Purification And Partial Characterization Of Ginger Protease

Ginger protease is a new kind of protease discovered in plant after papain, ficin and bromelain which is homologous in primary structure and advanced structure with those papain family members, thus become a new member of papain family. Ginger protease(GP-II) cleaves peptides and proteins with proline at the P2 position.The unusal specificity for proline makes GP-II an attractive tool for protein sequencing and identification of stably folded domain in proteins.Ginger protease is found to have clotting activity.The traditional food of our country ,"Jiangzhuang milk", use ginger juice as clotting agent and the component which responsible for milk clotting in the juice is verified as ginger protease. The milk clotting activity makes ginger protease an attractive substitute for the calf rennet in cheesemaking. In addition, ginger protease can be used in many other industries.In this study, a effective separating and purifying plan has been worked out on the basis of former researchers' performance and the critical data of each step were determinated. Ginger rhizome was made into acetone powder , then the protease was extracted with a certain buffer. After ammonium sulfate precipitate and chromatography on DEAE-cellulose the protease was purified. The gained sample showed a single protein band on SDS-PAGE. With the purified sample, the research of milk clotting was carried out. In experiments results below were gained,1.Ginger protease is a kind of acid protease.2.Ginger protease mainly exists in the root-like stem of the ginger plant.3.Freezing of ginger is helpful for the enhance of extract ratio.4.The residue ginger rhizome after supercritical fluid extraction cannt be used as raw material for production of ginger protease.5.Sample Cl has milk clotting activity. 1 unit of proteolytic activity amount to 15 rennet unit. But sample C2 showed no milk clotting activity6.Sample Cl can hydrolyze whole P -caseins and much of a s -caseins rapidly. But in the process of clotting of reconstituted milk it shows little proteolytic activity. Sample C2 has little proteolytic activity both on caseins and reconstituted milk.