Properties of azide-catalase

Abstract

It is now well established that catalase is a conjugated protein with protohaematin as its prosthetic or active group. Catalase resembles acid methaemoglobin in its colour, its absorption spectrum, and above all in its property of combining reversibly and forming well-defined derivatives with HCN, H2S, HN3, HF, N1I20H, NO and C2H0. OH. However, it differs from methaemoglobin in three important properties, namely: (1) the colour and absorption spectrum of its compound with azide (NaN3), (2) the reaction with H202, which consists in a violent, almost explosive, decomposition of the latter, during which it is impossible to observe any changes in colour and absorption spectrum of the enzyme, and (3) the stability of its trivalent iron which is not reduced even by Na2S204. In this latter respect catalase differs fundamentally from all other haematin derivatives (Keilin & Hartree,1936).