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Biochemical characterization of soluble phospholipase A2 from rheumatoid synovial fluid
H Gonzalez-Buritica1, D M Smith, R A Turner
1Department of Medicine, Section on Rheumatology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27103.
Abstract:
Radiolabeled E. coli, Phosphatidylethanolamine (PE) and Phosphatidylcholine (PC), were used to characterize the phospholipase A2 (PLA2) activity in synovial fluid (SF) from rheumatoid arthritis (RA) patients. Cell-free fractions of SF contain a PLA2 enzyme that preferentially releases [14C]oleic acid from E. coli, requires calcium and is optimally active at neutral pH. Purified PE, but not PC is also readily degraded by the soluble enzyme. A cell-associated PLA2 present in sonicates of SF mononuclear cells and neutrophils preferentially releases [3H]AA from E. coli. These studies suggest the presence of at least two different enzymes with activity of PLA2 in rheumatoid SF.