Cleavage of collagen type X by human synovial collagenase and neutrophil elastase

Chick-derived native cartilage collagen type X and the pepsin-resistant 45 kDa fragment were susceptible to attack by human synovial collagenase and neutrophil elastase at 25 degrees C and 35 degrees C. Synovial collagenase cleaved type X collagen at two sites which were equally susceptible to the enzyme. In contrast, elastase produced three cleavages, but the sensitive loci showed different susceptibilities as judged by the sequential appearance of specific breakdown products. Both enzymes produced a major, enzyme-resistant fragment of approximately 32 kDa at 35 degrees C, and both of these end-products co-migrated in SDS polyacrylamide gels. Human chondrocyte-derived collagenase also degraded native, 59 kDa collagen type X in a similar manner to that shown by the synovial collagenase. From amino acid sequence data the enzyme cleavages probably occur at three regions of sequence imperfection. The specific cleavages brought about by synovial or chondrocyte collagenase, or neutrophil elastase, may have a functional catabolic role in vivo, and in vitro might provide useful tools with which to further analyse specific properties of the native collagen type X molecule.