Peptide ionophores: synthesis and cation-binding properties of a bicyclic peptide containing glycine and lysine residues.
Peptide 1, cyclo(1,5-epsilon-succinoyl) (Lys-Gly-Gly-Gly)2, is a representative member of a family of polycyclic peptide ionophores characterized by C2 symmetry and a relatively flexible structure resulting from its high Gly content. Peptide 1 has been synthesized by two different solid-phase protocols from its linear precursors, H-Gly-Gly-Lys(Fmoc)-Gly-Gly-Gly-Lys(Fmoc)-Gly-OH and H-Gly-Gly-Lys(Z)-Gly-Gly-Gly-Lys(Z)-Gly-OH), and satisfactorily characterized by chemical means. The CD spectrum of 1 is compatible with a beta-folded structure, stabilized by two internal hydrogen bonds. The complexation behavior of 1 toward alkaline and alkaline-earth cations can be envisaged as an equilibrium between inclusion (1:1) and sandwich (2:1) complex models, with affinities in the 10(6) M-1 and 10(11) M-2 range, respectively. A slight preference of 1 for Sr2+ over other cations has been found.
Crusi
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University of Barcelona, Spain.
Giralt
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Andreu
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D
D000595:Amino Acid Sequence; D002412:Cations / Q000378:metabolism*; D002942:Circular Dichroism; D005998:Glycine / Q000737:chemistry; D007476:Ionophores / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D008239:Lysine / Q000737:chemistry; D008673:Metals, Alkaline Earth / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010456:Peptides, Cyclic / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D017510:Protein Folding; D017433:Protein Structure, Secondary; D013386:Succinates / Q000737:chemistry
D002412:Cations; D007476:Ionophores; D008673:Metals, Alkaline Earth; D010456:Peptides, Cyclic; D013386:Succinates; D008239:Lysine; D005998:Glycine