Purification and Characterization of Extracellular Phospholipase A2 from Human Synovial Fluid in Rheumatoid Arthritis1

Abstract

Extracellular phospholipase A₂ was purified about 1.7 × 10⁵ fold to near homogeneity from human synovial fluid of rheumatoid arthritis by sequential use of column chromatographies on heparin-Sepharose, butyl-Toyopearl, and reversed-phase HPLC. The final preparation showed a single band on SDS-polyacrylamide gel electrophoresis, and its molecular mass was estimated to be approximately 13, 700 daltons. The purified enzyme had a pH optimum of 9.0 and required Ca²⁺ for maximum activity. It hydrolyzed phosphatidylethanolamine more effectively than phosphatidylserine and phosphatidylcholine. These properties were similar to those of an extracellular phospholipase A₂ detected in the peritoneal cavity of caseinate-treated rats.