Initial studies with a brain catalese

Abstract

Initial experiments with crude beef brain catalase showed that optimal activity occurred at pH 8.5 in contrast to pH 6.8 for beef liver and red blood cell catalase. Lowest activity occurred at pH 4.6 in all cases. A 200- to 300-fold purification of brain catalase was achieved but produced only a 2 to 3% yield. A comparative pH activity study of purified beef liver, red blood cell and brain catalases confirmed the findings of the crude extracts except that brain catalase was inactivated at pH 4.6. The overall reaction constant for the decomposition of hydrogen peroxide by brain catalase at pH 8.5 was calculated to be 4.56 × 10 6 M −1 sec −1. It is felt that this value may increase with further purification of the enzyme. The turnover number calculated for brain catalase was 4.5 million. The iron content of a sample of purified brain catalase was found to be 0.3%. Most known catalases contain between 0.09% and 0.1% iron per molecule of enzyme.