title: Purification and Characterization of a Thermostable Caseinolytic Serine Protease from the Latex of Euphorbia heterophylla L.
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.
authors.forename: Sorokhaibam J
authors.initials: SJ
authors.lastname: Singh
authors.affiliation: Laboratory of Protein Biochemistry, Biochemistry Department, Manipur University, Canchipur, Imphal- 795003, India. rslaishram@yahoo.com.
authors.forename: Laishram R
authors.initials: LR
authors.lastname: Singh
authors.forename: Sanjenbam K
authors.initials: SK
authors.lastname: Devi
authors.forename: Senjam S
authors.initials: SS
authors.lastname: Singh
authors.forename: Chingsubam B
authors.initials: CB
authors.lastname: Devi
authors.forename: Huidrom
authors.initials: H
authors.lastname: Rully
mesh_terms: D004795:Enzyme Stability; D028481:Euphorbia / Q000201:enzymology*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007840:Latex / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D057057:Serine Proteases / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D007840:Latex; D010940:Plant Proteins; D057057:Serine Proteases