The degradation of type I collagen and human plasma fibronectin by the trypsin-like enzyme and extracellular membrane vesicles of Bacteroides gingivalis W50.

A soluble trypsin-like enzyme (STE) was purified from a cell- and particle-free culture supernatant of this bacterium by a combination of ultra-centrifugation, ammonium-sulphate precipitation and gel-filtration chromatography on Sephacryl S-200. Trypsin-like activity in the culture supernatant was associated with a 58 kDa peptide and also with a higher molecular-weight complex. The STE and extracellular vesicle (ECV) fraction of B. gingivalis W50 rapidly degraded human plasma fibronectin in the presence and the absence of 10 mM dithiothreitol (DTT). The STE yielded a range of lower molecular-weight fibronectin digestion products. Under conditions where little activity was expressed by mammalian trypsin, both STE and ECV depolymerized a denatured and a native type I collagen substrate. Quantitative and qualitative differences were observed in the patterns of digestion products generated by both STE and ECV fraction following incubation with and without 10mM DTT. Inclusion of DTT appeared to reduce the degradative effect of both ECV and STE towards the type I collagen and plasma fibronectin substrates.