Distinctive properties of the catalase B of Aspergillus nidulans

Aspergillus nidulans catalase B (CatB) was purified to homogeneity and char acterized as a hydroperoxidase which resembles typical catalases in some ph ysicochemical characteristics: (1) it has an apparent molecular weight of 3 60 000 and is composed of four glycosylated subunits, (2) it has hydrophobi c properties as revealed by extractability in ethanol/chloroform and bindin g to phenyl-Superose, and (3) it has an acidic isoelectric point at pH 3.5. Also CatB exhibits some distinctive properties, e.g. it is not inhibited b y the presence of 2% sodium dodecyl sulfate, 9 M urea or reducing agents. F urthermore, even though CatB does not exhibit any residual peroxidase activ ity, it is able to retain up to 38% of its initial catalase activity after incubation with the typical catalase inhibitor 3-amino-1,2,4-triazole, (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Sc ience B.V. All rights reserved.