Studies on the modulation of catalase activity in mammalian cell culture

Abstract

1. 1. The specific activity of catalase (H 2O 2:H 2O 2 oxidoreductase, EC 1.11.1.6) in suspension cultures of a cell line established from a hamster carcinoma has been shown to undergo temporal variation over a two-fold range which repeats itself from one growth cycle to the next upon serial propagation of this cell in vitro. The characteristic pattern of modulation observed could be modified by aeration which also promoted at least a further two-fold increase in maximum activity of this enzyme. Maintenance of the culture medium at pH 7.2 throughout the entire growth cycle had no effect on the pattern of fluctuation but decreased the enzyme activity by 20 to 30 per cent. Catalase levels of this cell line could not be influenced by the addition of iron, manganese, or hemin. An entirely different cycle of variation was observed for this enzyme with extracts of the L-cell. No ininfluence of aeration was apparent on the activity of catalase in this cell line. 2. 2. The quantitative fluctuation in enzyme activity from one phase of growth to the next is assumed to reflect the response of the autogenous regulatory process of the cell to the changing environment. This phenomenon is discussed as a potentially useful tool for the description of essential metabolic processes throughout the growth cycle and may serve to distinguish one cell type from another in vitro. It may serve also in the study of regulatory mechanisms operative in cells during the process of differentiation.