Supernatants from cultures of contained up to 10 components with CM-cellulase activity as determined by non-denaturing PAGE. Some of the active components were glycosylated. The activity profiles of the supernatants, as determined by PAGE, varied with the cellulosic substrate used for the growth of a culture, with culture age, and with storage of the supernatants. These variations were a consequence of proteolysis and a reduction in the glycosylation of some of the components. Proteinase activity in the supernatants was induced by growth of on cellulosic substrates. Proteolysis and a reduction in glycosylation resulted in the conversion of slow-moving into fast-moving components on non-denaturing PAGE. The fast-moving components had a reduced ability to bind to an insoluble cellulosic substrate such as Avicel. Several of the CM-cellulase activities in culture supernatants were immunologically related. In contrast to the large number of CM-cellulases found in the supernatant, substrate-bound activity comprised only three slow-moving components, at least some of which were glycosylated. It was concluded that the cellulase system of was composed of only three enzymes, and that these enzymes had a great affinity for, and were stabilized by binding to, an insoluble cellulosic substrate. Enzymes which accumulated free in the culture medium were subject to limited proteolysis and de-glycosylation which generated a variety of products, some of which retained enzymic activity.


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