Heterogeneity of Crystalline Rennin

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Abstract
Block-shaped crystals were prepared from a concentrated solution of purified rennin by dialyzing it against Berridge''s salting-in buffer. The purification procedure was relatively simple, and proved successful in each of several attempts to obtain rennin pure enough to crystallize. A single boundary in electrophoresis represented over 96% of the protein when a 0.6% solution of the crystalline enzyme was run at pH 6.8 in sodium phosphate buffer at an ionic strength of 0.2. However, at least 4 components were indicated in the electrophoretic patterns when run in the same buffer at 0.033 ionic strength and 0.7% protein concentration. Results show that rennin preparations cannot be considered homogeneous on the basis of their crystalline form or their electrophoretic behavior in phosphate buffers of high ionic strength.