Purification and Characterization of Bowman-Birk Trypsin Inhibitor from Soybean

Abstract

In this paper, crude extract of a Bowman-Birk trypsin inhibitor from soybean meal was firstly isolated by a combination of , thermal denaturation, isoelectric precipitation and acetone precipitation. Then this extract was purified by DE-52 ion exchange and affinity chromatography. The results showed that soybean Bowman-Birk trypsin inhibitor (SBBI) was purified to 50.07-fold with trypsin activity of 822.31 U·mg-1. The purified SBBI gave a single protein band in SDS-PAGE electrophoresis. The accurate molecular mass of this inhibitor was determined to be 8837.46Da by MALDI-TOF. N-terminal sequence showed high homology with other serine proteinase inhibitors belonging to the Leguminosae family.