The inhibition of catalase by plasma and by human tissue extracts

Abstract

1. 1. The catalase activity of dilutions of heparinised blood was consistently less than that of haemolysates of the same haemoglobin concentration, prepared from the same blood samples. 2. 2. The incubation of plasma with solutions of crystalline catalase led to a reduction in catalase activity; the inhibitory effect was removed by dialysis of the plasma. 3. 3. Catalase inhibition was observed, in varying degree, with all samples of plasma from normal subjects and from patients with different disorders, including neoplastic disease. No relationship was observed between the clinical diagnosis and the degree of inhibition produced by the plasma. 4. 4. The inhibition of catalase produced by incubation with plasma was increased by the addition to the incubation mixture of 3-amino-1,2,4-triazole (AT), and was reduced by the addition of EDTA or - N-ethyl-maleimide. 5. 5. The degree of inhibition produced by plasma was related to the ascorbic acid concentration in the plasma, although this substance could not account for all the inhibitory effect. 6. 6. Boiled aqueous extracts of liver and kidney were prepared from tissues obtained at post-mortem examination. On incubation with haemolysates, and with solutions of crystalline catalase, inhibition of catalase activity was produced by extracts of liver, and to a less extent by extracts of kidney. There was no difference in the inhibition produced by extracts of tissues from subjects with or without neoplastic disease.