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Characterization of proteoglycan degradation by calpain
K Suzuki1, K Shimizu, T Hamamoto
1Department of Orthopedic Surgery, Faculty of Medicine, Kyoto University, Japan.
The Biochemical Journal
|August 1, 1992
Summary
Cartilage proteoglycans are degraded by pig kidney calpain II, a calcium-dependent enzyme. Proteoglycans bind calcium ions, potentially regulating calpain II activity in connective tissues.
Area of Science:
- Biochemistry
- Connective Tissue Research
- Enzymology
Background:
- Cartilage proteoglycans are crucial structural components of connective tissue.
- Calcium-dependent cysteine proteinases, like calpain II, are implicated in tissue degradation.
Purpose of the Study:
- To investigate the degradation of cartilage proteoglycans by pig kidney calpain II.
- To elucidate the mechanism of proteoglycan degradation and the role of calcium ions.
Main Methods:
- Incubation of cartilage proteoglycan aggregate and monomer with purified pig kidney calpain II under neutral conditions.
- Analysis of proteolysis products and calcium ion binding capacity of proteoglycans.
Main Results:
- Calpain II rapidly degraded proteoglycan aggregate and monomer via limited proteolysis of the core protein.
- Hyaluronic acid-binding region was lost, and degradation products were larger than those from papain or trypsin digestion.
- Proteoglycans adsorbed significant amounts of Ca2+ ions, which was lost upon desulfation of glycosaminoglycans.
Conclusions:
- Calpain II affects the form of proteoglycans in connective tissue.
- Cartilage proteoglycans regulate Ca2+-dependent enzymes, including calpains, through calcium ion chelation.