Dynamics of protein isoelectric focusing in immobilized pH gradient gels

The protein migration velocity profile through the pH gradient in immobilized pH gradient gels (IPG) was investigated. Strong nonuniformities of migration velocity distribution, which could not be remedied by adding carrier ampholytes, were observed at the initial stages of a run (up to several thousand volt-hour products for wide pH gradients). The final (after a prerun) velocity distribution in IPG gels differs from the one containing carrier ampholytes, with maximum velocity being achieved not at the pH extremes but closer to neutrality. In some uniform pH media, created by either a single or by several Immobilines, essentially a nonconstant migration profile was also obtained immediately after a prerun. After a prerun, followed by a pause in the absence of current, the phenomenon of fast evolution of the final velocity profile was found.