A Protease Isolated from the Latex of Plumeria rubra Linn (Apocynaceae) 1: Purification and Characterization

Purpose: To isolate, purify and characterize protease from the latex of the plant. Methods: Protease was isolated from the latex of Plumeria rubra Linn using acetone precipitation method and purified by a sequence of DEAE cellulose column chromatography, followed by two successive column purification in Sephadex G-50 and Sephadex G-200. The molecular weight of the purified protease was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The protease was given a trivial name, Plumerin-R. Results: Plumerin-R showed a single protein band on SDS-PAGE and molecular weight was approximately 81.85 kDa. It remained active over a broad range of temperature but had optimum activity at 55 degrees C and pH 7.0 when casein was used as substrate. Activation of the protease by a thiol-activating agent indicated the presence of sulfhydryl as an essential group for its activity. Conclusion: A protease from the latex of Plumeria rubra Linn was purified to homogeneity by a simple purification procedure and then characterized.