Abstract
Measurements of electrophoretic mobilities have contributed much to our understanding of the nature of proteins and other biologically important substances. The techniques usually employed, however, make use of optical methods and require a large amount os substances. so that the method cannot at present be generally used.
In this paper an attempt is described to determine electrophoretic mobilities at low concentrations. Mobilities can be caluculated by determining average concentrations of solute in upper (ascending) and lower (descending) limbs by appropriate analytical methods after the isolation of the four sections of ordinary Tiselius-type electrophoretic cell.
Mobilities of desoxypentose nucleic acid of herring sperm were measured in phosphate buffer at pH 7.7 and ionic strength 0.2 in concentration range 0.5-0.005% by measuring ultraviolet absorption at 258mμ and found to be about -16×10-5cm2/sec. volt, which agrees very well with those obtained by an optical method. In the case of E. coli bacteriophages T3 and T4, measurements were made at concentrations of about 107-108 phages/cc (about 10-6%) by determining the number of phages by a plaque method and found to be about -5×10-5cm2/sec. volt.
It may be concluded that this method is very useful especially in biological studies, though the errors are still larger in these experiments than in the usual optical electrophoretic measurements.
