Im Fass gefangen: AFM-Untersuchungen identifizieren Wirt-Gast-Komplexe aus β-Fass-Poren und Polymerblockern als Pseudorotaxane. Die nichtstatistische Anordnung der kontrahierten supramolekularen Fässer auf den Polymeren deutet an, dass die Polymertemplate schnell in die β-Fässer einfädeln (siehe Schema) und sich dann langsam hindurchbewegen.
"However the synthesis of these molecules is not trivial and large scale production is difficult . Furthermore the peptide sequence variety is until now very limited and each artificial β-barrel contains only one kind of peptide sequence [21,22]. "
[Show abstract][Hide abstract] 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(1):33. DOI:10.1186/1477-3155-9-33 · 4.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report the design, synthesis, and evaluation of synthetic multifunctional pores with adhesive, that is, electron-deficient naphthalenediimide (NDI) pi-clamps at their inner surface. We find that, in lipid bilayer membranes, comparable synthetic pores with and without pi-clamps have similar, nanomolar activity. Functional relevance of adhesive pi-clamping within synthetic pores is demonstrated by means of an innovative in situ blocker screening method. The obtained line of experimental evidence includes (a) different blockage efficiency with and without pi-clamps (quantified as clamping factors), (b) increasing clamping factors with increasing blocker charge (supportive ion pairing), and, most importantly, (c) increasing clamping factors with increasing aromatic electron donor-acceptor interactions. The availability of advanced synthetic multifunctional pores with refined active sites is important for practical applications in domains such as drug discovery (enzyme inhibitor screening) and diagnostics (multianalyte sensing).
Journal of the American Chemical Society 01/2007; 128(50):16000-1. DOI:10.1021/ja066886+ · 12.11 Impact Factor
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