Low molecular weight serine proteinase inhibitors of human articular cartilage. Isolation, characterization, and biosynthesis.

The major low molecular weight serine proteinase inhibitor of human articular cartilage was purified to homogeneity as determined by single-peak elution with 4 high resolution techniques. The purified protein was found to be a potent inhibitor of human leukocyte elastase and cathepsin G, as well as the native serine proteinases derived from human articular cartilage and intervertebral disc. The inhibitor and lysozymes were synthesized by human articular cartilage in vitro. These properties and the ability of this cationic inhibitor to bind to cartilage matrix components suggest a possible role in the modulation of matrix catabolism in normal and pathologic states.