Selected buffer systems for moving boundary electrophoresis on gels at various pH values, presented in a simplified manner

Moving boundary electrophoresis on gels is useful for 4 purposes: (1) As an automatic concentration method to produce concentrated starting zones of proteins* for analytical and preparative resolving gels; (2) to provide a sharply defined reference zone in the resolving gel for Rf measurement; (3) for the preparative electrophoretic extraction of proteins from gel slices; (4) for high load preparative “charge fractionations” of relatively simple mixtures of proteins. It requires buffer systems at various pH values which are capable of setting up moving boundaries with numerically known leading and trailing ion mobilities. Moreover, since protein migration is slow compared with that of buffers, these moving boundaries have to have low displacement rates if they are to concentrate and align the proteins in order of mobility. Ten years ago, the authors made available in form first of magnetic tapes, then of microfiche, a collection of buffer systems for that purpose. But, in spite of the large number, over 4000, of these buffer systems, biochemists have not taken advantage of them widely. This appears in part due to the terminological complexity of the presentation needed to give an exhaustive physical‐chemical description of the systems. In part, it was due to the confusion about which of the various forms and techniques of moving boundary electrophoresis, known under a variety of names, these buffer systems applied to. Also, among the many buffer systems, only relatively few exhibited sufficiently low moving boundary displacement rates to allow slowly migrating proteins to migrate within the moving boundary. Finally, it proved difficult for potential users to interpret the magnetic tapes and microfiche; also tapes were excessively expensive. To remedy all these problems, and to allow biochemists to benefit more widely, both analytically and preparatively, from moving boundary electrophoresis at any pH, we have selected a small number of buffer systems capable of concentrating proteins within moving boundaries set up at various pH values, with low displacement rates, and with either anodic or cathodic displacement. These are presented in simplified format and terminology.