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Multiple forms of phospholipase A2 in arthritic synovial fluid
J J Seilhamer1, S Plant, W Pruzanski
1California Biotechnology Inc., Mt. View 94043.
Journal of Biochemistry
|July 1, 1989
Summary
Researchers purified phospholipase A2 (PLA2) from human arthritic synovial fluid, identifying two main forms. These enzymes, crucial in inflammatory conditions, were characterized by their activity and molecular weight.
Area of Science:
- Biochemistry
- Enzymology
- Rheumatology
Background:
- Synovial fluid in arthritis contains enzymes like phospholipase A2 (PLA2).
- Understanding PLA2 activity in arthritic joints is key to inflammatory disease research.
Purpose of the Study:
- To purify and characterize phospholipase A2 (PLA2) from human arthritic synovial fluid.
- To identify and differentiate distinct PLA2 isoenzymes present in synovial fluid.
Main Methods:
- Purification of PLA2 using preparative High-Performance Liquid Chromatography (HPLC).
- Enzyme activity assays using various substrates (phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine) and conditions (pH, detergents, Ca2+).
- Protein characterization via SDS-polyacrylamide gel electrophoresis and N-terminal sequencing.
Main Results:
- Two major PLA2 peaks (A and B) were isolated from synovial fluid.
- Peak A was abundant in rheumatoid, osteoarthritis, and psoriatic arthritis fluids.
- Peak B showed distinct activity profiles with Tris or sodium deoxycholate (DOC) and a longer HPLC retention time.
- Both PLA2 peaks were approximately 14,000 Da and required Ca2+ for activity.
- Optimal activity for both peaks occurred between pH 8.0-9.0 in DOC/phosphatidylcholine (PC) micelles.
Conclusions:
- Human arthritic synovial fluid harbors distinct forms of phospholipase A2.
- Characterization of these PLA2 isoenzymes provides insights into their potential roles in arthritis pathogenesis.
- The identified PLA2 forms share some properties but differ in substrate preference and response to activators.