Properties of a catalase from a peroxide-resistant mutant of Proteus mirabilis

Publisher Website
Google Scholar
Abstract
A catalase (EC 1.11.1.6) from P. mirabilis PR, a mutant with strong resistance to H2O2, was purified to homogeneity and compared with catalase from wild-type P. mirabilis. In crude extracts from the mutant, catalase was present as 2 different entities, A and B, that could be resolved by ion-exchange chromatography. The B form was transformed into A. The pure catalase preparation contained the A form only. This catalase did not differ from the wild-type enzyme in MW, subunit composition, isoelectric pH and reactivity to specific antibodies. Partial proteolytic cleavage of the 2 bacterial enzymes with 4 different proteases proceeded at the same rate and produced identical patterns. However, pure catalase from the mutant had a specific activity against H2O2 of 2.7 .times. 107 M-1 .cntdot. s-1 and its purity index was 1.12. These values were higher than those previously determined for the wild-type enzyme. The mutant catalase was more stable to heat. Thus the purified catalase (A form) differs from the wild-type enzyme and appears to be a more efficient catalase against H2O2. Both enzymes were much more resistant than beef liver catalase to the catalase inhibitor 3-amino-1,2,4-triazole.

This publication has 4 references indexed in Scilit: