The inhibitory protein of chitin synthetase from Mucor rouxii is a chitinase

The 'inhibitor' of chitin synthetase previously isolated from the cytosol of Mucor rouxii was found to be a chitinase. Paper chromatographic analysis of reaction products showed that the overall rate of chitin synthesis was unaffected by the 'inhibitor'. The observed reduction in chitin synthesis was due to depolymerization of chitin, mostly dimers (diacetyl-N,N'chitobiose). The chitinase was much more effective against nascent chitin, i.e., chitin being made in a chitin synthetase incubation mixture, than against preformed chitin.