Purification and properties of proteases produced by Alternaria alternata (Fr.) Keissl, regulation of production by fructose

A strain of Alternaria alternata (Fr.) Keissl, when grown on wheat bran Czapek Dox medium was found to secrete one neutral and two alkaline proteases. The purified enzymes were found to be endo peptidases, the alkaline proteases being serine proteases and neutral proteases being cysteine proteases. Fructose when added to the culture medium was found to give rise to a new neutral protease at the expense of the neutral protease produced in the absence of fructose and was also found to enhance the production of alkaline proteases. It also appears that fructose modifies the alkaline proteases with respect to some characteristics such as V sub(max), Ea etc. Sodium dodecyl sulphate polyacrylamide gel electrophoresis indicated a significantly altered protein profile in fructose supplemented medium.