THE INFLUENCE OF BUFFERS ON THE pH OPTIMUM OF ACONITASE

Abstract

Jaeobsohn (1941) found tliat the pH optimum of aeonitase in the presence of phosphate buffer was in tlie neutral region. A more extensive study of the influence of pH on aeonitase aetivity was made by Johnson (1939). He elaimed that the pH-activity curve showed a sharp maximum at pH 7-4, but this value must be regarded as approximate. The pH values chosen for testing the aeonitase aetivity were widely spaced, and no mention was made of the buffers used to cover tlie extensive pll range.The above information was gained from studies with crude aeonitase preparations. Aconitase has now been highly purified (Morrison 1954a) and shown to be dependent on the presence of Fe-" and a redueing agent for maximum aetivity (Dickman and Clouticr, 1951;Morrison, 1954a). A more detailed investigation of tlip effect of pll on the activated, purified enzyme showed that the pH optimum is dependent on the type of buffer used. For a preliminary report of this work, see Morrison (iy54b).