Purification,partial N-terminal sequencing and properties of an endoglucanase from Aspergillus niger

A novel cellulase was identified and isolated from a commercial Aspergillus niger cellulase preparation.The crude enzyme preparation,which was prepared by precipitation of the water extract of the culture of Aspergillus niger with ammonium sulfate,was further fractionated by three steps of chromatography of weak anion exchange to obtain an electrophoretically homogeneous cellulase. The molecular weight of the purified enzyme was estimated by SDS-PAGE to be 36kD under non-reduced conditions and 38kD under reduced conditions, with the optimun pH at 3.5, and the optimum temperature at 55℃. The partial N-terminal amino acid sequences of the purified enzyme was identified as XXXFKCVGSMEDGAES.