Protein focusing in a conductivity gradient.
Conductivity gradient focusing (CGF) is one member of a family of gradient focusing techniques, characterized by two opposing forces which produce a dynamic equilibrium and which are able to simultaneously separate and concentrate proteins. In CGF, the two counteracting forces result from a constant convective flow of buffer opposed by an electric field gradient. This gradient in the electric field is formed by gradually decreasing buffer conductivity, i.e., when a slow-moving, relatively high conductivity buffer is dialyzed against a low conductivity purge buffer. This paper presents the design of an analytical-scale CGF device and the results of several experiments with colored proteins, both in free solution and with the use of a 45 micron size-exclusion (SEC) packing to decrease dispersion. Experimental results with hemoglobin suggest that CGF may one day be capable of resolving proteins with small charge differences. A linear computer model of conductivity gradient focusing is derived, and some suggestions are made for further development of this new electrophoretic method.
Greenlee
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RD
Department of Chemical Engineering, Washington State University, Pullman, Washington 99164-2710, USA.
Ivory
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CF
D002021:Buffers; D002845:Chromatography; D004058:Diffusion; D004553:Electric Conductivity; D004574:Electromagnetic Fields; D007525:Isoelectric Focusing; D016014:Linear Models; D008567:Membranes, Artificial; D011506:Proteins / Q000302:isolation & purification*
D002021:Buffers; D008567:Membranes, Artificial; D011506:Proteins