Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)


Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Food Science and Technology


C. A. Ernstrom


Purified prorennin appeared to be homogeneous when subjected to chromatography on a Diethylaminoethyl-cellulose and to electrophoreses in starch-urea-gel. Crystalline rennin was heterogeneous, and was resolved into six components when analyzed electrophoretically. When crystalline rennin was chromatographed on a column of Diethylaminoethyl-cellulose two distinguishable peaks were observed which corresponded to B- and C-rennin. Unlike crystalline rennin, rennin freshly activated at pH 2.0 or 5.0 was essentially homogeneous.

Rennin resulting from activation at pH 2.0 and 5.0 appeared to be different. Rennin activated at pH 5.0 was eluted faster from Diethylaminoethyl-cellulose column, and moved slightly faster in starch-urea-gel electrophoresis, than rennin activated at pH 2.0. Amino acid analysis showed that rennin activated at pH 2.0 had more arginine and less proline than that activated at pH 5.0. This could be accounted for the differences in chromatographic and electrophoretic behavior of these rennins.

Crystalline rennin exhibited more resistance to urea denaturation than prorennin. This suggested a fundamental difference in their secondary or (and) tertiary structures. It also showed the importance of intramolecular H-bonding for enzyme activity. An increase in crystalline rennin components was accompanied its prolonged exposure to 6 M urea. This was not the case with prorennin.



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