Available online at www.ajofai.info Research Article

Trypsin inhibitor was isolated from navy bean (Phaseoulus vulgaris), red kidney bean (Phaseoulus vulgaris L) and adzuki bean (Vigna angularis) from the Royal Project Foundation, Thailand. Extraction of navy bean and red kidney bean with 0.02 M NaOH showed the highest recovery of trypsin inhibitor, while water was the best extractant for adzuki bean. The extraction time significantly affected the trypsin inhibitor recovery (p<0.05). Two hours of extraction gave the highest yield of trypsin inhibitor from three legumes. The trypsin inhibitors were estimated to have molecular weight of 132, 118 and 13 kDa under non-reducing conditions for navy bean, red kidney bean and adzuki bean, respectively. The inhibitory activities of the inhibitor from these legumes were lost when they were treated with β-mercaptoethanol, indicating the subunit of polypeptide in its composition