麦谷蛋白和麦醇溶蛋白抑制α-淀粉酶活性的动力学研究

Study of Inhibitory Kinetics of Glutenin and Gliadin from Wheat on α-Amylase Activity

为了探讨麦谷蛋白和麦醇溶蛋白对猪胰α-淀粉酶(PPA)的抑制动力学特征。通过测定半抑制浓度(IC50),结合Dixon方程和Cornish-Bowden方程,探究麦谷蛋白和麦醇溶蛋白对PPA的抑制类型及抑制机理。结果表明,麦谷蛋白对PPA的抑制作用属于混合型竞争性抑制,麦醇溶蛋白对PPA的抑制作用属于竞争性抑制。麦谷蛋白和麦醇溶蛋白的竞争性抑制常数(Kic)分别为(20.533±3.582),(49.619±5.949)mg/mL,麦谷蛋白的反竞争性抑制常数(Kiu)为(49.358±9.779)mg/mL。麦谷蛋白和麦醇溶蛋白的IC50值分别为(14.014±1.089),(33.193±0.621)mg/mL。对于麦谷蛋白而言,Kic比Kiu小,表明麦谷蛋白与游离PPA的结合要比与淀粉和PPA形成的中间产物的结合更紧密。麦谷蛋白较麦醇溶蛋白对PPA抑制作用更强。总之,麦谷蛋白和麦醇溶蛋白均可以抑制淀粉酶的活性,从而延缓淀粉类食品的消化。研究结果将丰富典型蛋白质组分调控食物淀粉消化的机理,为碳水化合物限制饮食体系低GI食品的开发提供理论指导。

The objective of this study was to investigate the porcine pancreatic α-amylase(PPA) inhibitory activity of glutenin and gliadin.The half maximal inhibitory concentration(IC50) was determined,and the kinetics of inhibition were investigated using Dixon and Cornish-Bowden plots.The results showed glutenin was mixed inhibitors with competitive and uncompetitive inhibitory impacts on α-amylase,while gliadin showed competitive inhibitory effects on α-amylase.The competitive inhibition constants(Kic) of glutenin and gliadin were(20.533±3.582),(49.619±5.949) mg/mL,respectively,and the uncompetitive inhibition constants(Kiu) of glutenin was(49.358±9.779) mg/mL.The IC50 values of glutenin and gliadin were(14.014±1.089) mg/mL and(33.193±0.621) mg/mL,respectively.For glutenin,the lower Kicvs.Kiusuggested that glutenin bound more tightly to free PPA than the PPA-starch complex.Compared with gliadin,glutenin displayed a stronger inhibitory effect on α-amylase.These results indicated that glutenin and gliadin may delay the digestion of starchy foods by inhibiting starch hydrolytic enzymes.And these results will enrich the mechanism of protein regulation of starch digestion.The findings are also of important practical value for the development of carbohydrate-restricted diet and protein-based functional foods.