Heterogeneity of Crystalline Rennin

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 the dissolved crystals were run at pH 6.8 in sodium phosphate buffer at an ionic strength of 0.2. However, at least four components were evident in the same buffer at 0.033 ionic strength. These results show that rennin preparations can not be considered homogeneous on the basis of their crystalline form or their electrophoretic behavior in phosphate buffers of high ionic strength.