Immobilized pH gradients

In this short review, we give an account of the steps through which the protocols for operation with IPGs were set up in the early '80s. One of the main achievements by our group was the development of a computer program, pH GRADIENT, for the calculation of pH, buffering power and ionic strength of a mixture of monoprotic buffers titrated within any pH span and for the linearization of the desired pH gradient. Using this program, in 1984 we could devise formulations for IPGs covering up to six pH units, which was the subject of a publication in Electrophoresis (volume 5, pages 88-97). This was the starting point for the use of IPGs for the resolution of protein samples of any composition and for their application as first dimension of 2-DE separations. Currently IPGs are in common use in proteomics investigations, not only along classical protocols but also for sample prefractionation and in shotgun approaches. Much less frequently are they used for 1-DE analytical applications, a field for which in recent years much attention has instead more often focused on capillary electrophoresis/IEF procedures.