AFM Snapshots of Synthetic Multifunctional Pores with Polyacetylene Blockers: Pseudorotaxanes and Template Effects

Angewandte Chemie International Edition (Impact Factor: 11.34). 08/2005; 44(38):6154 - 6157. DOI: 10.1002/anie.200501886
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    ABSTRACT: A concept to determine enantiomeric excess with synthetic multifunctional pores is introduced. To do so, the poor stereoselectivity of molecular recognition by stimuli-responsive pores is coupled with the stereospecificity of enzymes. With substrates as good and products as poor pore blockers, enzymatic conversion of one enantiomer is shown to readily reveal the concentration of the other one. Calculations suggest that high substrate/product discrimination by the synthetic pores may provide access to the accurate detection of the extreme enantiomeric excess that is of interest in chemistry, pharmacology, and medicine, but otherwise possibly problematic to detect. Validity of the introduced concept is experimentally confirmed with poly-L-glutamate and poly-D-glutamate as enantiomeric substrates with high blockage efficiency, L-glutamate and D-glutamate as enantiomeric products with poor blockage efficiency, subtilisin A as enzyme, and a classical rigid-rod beta-barrel as synthetic pore.
    Chirality 04/2008; 20(3-4):307-12. · 1.72 Impact Factor
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    ABSTRACT: We elaborate on the structural diversity well beyond the biological limitations that becomes accessible with synthetic ion channels and pores, and on the importance of advanced nanoarchitecture to create significant function.
    Molecular BioSystems 11/2007; 3(10):658-66. · 3.35 Impact Factor
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    ABSTRACT: Channel proteins like FhuA can be an alternative to artificial chemically synthesized nanopores. To reach such goals, channel proteins must be flexible enough to be modified in their geometry, i.e. length and diameter. As continuation of a previous study in which we addressed the lengthening of the channel, here we report the increasing of the channel diameter by genetic engineering. The FhuA Δ1-159 diameter increase has been obtained by doubling the amino acid sequence of the first two N-terminal β-strands, resulting in variant FhuA Δ1-159 Exp. The total number of β-strands increased from 22 to 24 and the channel surface area is expected to increase by ~16%. The secondary structure analysis by circular dichroism (CD) spectroscopy shows a high β-sheet content, suggesting the correct folding of FhuA Δ1-159 Exp. To further prove the FhuA Δ1-159 Exp channel functionality, kinetic measurement using the HRP-TMB assay (HRP = Horse Radish Peroxidase, TMB = 3,3',5,5'-tetramethylbenzidine) were conducted. The results indicated a 17% faster diffusion kinetic for FhuA Δ1-159 Exp as compared to FhuA Δ1-159, well correlated to the expected channel surface area increase of ~16%. In this study using a simple "semi rational" approach the FhuA Δ1-159 diameter was enlarged. By combining the actual results with the previous ones on the FhuA Δ1-159 lengthening a new set of synthetic nanochannels with desired lengths and diameters can be produced, broadening the FhuA Δ1-159 applications. As large scale protein production is possible our approach can give a contribution to nanochannel industrial applications.
    Journal of Nanobiotechnology 08/2011; 9:33. · 5.09 Impact Factor