Complexation of metal ions by pseudotripeptides with different functionalized N-alkyl residues

Abstract

Seven pseudotripeptides with the common structure Bz-His-Ψ[CO-N(CH₂)n-X]Gly-His-NH₂ were synthesized on the solid phase using the Fmoc-strategy, trityl protection for both His residues and Boc- or -OBu^t-protection for N-aminoalkyl- and N-carboxyalkyl residues, respectively. Functionalized N-alkyl glycyl peptides were formed on the solid phase by amination of a bromoacetyl dipeptide. All seven pseudotripeptides are able to form chelate complexes with the metal ions Zn²⁺, Ni²⁺, Cu²⁺ and Co²⁺. The existence of monomeric 1:1 complexes for these pseudopeptides was calculated from the MW estimated by MALDI-MS and from the isotope distribution pattern estimated by ESI.