Comparison of catalase in diploid and haploid Rana rugosa using heat and chemical inactivation techniques

The present study examines differences in the hydrogen peroxide (H₂O₂) detoxifying enzyme, catalase, found in the tails and livers of diploid and haploid Rana rugosa. Investigative techniques include measurement of catalase activity and tests for temperature stability and chemical inhibition. Catalase from the tails of pre-climactic (stage XXIII) haploids was found to be over three times as H₂O₂ destructive as catalase from similar tails of diploids. Catalase from the livers of newly metamorphosed (stage XXV) froglets, on the other hand, displayed only one third the activity seen in diploid livers. The catalase in haploid tail and liver proved to be more heat resistant, retaining 40-60% of its original activity after 5 min of treatment at 55°C, whereas diploid catalase was totally inactivated under the same conditions. Haploid and diploid catalase also responded differently to inhibition using urea and aminotriazole. These differences suggest that haploid catalase has diverged from normal diploid catalase through molecular modification, resulting in abnormal systems for H₂O₂ metabolism, which in turn are thought to be responsible for organ dysfunction and early death seen in haploid individuals.