Synthesis, crystal structure, and coordination properties of a helical peptide having β-(3-pyridyl)- l-alanine and l-glutamic acid residues

Abstract

A novel helical peptide containing β-(3-pyirdyl)- l-alanine (Pal) and l-glutamic acid (Glu) residues has been designed and successfully prepared as a model ligand of metalloenzyme active sites. The helical peptide, Boc-Leu-Aib-Glu-Leu-Leu-Pal-Aib-Leu-OEt ( 1) (Boc = tert-butoxycarbonyl, Aib = 2-aminoisobutylic acid) yields fine crystals as an acetnitrile solvate. The metal ion binding affinities of 1 were tested for CoCl 2 using UV/vis, CD, Raman, and 1H NMR spectroscopies. The non-linear fitting calculations have revealed the 1:1 complex for CoCl 2 with the binding constant 3.6 (±0.7) × 10 2 M −1.