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KMID : 1007520010100010020
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Food Science and Biotechnology
2001 Volume.10 No. 1 p.20 ~ p.26
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Properties of α - Amylase Inhibitor Isolated from White Kidney Bean (Phaseolus vulgaris)
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Lee, Kap Sang
Park, Seung Taeck/Chun, Seung Ho/Ryu, Il Hwan
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Abstract
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Two inhibitors of α-amylase, I-1-f and I-2-f, were extracted and purified from white kidney bean (Phaseolus vulgaris). The optimal temperature for reaction of α-amylase inhibitors I-1-f and I-2-f was 40℃ and optimal pHs were 5.5 and 6.0, respectively. As the ionic strength of the preincubation buffer increased from 0.10 M to 0.90 M, the inhibition rate by the two inhibitors increased by 3 fold. The inhibitors reacted specifically with animal α-amylase, however they did not react with those (delete) plant, bacterial and fungal α-amylase. The dissociation constants for I-1-f and I-2-f were 2.7×10^(-4) M, and 3.4×10^(-4) M, respectively. Both inhibitors worked as a noncompetitive inhibitor. As α-amylase reaction products, maltose inhibited the activity of only I-2-f and, while glucose inhibited the activities of both I-1-f and I-2-f. Treatments such as glyco chain removal, and modification of histidine and tryptophan inhibited α-amylase inhibitors activity. The inhibitors given to rats, with starch meal through a stomach tubing, reduced the symptom of hyperglycemia resulting by prevention of starch utilization. After a starch meal was given to the rat through a stomach tubing, the inhibitors given thereafter reduced the symptom of hyperglycemia by preventing starch utilization.
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