Alcohol precipitation of proteins: The relationship of denaturation and precipitation for catalase

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Abstract
The precipitation of crude beef liver catalase at 4°C by the lower alcohols could be correlated in a manner analogous to that used for salting out precipitations with ammonium sulfate. At high alcohol concentrations, however, the analogy breaks down since denaturation effects must betaken into account Depending upon the concentration of the alcohol and temperature, the denaturation transition may be either thermally induced or solvent induced. When the precipitated enzyme was redissolved in buffer, not all forms could refold spontaneously to a catalytically active conformation. The data on the precipitation yields of catalase correlated well with denaturation diagrams previously developed. Thus, a quantitative basis could be established to relate the sensitive performance of the technique to the experimental conditions. A further correlation between the amino‐acid composition of the enzyme and the optimal concentration of alcohol required for precipitation may provide a guide for the extension of this work to other systems.