Autodegradation of the extracellular proteases of Brevibacterium linens ATCC 9172

Brevibacterium linens ATCC 9172 produces multiple forms of extracellular proteolytic enzymes as shown by polyacrylamide gel electrophoresis (PAGE) and activity staining. Four main bands with strong proteolytic activity, showing proteins with molecular weights of 280, 220, 130 and 43 kDa, were distinguished from several bands of lower activity. The formation of smaller entities on incubation at 38°C from the isolated main species of proteases was demonstrated, showing specific sequences in autodegradation. The cell wall-associated proteases were completely released by incubation of the cells at 50°C for 2 h and showed a similar isoenzyme pattern. There is evidence that the multiplicity of proteases is a result of aggregation from subunits and of autocatalytic degradation. The enzymes were identified as serine proteases by specific inhibition.