Porcine thyroid cytosolic, latent, alkaline, ribonuclease: does an acidification step during purification alter the enzyme's properties?

The effect of an acidic step in the purification of porcine thyroid, latent, alkaline ribonuclease was studied using highly purified acid-treated and non-acid-treated enzymes. The enzymes differed by affinity and CM-cellulose chromatography, specific activity, in distribution among multiple forms, in response to some mono- and divalent salts, in degree of inhibition by p-chloromercuriphenylsulfonate and ribonuclease inhibitor, in activity toward poly (U). The acid-treated enzyme was very heterogeneous as shown by chromatography on affinity and ion-exchange columns and electrophoresis. The enzymes had similar molecular weights, pH optima, ionic strength effects, general specificity and products.