title: Nanopore investigation of the stereoselective interactions between Cu(2+) and D,L-histidine amino acids engineered into an amyloidic fragment analogue.
abstract: Stereochemistry is an essential theme for a number of industries and applications, constructed around discriminating various chiral enantiomers, including amino acids, chiral metal complexes, and drugs. In this work, we designed a set of peptide mutants of the human amyloidic Aβ1-16 sequence, known to display an effective Cu(2+) coordinating pocket provided mainly by the intramolecular His-6, His-13, and His-14 residues, that were engineered to contain L- and D-His enantiomers in positions 6 and 13 and provide a local coordination environment with distinct Cu(2+) binding geometries and affinities. We examined the mechanism of selective chiral recognition of Cu(2+) by such mutant peptides, by quantifying their stochastic sensing in real time with a single α-hemolysin (α-HL) protein immobilized in a planar lipid membrane, while incubated in various concentrations of Cu(2+). Our data reveal that the Cu(2+)-binding affinity lies within the micromolar range, and decreases by orders of magnitude as L-His is replaced with its Denantiomer, with the effect being prevalent when such changes were inflicted on the His-6 residue. The presented results demonstrate the feasibility of tuning the metal selectivity in a relatively simple peptide substrate by enantiomeric replacement of key metal binding residues and illustrates the potential of the protein nanopores as a promising approach to quantify the chiral recognition of l/d amino acids by metals.
authors.affiliation: Department of Interdisciplinary Research, Alexandru Ioan Cuza University , Blvd. Carol I, No. 11, Iasi 700506, Romania.
authors.forename: Irina
authors.initials: I
authors.lastname: Schiopu
authors.forename: Sorana
authors.initials: S
authors.lastname: Iftemi
authors.forename: Tudor
authors.initials: T
authors.lastname: Luchian
mesh_terms: D000596:Amino Acids / Q000737:chemistry* / Q000378:metabolism; D000682:Amyloid / Q000737:chemistry*; D016229:Amyloid beta-Peptides / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry*; D006801:Humans; D008954:Models, Biological; D058608:Nanopores; D015202:Protein Engineering; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D000682:Amyloid; D016229:Amyloid beta-Peptides; D006639:Histidine; D003300:Copper