Interactions of α-Factor-1, a Yeast Pheromone, and Its Analogue with Copper(II) Ions and Low-Molecular-Weight Ligands Yield Very Stable Complexes

Abstract

α-Factor-1 (WHWLQLKPGQPMY), a peptidic pheromone of Saccharomyces cerevisiae yeast, contains a XHX type copper(II) binding N-terminal site. Using a soluble analogue, WHWSKNR-amide, we demonstrated that the W(1)H(2)W(3) site alone binds copper(II) with a Kd value of 0.18 pM at pH 7.4 and also binds imidazole (Im) in a ternary complex (Kd of 1 mM at pH 7.4). This interaction boosts the ability of the peptide to sequester copper(II) depending on the Im concentration up to a subfemtomolar range, not available for any oligopeptidic system studied before. Therefore, α-factor-1 and other XHX-type peptides are likely copper(II) carriers in biological systems.

Ternary Cu(II) Complex with GHK Peptide and Cis-Urocanic Acid as a Potential Physiologically Functional Copper Chelate

“…Such complex corresponds to CuH 2 (GHK) 2 stoichiometry. However, the observed changes in the electronic spectra are very similar to those seen previously in ternary complexes of other Xaa-His peptides (where Xaa is any amino acid residue except Pro) with imidazole (3+1N coordination, where three nitrogen atoms, NH 3 + (N-term) , N amide , and N Im , are from the first peptide molecule, and one nitrogen atom is N Im from the second peptide molecule) [ 20 , 21 ]. Therefore, we assign the 3+1N coordination to this complex and propose to call it “auto-ternary”, with the actual Cu(GHK)(H 2 GHK) stoichiometry.…”

Triggering Cu-coordination change in Cu(ii)-Ala-His-His by external ligands

“…Imidazole is also a relatively strong ternary ligand for XH peptides, as demonstrated recently. 12,19 In these experiments AAH and AH peptides were used as references representing pure 4N and 3N coordination modes, respectively. In the absence of Im, Cu(AHH) shows an absorption band with λmax at 522 nm, in line with the predominant presence (~89%) of the 4N form, (Fig.…”

“…These sites are specific for Cu(II) ions over the other essential metal ions in humans and the respective complexes have been thoroughly described (Scheme 1). 7,[9][10][11][12][13] The XH sequence provides a planar arrangement of three equatorial ligands around the Cu(II) ion with the NH2 of the N-terminus, the Nπ of the imidazole of His and the nitrogen of the peptide bond between X and H (NH2, N, N Im ; called 3N). An external ligand (L) completes this coordination sphere forming 3N+L complexes (in simple model systems L often includes water).…”

N‐Terminal Cu‐Binding Motifs (Xxx‐Zzz‐His, Xxx‐His) and Their Derivatives: Chemistry, Biology and Medicinal Applications

“…Indication that GHK binds Cu in vivo comes from reports stating that GHK is isolated at least partially as a Cu II complex and that Cu II is required for its biological activity . Likewise, α‐factor, which has a WHW N‐terminal sequence, was co‐isolated from cell culture media as Cu II complex, and its Cu II affinity indicates that its Cu II complexed form may be the actual biological species …”

“…[59,60] Likewise, a-factor,w hich has aW HW N-terminal sequence, was co-isolated from cell culture media as Cu II complex, [58] and its Cu II affinity indicates that its Cu II complexed form may be the actual biological species. [17] 5A pplications XZH and XH motifs have been used for av ast variety of applications.H ere, we focus on the relevant biological and medicinal applications, which are the most abundant ones. Other applications,p articularly regarding very intriguing non-biological catalytic properties, have been reported, [61] including similar motifs.…”