Extracellular Maltase from Aspergillus Flavus

SUMMARY

An extracellular maltase activity was induced in Aspergillus flavus during growth in liquid medium containing maltose as the sole carbon source. The enzyme was also detected in the mycelial extracts of the organism. Synthesis of this enzyme was repressed by the addition of glucose or lactose to maltose-metabolizing cells, and was induced in glucose- or lactose-containing cultures by addition of maltose. The enzyme was partially purified by ammonium sulphate precipitation followed by gel permeation and ion exchange chromatography. The purified enzyme has an approximate molecular weight of 63,000 Daltons and exhibited maximum activity at pH 6.0 and 35 C. Ion exchange chromatography resolved the enzyme complex into two components with apparent Km's of 10 mM and 29 mM, respectively, for maltose.