Recent Advances in Aqueous Gel Permeation Chromatography

Peptide chemistry: development of high performance liquid chromatography and capillary zone electrophoresis

The development of relatively non-compressible supporting media of small particle size as well as pumps that deliver constant flow rates at high pressures has enabled investigators to perform rapid, high resolution liquid chromatography for more than two decades. Studies initiated in this laboratory in 1975, evaluating the compatibility of unprotected peptides with commercially available chromatographic supports and development of solvent systems ultimately led to separations not previously observed with both synthetic peptides and native peptides from tissue extracts. It was rapidly realized however, that recovery of certain molecules could be problematic. To meet the challenges presented by the isolation of natural hormones (such as corticotropin releasing factor and growth hormone releasing hormone) and proteins (such as inhibin and activin) and the need for large quantities of highly purified peptides for clinical investigations, our group invested heavily in identifying new supports (high carbon loading and 300 A pore sizes) and solvent systems (triethylammonium phosphate and trifluoroacetic acid) compatible with reverse phase, size exclusion and ion exchange chromatographies from a practical and economical perspective. More recently, we have contributed to the identification of unusual buffer systems (inclusive of organic modifiers) compatible with capillary zone electrophoresis that will both modulate the capillaries' selectivity, increase resolution and serve as an orthogonal approach to determining peptide purity. From a pragmatic point of view, in this paper we highlight the original and timely contributions (technical and strategical) of this laboratory in the field of analytical and preparative high performance liquid chromatography and capillary zone electrophoresis of synthetic and native biologically active peptides and proteins over the past twenty years.

Separation of cytochromes c by reversed-phase high-performance liquid chromatography

Six kinds of cytochrome c of different origin, i.e., bovine, chicken, dog, horse, rabbit and tuna, were subjected to separation by reversed-phase high-performance liquid chromatography on three commercial packing materials; octadecyl-, octyl- and cyanoalkyl-silicas. The effects of reversed-phase material, mobile phase and temperature on the separation of cytochromes c were examined. The parameters of the mobile phase were the organic modifier, the pH, the salt concentration and additives. Under optimal conditions, five of the six cytochromes c were resolved in 10 min. The relative retention values cannot be explained in terms of the relative lipophilicities of the side-chains of the amino acid residues.