EFFECT OF MOBILE-PHASE ON THE OLIGOMERIZATION STATE OF ALPHA-HELICAL COILED-COIL PEPTIDES DURING HIGH-PERFORMANCE SIZE-EXCLUSION CHROMATOGRAPHY

Important structural motifs involving amphipathic helices include two- stranded and multiple-stranded coiled-coils. High-performance size-exc lusion chromatography (HPSEC) is a useful tool to examine both the oli gomerization state of coiled-coils as well as the stability of such mo tifs, due to the facile manipulation of the mobile phase and the lack of interaction of the peptide solutes with the stationary phase. In th e present study, HPSEC was applied to two series of de novo designed m odel amphipathic alpha-helical peptides with the sequences (1) Ac-(E-A -L-K-A-E-I)(n)-E-A-C-K-A-amide, where n=1 or 3, Ac-E-I-(E-A-L-K-A-E-I) (4)-E-A-C-K-A-amide and (2) Ac-(K-L-E-A-L-E-A)(n)-amide, where n=1, 2 or 4. Observation of the retention behaviour of Series 1 under both de naturing and non-denaturing conditions at pH 7.0 offered insights into the effect of polypeptide chain length and disulphide bridge formatio n on the stability of alpha-helical coiled-coils. In contrast, the Ser ies 2 peptides showed promise as peptide standards to monitor the effe ct of environment on the multi-strandedness of coiled-coils, since the 28-residue peptide of this series was eluted as a monomer, dimer or t rimer depending on mobile phase conditions. (C) 1997 Elsevier Science B.V.