ELECTROMIGRATION BEHAVIOR OF POLY-(L-GLUTAMATE) CONFORMERS IN CONCENTRATED POLYACRYLAMIDE GELS

During electrophoretic separation of anionic polyamino acids, resoluti on according to the number of peptide units can be achieved in capilla ries filled with hydrophilic gels. While polyaspartate preparations yi eld single peaks for the individual oligomers at pH above 8.0, polyglu tamates exhibit an anomalous behavior of peak splitting, which is attr ibuted here to the separation of the oligopeptide conformers. An Asp-G lu (1:1) copolymer yields single peaks under similar conditions. At pH near 4.5, where polyglutamate is expected to exist in its alpha-helix form, peak splitting disappears. Upon heating to 95-degrees-C for at least 120 h (procedure described to transform the alpha-helix into a b eta form), peak splitting disappeared, but could be reestablished afte r cooling for several days. When a highly charged cation spermine was added to the operational electrolyte, triple peaks appeared in the ele ctropherogram due to the ion-pair formation. The largest peak in every triplet has been tentatively assigned to the alpha-helix form. The el ectrophoretic results described have been largely supported by CD spec tra. (C) 1993 John Wiley & Sons, Inc.