白杨素对胰脂肪酶的抑制作用及机制

Inhibitory interaction and mechanism of chrysin on pancreatic lipase

应用多种光谱法结合分子对接技术研究了白杨素对胰脂肪酶的抑制作用及抑制机制。结果表明白杨素以竞争方式可逆地抑制胰脂肪酶活性,IC_(50)值为(8.21±0.02)×10^(-4)mol L^(-1)。白杨素与胰脂肪酶在氢键和疏水作用力驱动下形成了基态复合物并通过静态方式猝灭胰脂肪酶的内源荧光,其结合常数为10^(-4)L mol^(-1)数量级,白杨素在胰脂肪酶上的结合位点更接近色氨酸残基。圆二色谱分析表明,白杨素与胰脂肪酶的结合使胰脂肪酶的结构变得更加紧密。分子对接显示白杨素与胰脂肪酶活性中心的氨基酸残基Glu188、Pro194、Gln220、Thr221、Val322、Ser323发生相互作用。白杨素抑制胰脂肪酶的机制可能是由于白杨素与活性中心的一些氨基酸残基发生相互作用,导致酶结构变得紧密,阻止了底物进入活性中心而避免其被氧化,从而降低了胰脂肪酶的催化效率。该研究对于白杨素作为胰脂肪酶新型抑制剂及抗肥胖营养素的开发具有参考价值。

In this paper,various spectroscopic methods combined with molecular simulation techniques were used to study the inhibitory effect and mechanism of chrysin on pancreatic lipase.The results showed that chrysin reversibly inhibited pancreatic lipase activity in a competitive manner with an IC_(50) value of(8.21±0.02)×10^(-4)mol L^(-1).A ground state complex between chrysin and pancreatic lipase was formed which was driven by hydrogen bonds and hydrophobic forces and quenched the endogenous fluorescence of the enzyme in a static manner.Their binding to constant was the magnitude of 10^(-4)mol L^(-1)and the binding site of pancreatic lipase for chrysin was closer the tryptophan residues.Analysis of the circular dichroism spectra revealed that the binding of chrysin with pancreatic lipase made the structure of the enzyme more compact.The molecular docking showed that chrysin interacted with the residues Glu188,Pro194,Gln220,Thr221,Val322 and Ser323 in the active center of the enzyme.It was inferred that the inhibitory mechanism of chrysin on pancreatic lipase was probably due to the fact that the interaction of chrysin with the amino acid residues in the active center of the enzyme led to the more constrictive structure of pancreatic lipase,prevented the substrate entering the active center from being oxidized,thereby reducing the catalytic efficiency of pancreatic lipase.This study has reference values for the development of chrysin as new inhibitor against pancreatic lipase and anti-obesity nutrient.