IR, MS and CD Investigations on Several Conformationally-Different Histidine Peptides

Solid phase synthetic methodology has been used to prepare four peptides which form a system able to monitor metal ion binding to conformationally different peptides. The 19-residues oligopeptides containing histidine residues in various positions of Ala or Gly sequences, namely GGGGHGGGGHGGGGHGGGG, GGGHGGGHGGGHGGGGGGG, AAAAHAAAAHAAAA-HAAAA, and AAAHAAAHAAAHAAAAAAA have been synthesized by Fmoc strategy and characterized by Fourier transform infrared spectroscopy (FT-IR) as well as electrospray ion trap mass spectrometry (ESI-MS) and circular dichroism (CD). The analysis of CD-spectra of the four peptides revealed that the secondary structure depends much on the amino acid sequence. Biological and medical consequences of conformational changes of metal-bound peptides are further discussed.