期刊
LANGMUIR
卷 31, 期 1, 页码 387-396出版社
AMER CHEMICAL SOC
DOI: 10.1021/la504243r
关键词
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资金
- UAIC [GI - 2014 - 08]
- [PN-II-ID-PCCE-2011-2-0027]
- [PN-II-PT-PCCA-2011-3.1-0595]
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 A beta(1-16) sequence, known to display an effective Cu2+ 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 Cu2+ binding geometries and affinities. We examined the mechanism of selective chiral recognition of Cu2+ by such mutant peptides, by quantifying their stochastic sensing in real time with a single a-hemolysin (alpha-HL) protein immobilized in a planar lipid membrane, while incubated in various concentrations of Cu2+. Our data reveal that the Cu2+-binding affinity lies within the micromolar range, and decreases by orders of magnitude as l-His is replaced with its d-enantiomer, 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.
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