Influence of protein concentration upon electrophoretic mobility of serum proteins.

Previous investigators have reported a change in distribution of serum protein fractions, as measured by the areas subtending the conventional electrophoresis curves, as a result of a change in ionic strength of the buffer (1) or as a result of a change in total protein concentration (1, 2). A similar effect of total protein concentration on the electrophoretic analysis of ovalbumin has been shown by Cann (3). Although the effects of buffer ionic strength, buffer species, and pH on mobility have been well known, little attention has been given to the effect of protein concentration and species on the electrophoretic mobility of proteins. Luetscher (4) suggested that mobility might increase with protein concentration, but this comment was not amplified. Longsworth and MacInnes (5), in a discussion of electrophoresis patterns, presented a table which showed a decrease in the mobility of ovalbumin with increased protein concentration. Alexander and Johnson (6) refer to an unpublished qualitative observation (Johnson and Shooter, 1946) that protein mobility decreased with an increase in protein concentration. In a recent, paper on another subject, Alberty and Marvin (7) presented a table which showed a 10 per cent decrease in the mobility of bovine serum albumin at pH 7.0 as the protein concentration increased from 2 to 8 per cent. Our attention was called to this subject in the course of an experiment with rats which had been given nephrotoxic globulin to produce experimental nephritis. Analysis of sera from these animals suggested an apparent relation between the mobility of serum albumin and severity of