Chemical composition and characteristics of alpha-amylase inhibitor

ABSTRACT

In this study chemical constituents and characteristics of alpha amylase inhibitor extracted from kidney bean Giza 133 and wheat Giza 164 were studied. Results indicated that the purified alpha amylase inhibitors of kidney bean Giza 133 contained more total carbohydrate content [14.4%] than wheat Giza 164 [1.2%], in addition to the differences in amino acid content for both samples. The alpha amylase inhibitor characteristics indicated that the molecular weight of kidney bean Giza 133 [47.000 Da] was higher than both wheat Giza 164 [24.000 Da] and human salivary alpha-amylase [32.000 Da] and lower than enzyme-inhibitor complex [61.000 Da]. The low activity of both human and pancreatic alpha amylase was achieved using low concentration of kidney bean inhibitor [1.56 and 1.95 UI] compared with higher concentration [4.69 and 5.47 UI] of wheat Giza 164. The addition of salt [NaCl and bromide] in the purification step increased the inhibitor activity up to 80, 91%, and the inhibitor reaction rate reached maximum at ratio 11 [Inhibitor [I] Enzyme [E]]. Results also indicated that the low dissociation constant of kidney bean inhibitor gave stability to the I-E complex at pH 6.9. Increasing the pH values prevent further inhibition and the reaction is irreversible, while raising the temperature up to 37°C reverse the inhibition reaction to its primary rate