Fractionation of Angiotensin Converting Enzyme(ACE) Inhibitory Peptides from Soybean Paste

Abstract

Angiotensin converting enzyme(ACE) inhibitory peptides lowering blood pressure were fractionated from a commercial soybean paste(Doenjang). When the freeze-dried sample of soybean paste was extracted with cold water, the recovery yield of total nitrogen(TN) was shown to be 73.3% in 30 minutes. The cold water extract was filtered through PM-10 membrane(Amicon) for 3 hours in order to remove high molecular weight polypeptides. The TN and salt of ultrafiltrate were recovered to 80.8% and 99.2%, respectively, and its ACE was . When the ultrafiltrate was divided into 7 fractions by reverse phase prep-HPLC, F5 fraction showed the highest ACE inhibitory activity () and salt could be collected into F1 fraction. Subsequently, the F5 fraction was divided into another five fractions by ion exchange prep-HPLC, all of which appeared to be high ACE inhibitory activity(). Among them, F53 fraction had the highest ACE inhibitory activity, and its main amino acid component was found to be histidine.