INSIGHTS FROM A NEW ANALYTICAL ELECTROPHORESIS APPARATUS

Charge is a fundamental property of macromolecules that is inextricabl y linked to their structure, solubility, stability, and interactions. Progress has been made on the theoretical and structural aspects of th ese relationships. However, for several reasons, charge is difficult t o measure in solution. Consequently, there is a lack of experimental d ata that, independent of other macro-ion properties, determines the ef fective charge. To overcome this problem, novel instrumentation and me thods are being developed in our laboratory. Described here is an anal ytical electrophoresis apparatus that permits both the measurement of electrophoretic mobilities and the determination of steady-state elect rophoresis concentration distributions. The latter provides a differen t perspective on the processes that influence macro-ion behavior in an electric field. In addition, the apparatus permits the determination of diffusion coefficients either from boundary spreading during transp ort dr from the decay of a concentration gradient. All of these determ inations can be made with a single, 8-mu L sample in a variety of solv ents, thus providing unique insights into the charge properties of a m acro-ion. Presented here is a progress report about this emerging tech nology, including the description of a prototype apparatus and example s of its use with a DNA oligonucleotide.