Due to its high resolving power while retaining the native state, IEF is preferably used for the characterization of complex protein mixtures, particularly, if their components are almost indistinguishable, for example the isoforms of certain enzymes. Here, using »ultrathin« slab gels (0.5 mm or thinner) extremely high resolution can be obtained.
In routine analysis, precast gels with carrier ampholytes or with immobilized pH gradient are available to save time and effort and to provide reproducible, reliable results.
To determine the isoelectric points of unknown proteins the pH of focused bands may be measured on the gel using a surface electrode. Quite common is the pI determination via coelectrophoresis of known protein marker mixtures. By simply comparing the position of unknown protein bands to the position of known marker proteins the pI values can be interpolated quite accurately.
- ready-to-use protein markers for isoelectric focusing
- one standard applicable to all IEF gels (vertical/horizontal)
- purified protein components, salt-free
- 13 isoforms featuring characteristic patterns
- for determination of pI of unknown protein samples
- for monitoring the separation performance of IEF gels