Title:Purification and Characterization of a Thermostable Caseinolytic Serine Protease from the Latex of Euphorbia heterophylla L.
Volume: 22
Issue: 9
Author(s): Sorokhaibam J. Singh, Laishram R. Singh, Sanjenbam K. Devi, Senjam S. Singh, Chingsubam B. Devi and Huidrom Rully
Affiliation:
Keywords:
Euphorbia heterophylla, plant latex, protease, serine protease.
Abstract: A new thermostable caseinolytic serine protease was purified from the latex of Euphorbia
heterophylla L. to electrophoretic homogeneity by a procedure involving successive steps of pretreatment
of the latex, PEG fractionation, CM-cellulose chromatography and DEAE-cellulose chromatography.
The purified protease was found to be a monomeric protein of molecular weight 77.2 kDa. It
exhibited caseinolytic activity with hyperbolic azocasein saturation with Vmax and Km values of 0.11
units.mL-1 and 0.55 mg.mL-1 respectively. Specific inhibitory studies revealed the enzyme to be a serine
protease. The protease was characterized by pH optimum of 8.0 and high thermostability with T1/2
of 75°C. Based on the results of peptide mass fingerprinting analysis, the protease was shown to be a new protein not
characterized earlier.