶抑制的动力学以及肽与α-葡萄糖苷酶之间的相互作用机制。在 DEAE-纤维素柱上用 0.4 M NaCl 洗脱的级分（F5-SPs）显示出显著的抑制活性，IC 为 41±1.94μg·mL。动力学分析表明，F5-SP 诱导的抑制是一种可逆的抛物线型混合抑制，K 值为 86.63±0.014μg·mL。F5-SPs 可以在多个部位与α-葡萄糖苷酶结合，改变α-葡萄糖苷酶的构象。通过 Nano LC-MS/MS 分析发现，F5-SPs 富含 Gly、Ser、Glu、Tyr、Arg 和 Pro，具有丝胶保守序列 SEDSSEVDIDLGNLG。荧光光谱分析表明，F5-SPs 通过静态猝灭机制猝灭了α-葡萄糖苷酶的内源性荧光，圆二色性分析表明 F5-SPs 与α-葡萄糖苷酶的结合导致了酶二级结构的改变。本研究结果支持将 F5-SPs 作为治疗 2 型糖尿病的饮食推荐。
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