柚皮素与α-淀粉酶相互作用的研究

Interaction of Naringenin and α-Amylase

摘要:

本文研究了柚皮素与α-淀粉酶的相互作用。柚皮素与α-淀粉酶反应形成复合物，从而对α-淀粉酶的催化活性、荧光特性以及柚皮素的抗氧化活性产生相应的影响。采用酶动力学方法和荧光光谱法研究了柚皮素对α-淀粉酶的抑制作用。在pH 6.8、37 ℃条件下反应20 min，柚皮素（1 mg/mL，0.05 mL）对α-淀粉酶（0.33 U/mL, 0.2 mL）催化活性的抑制率达到36.6 %。该抑制作用是以非竞争性方式进行。柚皮素对α-淀粉酶的内源性荧光产生有规律的猝灭作用，其方式以静态猝灭为主。二者主要通过疏水作用力发生结合反应形成复合物，有1个结合位点，表观结合常数约105 L/mol。另一方面，由于与α-淀粉酶发生复合反应，柚皮素的还原力和抗亚油酸氧化的活性也有一定程度的降低，而可能导致其生物活性发生改变。

Abstract:

The complex formed by naringenin and α-amylase resulted in the decreased antioxidant activity of naringenin and catalytic activity of enzyme, as well as efficient quenching of the intrinsic fluorescence of α-amylase. The inhibitory effect of naringenin on α-amylase was studied by enzymatic kinetics and fluorescence spectroscopy. α-Amylase (0.33 U/mL, 0.2 mL) was treated by naringenin (1 mg/mL, 0.05 mL) under pH 6.8, 37 ℃ for 20 min, the inhibition rate reached 36.6 %. The mechanism of inhibition effect was noncompetitive inhibition. The regular quenching of intrinsic fluorescence of α-amylase was induced by naringenin as a quencher in physiological condition, and the majority was static quenching. Naringenin binded with α-amylase to form a new complex was using hydrophobic interaction. An α-amylase molecule provided one binding site for a naringenin molecule, with the apparent binding constant Kb around 105 L?mol-1. The total antioxidant activity in linoleic acid emulsion and reducing power of naringenin were also inhibited by α-amylase, which might lead to the change of biological activity of naringenin.