The serine proteinase inhibitory proteins of the chondrodystrophoid (beagle) and non-chondrodystrophoid (greyhound) canine intervertebral disc

Trypsin inhibitory proteins of low buoyant density (p less than or equal to 1.35 g/mL) fractions were prepared by CsCl density gradient ultracentrifugation of 4 M guanidinium hydrochloride extracts of lumbar beagle and greyhound annulus fibrosus and nucleus pulposus from animals aged 1 to 6 years. Affinity blotting with biotinylated trypsin was used to identify active trypsin inhibitory protein species; these species were also identified immunologically by Western blotting using antibodies against bovine pancreatic trypsin inhibitor (BPTI), and human inter-alpha-trypsin inhibitor (ITI). None of the trypsin inhibitory species evident in Western blots were reactive with anti-human alpha(1)-proteinase inhibitor (alpha-(1)-PI), alpha(2)-macroglobulin or secretory leucocyte proteinase inhibitor. The greyhound intervertebral disc samples generally had higher levels of active trypsin inhibitor species per unit weight of tissue extracted, and a more extensive range of inhibitor species. Inhibitor species of 30, 32, 34 kDa were identified in both beagle and greyhound intervertebral disc samples; these species were generally most prominent in the annulus fibrosus samples. In contrast, the nucleus pulposus samples contained relatively large trypsin inhibitor species; the anti-BPTI detected an inhibitor species of similar to 85-90 kDa; anti-ITI detected species of 120-250 kDa; biotinylated trypsin detected species of 60-110 kDa. A small molecular mass trypsin inhibitor species of 6 kDa, which was of similar mobility to BPTI, was also detected in annulus fibrosus samples; however, this species did not react with anti-BPTI.