Sodium dodecyl sulfate-gel electrophoresis of proteins employing short capillaries.

The performance of capillary gel-sodium dodecyl sulfate (SDS) electrophoresis for molecular-mass-dependent separation of proteins has been examined employing cross-linked polyacrylamide gels and untreated fused-silica capillaries of short length. An apparatus for capillary electrophoresis has been constructed, combining a UV detector equipped with a capillary holder, a power supply, and a micromanipulator for sample loading. The apparatus is capable of accommodating gel capillaries of different lengths and can be operated with two methods of sample loading: manual injection on top of the gel or electrokinetic injection. Standard proteins have been separated according to their molecular mass (ranging from 17000 to 116000) within 30 min, employing gel capillaries of effective lengths shorter than 10 cm and polyacrylamide gels ranging from 2.4 to 4.8%T (5%C). The results confirmed that gel capillaries of effective length less than 10 cm can be used for protein size-separation by SDS electrophoresis, with much higher performance than is achieved in rod gel-SDS electrophoresis.