Extraction And Characterization Of Alpha-amylase Inhibitor From Some Cereals And Legumes

摘要

Alpha-amylase inhibitor extracted from different sources, i.e., wheat grains (Sohag 2 and Giza 164), legume seeds such as cow pea (Canm 7 and Giza 3), and kidney bean (Giza 6 and Giza 133) was purified and tested for activity using human salivary and pancreatic alpha-amylase. Results showed that the alpha-amylase inhibitor activity from samples studied were 120 to 285 unit / mg protein. The inhibitor was found to be stable at pH range from 2 to 4. It was also stable to digestion by proteolytic enzymes (pepsin and trypsin). The inhibition was faster at 37 ℃ than at 25 ℃, The results showed that the degree of thermal stability of alpha-amylase inhibitor extracted from kidney bean (Giza 133) was at 35-37 ℃, activity was decreased on 50 ℃ for 5 hr. Increased of pre-incubation time between inhibitor and both alpha-amylase enzymes at 37 ℃ increased the rate of inhibition of these enzymes and the complex formation between them from 60 - 80 % in 30 min, while addition of these enzymes to the mixture containing inhibitor and substrate (without pre-incubation) decrease the percent inhibition. Therefore, an evidence of specific interference of the alpha-amylase inhibitor with starch availability was established. Such possibilities will have valuable interest in the field of special dietary food preparations for diabetes and over weight reduction purposes.