Two proteinaceous a-amylase inhibitors termed aAI-Pa1 and aAI-Pa2 were purified from seeds of a cultivated tepary bean
(Phaseolus acutifolius A. Gray, cv. PI311897). The two inhibitors differed in their specificity towards a-amylases of insect pests such
as bruchids, although neither showed any inhibitory activity against a-amylases of mammalian, bacterial or fungal origin. aAI-Pa2
resembles two common bean inhibitors, aAI-1 and aAI-2, in several characteristics such as N-terminal amino acid sequences and
oligomeric structure being composed of a and b subunits. In contrast aAI-Pa1 is composed of a single glycopolypeptide with a
molecular mass of 35 kDa, and its N-terminal amino acid sequence resembled that of seed lectins in tepary bean and common bean.
The information on the two tepary bean a-amylase inhibitors may be useful not only for providing insight into critical structure for
the specificity towards different a-amylase enzymes but also for enhancing insect resistance in crops. # 2001 Elsevier Science Ltd.
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