Red blood cell enzymes in the black rhinoceros (Diceros bicornis): initial molecular studies of catalase

The enzyme catalase may play a pivotal role in the pathogenesis of acute episodic hemolysis in the black rhino. We constructed a black rhino fibroblast cDNA librray and screened for catalase sequences with a human catalase cDNA probe. The DNA sequence of a positive clone that represented 86% of the coding region of the catalase gene was determined. The translated amino acid sequence was 90-95% homologous to bovine, human, mouse and rat catalase sequences. A hypervariable region of 16 amino acids was only 37.5 % identical between black rhino and human sequences. This result may offer a possible explanation for the finding that catalase activity in black rhino erythrocytes is only 2-3% of that found in human erythrocytes.