Role of Catalase in Biological Oxidation as Demonstrated by Proteus vulgaris

The research presented here is a contribution to the old problem of whether the ferment catalase is connected with the oxidative metabolism of the living cell. In the past, as here, such investigations have been carried out chiefly with bacteria. The many contradictory findings in the literature are doubtless explained by the fact that catalase was not known until recently to exist in two states, an active and inactive form. Previous workers have, therefore, been unable to obtain the total catalase of the cell, but only, as is shown here, a relatively insignificant fraction of it.In order to estimate the catalase content of bacteria it is, therefore, necessary to first change the inactive enzyme to the active form. This is done by treatment with an activator, an extract made from heart muscle. The reaction which takes place require a short but definite time and a temperature considerably above that at which the enzyme itself can act. The active and activated enzyme is, however, shown to be unstable, and decomposes quite rapidly.If the total catalase after activation be determined, as well as the number of bacteria present in an experiment, it is seen that the total per cell varies with the oxygen tension under which the organisms have been kept immediately before the experiment. An increase in oxygen tension causes up to a very high 02 concentration, an increase in total catalase, thus directly connecting the catalase with the oxygen supply of the bacteria, and indirectly connecting it with their oxidative metabolism, which naturally increases, at first at least, with increasing oxygen supply. This furnishes very good evidence for the view that catalase participates in biological oxidation.