Isoelectric fractionation and some properties of a protease from soyabean seeds

A protease, capable of hydrolysing benzoyl DL -arginine p-nitroanilide(BAPA), and L-amino acid β-naphthylamide derivatives, was purified, by isoelectric focusing in the region pH 3–6, from dormant and 6-day germinated soyabean seeds. The enzyme was focused at pH 4·80. The K_m value using BAPA as substrate was found to be 5·03 × 10^?4M . Maximum activity of the enzyme towards BAPA was obtained in the pH 8·2–8–5 region. Slight activation was observed in the presence of 0·05 M concentration of Ca²⁺ and Mg²⁺ ions. The protease lacked caseinolytic activity, and was not inhibited by Kunitz soyabean trypsin inhibitor.