Degradation of rat chondrosarcoma proteoglycans by a neutral metalloprotease from rabbit chondrocytes

Abstract

Rat chondrosarcoma proteoglycan aggregate with radiolabeled core protein was digested with a chondrocyte metalloprotease (CMP) or clostripain (CP) at neutral pH. The rates of product formation and the sizes and antigenicities of the products were studied using column chromatography and monoclonal antibodies. Sixteen percent of [³⁵S]methionine label and 17–18% of [³H]serine label in core protein were freed from glycosaminoglycan bound peptides by 50U/ml (760 μg/ml) of CP or 10 μg/ml (estimated) of CMP in 180 min. The CP reaction was almost complete at 5 minutes while the CMP reaction proceeded slowly from 5 to 180 min. The chondroitin-sulfate rich fragments were smaller after CP than CMP treatment. The 180 min CMP digest contained protein that migrated in 2 peaks on Sepharose CL6B. These two peaks corresponded to the peaks where hyaluronic acid binding region produced by CP and link protein migrate. Metalloenzyme inhibitors inhibited CMP with IC₅₀s of 5 × 10⁻⁵ M, 1 X 10⁻³ M, and 80μg/ml for phenanthroline, EDTA, and α2-macroglobulin, respectively.

Key Words:

• Proteoglycan degradation
• clostripain
• metalloprotease
• chondrocytes
• interleukin-1