Effect of pH and Sodium Chloride on Activation of Prorennin

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Abstract
Prorennin was extracted from calf-stomach tissue and purified by a modification of Foltmann''s procedure. Both pH and NaCl concentration were shown to have considerable effect on the rate of activation of prorennin as well as the final yield of activity. Greatest yields of stable activity were obtained by activating at pH 5.0 in the presence of 1.5 - 2.0 [image] NaCl. At lower pH values activation was more rapid, but the activated enzyme was less stable. Activation at pH 2.0 - 4.0 was extremely rapid and gave high yields of activity which quickly deteriorated. Also the presence of any amount of NaCl in that pH range inhibited activation and reduced yields; the greater the salt concentration, the greater the effect. The activation of prorennin at pH 5.0 and 4.7 was predominantly autocatalytic, but there was evidence of a limited non-autocatalytic activation that occurred before autocatalysis became predominant. Activation at pH 2.0 was very rapid, even at low temperatures, and the kinetics under these conditions could not be followed with any degree of accuracy.