Catalase

I.U.B.: 1.11.1.6
H₂O₂:H₂O₂ oxidoreductase

Catalase catalyzes the following reaction:

Catalytic activity is present in nearly all animal cells and organs and in aerobic microorganisms. Studies on its biosynthesis have been reported by Higashi et al. (1974), Sakamoto and Higashi (1974) and Yasukochi et al. (1974). Yeast catalase has been characterized by Seah and Kaplan (1973) and Seah et al. (1973). It has recently been reviewed by Masters s, Pegg, and Crane (1986).

Like peroxidase it is a hemoprotein and forms intermediate addition compounds with H₂O₂. The stepwise mechanism of its activity was first elucidated by Chance (1951). See also Oshino et al. (1975), Zidoni and Kremer (1974), Chance and Oshino (1973), Chance et al. (1973), Jones (1973), and Jones and Middlemiss (1972). Nichols and Schonbaum (1963) have reviewed catalase.

Catalase uses H₂O₂ as a substrate as well as a hydrogen acceptor. Peroxidase requires a separate acceptor. Lanir and Schejter (1975) have reported on the difference in reactivity of the two enzymes. Nelson and Kiesow (1972) have studied the enthalpy of the catalase reaction. Corrall et al. (1974) and Oshino et al. (1973) report on the oxidation of ethanol and Marklund (1972) on its interaction with hydroxymethylhydroperoxide.

Catalase is of interest commercially wherever hydrogen peroxide is used as a germicide, for example, in the food industry for disposing of H₂O₂ used in pasteurizing milk prior to cheese-making (Chu et al. 1975). Microencapsulated catalase is also of interest (Poznansky and Chang 1974).

Characteristics of Catalase from Bovine Liver:

Molecular weight: 250,000 (Kiseler et al. 1967).

Composition: Sund et al. (1967) indicate 4 subunits of equal size (MW 60,000-65,000) in agreement with Shpitzberg cited by Kiseler et al. (1967). See also Furuta et al. (1974) and McPherson and Rich (1973). Fita and Rossmann (1985) and Kirkman and Gaetani (1984) report on the NADPH content. Mouse, rat and rabbit catalase show an isoenzyme pattern possibly due to two types of subunit. [(Jones and Masters (1975), Holmes (1972), and Holmes and Master (1972).]

An x-ray diffraction investigation and its comparison with an electron microscopy study has been reported by Rossmann and Labaw (1967). The amino acid sequence has been determined by Schroeder et al. (1969). Chemical modification of the enzyme has been reported by Abe et al. (1973).

Optimum pH: Approximately 7.0 (Maehly and Chance 1954).

Isoelectric point: pH 5.4 (Samejima et al. 1962).

Inhibitors: Inhibition by ascorbate alone as well as with Cu²⁺ has been shown by Orr (1967a and b). Freezing and lyophilization cause inactivation (Tanford and Lovrien 1962; Deisseroth and Dounce 1967). Mitchell and Anderson (1965) indicate catalases to be inactivated by sunlight under aerobic conditions. Catalase inactivation by peroxide has been reported on by Altomare et al. (1974).

Activators: No activators or cofactors are necessary.

Stability: All preparations are stable for 6-12 months when stored at 5°C. Do not freeze liquid preparations.