Nivulian-II a new milk clotting cysteine protease of Euphorbia nivulia latex.

Nivulian-II, new milk clotting cysteine protease has been purified from the latex of Euphorbia nivulia Buch.-Ham. Nivulian-II is a monomeric protein with an apparent molecular mass 43670.846 Da. It presents its optimum activity at pH 6.3 and temperature of 50°C. The enzyme was strongly inhibited by common thiol-blocking reagents thereby indicating that it belongs to cysteine protease family. Nivulian-II is a type of glycoprotein and its pI is 3.4. The N-terminal amino acid sequence of Nivulian-II is DFPPNTCCCICC. This sequence showed relatively low homology with several other proteases of Euphorbian plants, suggesting that the isolated enzyme is a new cysteine protease.