Physicochemical and enzymatic properties of benzyl isothiocyanate derivatized proteinases

This paper deals with interactions of benzyl isothiocyanate (benzyl-ITC) with cysteine proteases (bromelain and papain) as well as with serine proteases (trypsin and alpha-chymotrypsin), The derivatives formed with different amounts of benzyl-ITC (10-125 mg of benzyl-ITC/g of protein) have been characterized in terms of their physicochemical and proteolytic properties. Detectable changes in the chromatogram pattern of the derivatives coupled with an increase in hydrophobicity were documented by RP-HPLC. Furthermore, the isoelectric point was shifted to the lower pH values. SDS-PAGE and MALDI-MS of the chymotrypsin derivatives showed distinctive molecular changes. The other major subject of the present paper shows the effects of benzyl-ITC derivatization on proteolytic activity of bromelain, papain, trypsin, and alpha-chymotrypsin. In general, a decrease of enzyme activity was documented for the proteolysis of casein and myoglobin as substrates.