Abstract

• α-Amylase (EC 3.2.1.1) break down long-chain carbohydrate, ultimately yielding maltotriose and maltose. In this research, α-amylase from germinating maize grains was extracted by using sodium chloride and acetate buffer pH 5.6 solution. Qualitative examination of α-amylase activity in the solution was carried out by using iodine staining method. Soluble starch was used as a substrate for α-amylase activity determination by measuring the absorbance of maltose using UVvisible spectrophotometer. α-Amylase activities during germinating of maize grains were studied by determining the daily enzyme activity. The maximum α-amylase activity was found on third day of growth. The protein content of enzyme solution was determined by Biuret method. The specific activity of enzyme solution was calculated to be 12.035 µmol min-1 mg -1 . The enzyme unit (EU) of crude α-amylase was found to be 165.01 EU per gram of maize grains. The optimum pH of α-amylase was found to be 5.6 in acetate buffer and optimum temperature was found to be 60 °C. The values of Km and Vmax treated statistically using the linear regression method were compared with various graphically methods (Michaelis-Menten, Lineweaver-Burk, Eadie-Hofstee and Hanes-Wilkinson). The Km and Vmax values of α-amylase were found to be 0.19210-2 g mL-1 and 1.97810-3 M min-1 , respectively, from Lineweaver-Burk plot. The reaction order (n) for α-amylase was calculated to be 1.203 proving that the reaction order is first order. The activation energy (Ea) of α-amylase-catalyzed reaction was calculated to be 4.977 kcal mol-1 . In this research, cassava sample was used as a starch source for the preparation of maltose. The maltose content in the prepared sample was determined by using Dinitrosalicylic acid method.