基于动力学分析β-伴大豆球蛋白和大豆球蛋白抑制淀粉酶活性机制

Mechanism of inhibitory on porcine pancreaticα-amylase activity byβ-conglycinin and glycinin based on kinetic analysis

目的探讨β-伴大豆球蛋白(β-conglycinin,7S)和大豆球蛋白(glycinin,11S)对猪胰α-淀粉酶(porcine pancreaticα-amylase,PPA)的抑制动力学特征。方法通过测定半抑制浓度(halfmaximalinhibitory concentration,IC_(50)),结合Cornish-Bowden方程和Dixon方程,对7S和11S对PPA的抑制类型及抑制作用进行阐述。结果7S对PPA的抑制作用属于混合型竞争性抑制,而11S对PPA抑制作用主要是竞争性抑制。7S和11S的竞争性抑制常数(competitive inhibition constants,Kic)分别为3.958 mg/mL和37.083 mg/mL,7S的反竞争性抑制常数(uncompetitive inhibition constants,K_(iu))为37.394 mg/mL。7S的IC_(50)值为49.771 mg/mL。7S的Kic比K_(iu)小,这说明7S与游离的猪胰α-淀粉酶结合更密切,而与淀粉和PPA形成的中间产物结合较为疏松。结论7S和11S均通过抑制淀粉酶的活性来达到延缓淀粉类食品消化的目的,而且7S对猪胰α-淀粉酶抑制作用更强。

Objective To investigate the inhibitory kinetic characteristics of porcine pancreaticα-amylase(PPA)byβ-conglycinin(7 S)and glycinin(11 S).Methods The inhibitory types and effects of 7 S and 11 S on PPA were described by measuring the half maximal inhibitory concentration(IC_(50))and combining with Cornish-Bowden equation and Dixon equation.Results The inhibitory effect of 7 S on PPA belonged to mixed competitive inhibition,while the inhibitory effect of 11 S on PPA was mainly competitive inhibition.The competitive inhibition constants(Kic)of 7 S and 11 S were 3.958 mg/mL and 37.083 mg/mL,respectively,and the uncompetitive inhibition constants(K_(iu))of 7 S was 37.394 mg/mL.The IC_(50) value of 7 S was 49.771 mg/mL.The Kic of 7 S was smaller than that of K_(iu),which indicated that 7 S bound more closely to free porcine pancreaticα-amylase,but loosely bound to the intermediates formed by starch and PPA.Conclusion Both 7 S and 11 S achieve the purpose of delaying the digestion of starchy foods by inhibiting the activity of amylase,and 7 S has a stronger inhibitory effect on porcine pancreaticα-amylase.