Before attempting to extract an enzyme from an organism,some preliminary considerations should be made.first of all,it is essential to know the location of the enzyme within the cell,and whether the enzyme is present in free solution or bound to a membrane. For example,soluble enzymes may be extracted from cells simply by the disruption of membranes.the enzyme being extracted remains in solution while the cell debris is removed by centrifugation.techniques for the purification of the extracted enzyme include electrophoresis,ion exchange chromatography,gel filtration and affinity chomatography.enzyme assay should be preformed after each purification step,and the specific activity of each fraction determoned.when this has been achieved,the purity of the preparation should be checked by a variety of techniques,including ultracentrifugation,electrophoresis and HPLC.after purification,the molecular weight of the enzyme may be determined by gel SDS-gel electrophoresis