Religiosin B, a milk-clotting serine protease from Ficus religiosa

A novel milk-clotting serine protease, named religiosin B, is purified from Ficus religiosa. The molecular mass of the protein is 63,000 with pI value of pH 7.6. The proteolytic activity of the enzyme is strongly inhibited by phenylmethanesulfonyl fluoride (PMSF) and chymostatin. Religiosin B acts optimally at pH 8.0–8.5 and temperature 55 °C. The molar absorption coefficient of the enzyme is 149,725 M−1cm−1 with 23 tryptophan, 15 tyrosine and 7cysteine residues per molecule of the enzyme. The enzyme shows broad substrate specificity with natural as well as synthetic substrates. Religiosin B is highly stable against denaturants and metal ions as well as over a wide range of pH and temperature. The de novo sequencing confirms the novelty of the enzyme. In addition to its high milk-clotting ability, it could be used in the cheese industry, as well as other food and biotechnological industries.