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Effect of pH and Sodium Chloride on Activation of Prorennin^{1, 2,}

Department of Dairy and Food Industries, University of Wisconsin, Madison

ABSTRACT

Prorennin was extracted from calf-stomach tissue and purified by a modification of Foltmann's procedure. Both pH and salt (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 M 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.

Activation of prorennin at pH 5.0 and 4.7 was predominantly autocatalytic, but there was evidence of a limited nonautocatalytic 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.

¹ Published with the approval of the Director, Wisconsin Agricultural Experiment Station.

² This study was supported in part by a research grant from the Research Committee of the Graduate School, University of Wisconsin, from funds supplied by the Wisconsin Alumni Research Foundation.

³ Present address: Department of Animal and Dairy Science, University of Rhode Island, Kingston, Rhode Island.