Capillary electrophoresis of peptides and proteins in isoelectric buffers:An update

Capillary electrophoresis in acidic, isoelectric buffers is a novel methodo logy allowing fast protein and peptide analysis in uncoated capillaries. Du e to the low pH adopted and to the use of dynamic coating with cellulose de rivatives, silanol ionization is essentially suppressed and little interact ion of macromolecules with the untreated wall occurs. In addition, due to t he low conductivity of quasi-stationary, isoelectric buffers, high-voltage gradients can be applied (up to 800 V/cm) permitting fast peptide analysis with a high resolving power due to minimal diffusional peak spreading. Four such buffers are here described: cysteic acid (Cys-A, p/1.85), iminodiacet ic acid (IDA, p/2.23), aspartic acid (Asp, p/2.77) and glutamic acid (Glu, p/3.22). A number of applications are reported, ranging from food analysis to the study of folding/unfolding transitions of proteins.