One-Dimensional Capillary Electrophoresis for Protein Analysis

Jorgenson reported the use of glass capillaries for free solution electrophoresis 25 years ago (Jorgenson andLukacs, 1981,1983). Aplug of analyte was introduced into a buffer-filled capillary and separated at high electric fields. Capillaries of 75 im inner diameter were employed, and detection of labeled amino acids and peptides was based on fluorescence. 

Both Reynolds and Karim worked at neutral pH, with denatured proteins, and with reduced disulfide bonds. Under these conditions, proteins are in a random coil conformation (Mattice et al., 1976), so that their hydrodynamic radius is monotoni-cally related to their molar mass. Takagi et al. (1975) reported that the binding isotherm of SDS to proteins strongly depends upon the method of denaturing disulfide bonds. Presumably, protein-SDS complexes are not fully unfolded when disulfide bonds are left intact, which breaks the relationship between molar mass and hydrodynamic 

Gelamo and Tabak (2000) reported a dramatic decrease in the binding of SDS to reduced bovine serum albumin at pH 9.0 compared to pH 7.0. However, this phenomenon is expected only if disulfide bonds are reduced there is little difference in the charge of the protein at these two pHs if the disulfide bonds are intact. 

2 Capillary SDS-Sieving Electrophoresis In the presence of a sieving matrix, mobility decreases monotonically with molecular weight for SDS-complexed proteins. This relationship is the basis of SDS-PAGE separation of proteins. 

Hj erten (1983) reported the use of crosslinked polyacrylamide gels for the capillary electrophoretic separation of proteins. However, crosslinked polymers are quite rigid, and the capillary has a short lifetime. 

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