Porcine phospholipaseA2 expressed in E. coli as a fusion protein was isolated, renatured and specifically cleaved by trypsin as described in (1). Active phospholipaseA2, was purified to homogeneity on a column of PBE-94 over a pH region 7.4-4.5. Using this method, several phospholipase A2 mutant enzymes have now been purified in a single step and all behaved identically during chromatofocusing. The method will therefore be extremely useful not only for those interested in understanding the structure-function relationships of phospholipaseA2 but also for preparing the enzyme in large quantities for industrial and pharmaceutical purposes.