Wayenbam Sobhachandra Singh, Sanjenbam Kunjeshwori Devi, Sorokhaibam Jibankumar Singh, Huidrom Rully, Helena Thongam, Hijam Kiranbala Devi, Laishram Rupachandra Singh*
A new cysteine protease was purified from the latex of Thevetia peruviana (Pers.) Merr. to electrophoretic homogeneity by a procedure involving pre-treatment of the latex followed by DEAE-cellulose chromatography. The purified protease was found to be a homodimeric protein with a native molecular weight of 36 kDa. The enzyme acting on azocasein as its substrate had a specific activity of 71 units/ mg protein, and it exhibited hyperbolic kinetics with Km and Vmax values of 26.7 µM and 2.23 units/mL respectively. The enzyme was also characterized by optimum pH of 6, optimum temperature of 50°C, and T½ of 64°C. Further, specific inhibitory studies revealed the enzyme to be a cysteine protease, and the enzyme exhibited fibrinolytic activity. Peptide mass fingerprinting analysis showed that the protease was not identical with any protein characterized earlier.
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