RESUMO
The fungus Penicillium purpurogenum produces several extracellular xylanases. The two major forms (xylanases A and B) have been purified and characterized. After ammonium sulfate precipitation and chromatography in Bio-Gel P 100, xylanase A was further purified by means of DEAE-cellulose, hydroxylapatite and CM-Sephadex, and xylanase B by DEAE-cellulose and CM-Sephadex. Both xylanases showed apparent homogeneity in SDS-polyacrylamide gel electrophoresis. Xylanase A (33 kDa) has an isoelectric point of 8.6, while xylanase B (23 kDa) is isoelectric at pH 5.9. Antisera against both enzymes do not cross-react. The amino terminal sequences of xylanases A and B show no homology. The results obtained suggest that the enzymes are produced by separate genes and they may perform different functions in xylan degradation.
