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Biomolecular model systems

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We frequently use biomolecular model interaction systems in order to demonstrate biosensor concepts related to immobilization, arraying, detection and quantification. Such systems are also important in the context of building supramolecular structures. Although commercially available biomolecules (often an antibody and its antigen) are sometimes suitable in this respect, the greater flexibility and robustness of designed, synthethic polypeptides with affinity to specific proteins have proven invaluable in many applications.

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Helix-loop-helix polypeptide scaffolds

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In recent years, 42-amino acid, helix-loop-helix polypeptides that dimerize to form four-helix bundles have become important components in many of our projects. Depending on the amino acid sequence and external factors such as pH and the presence of metal ions, these peptides are prone to homo- or heterodimerization. This controllable folding property, together with the ease by which molecules such as fluorophores, affinity ligands and immobilization handles can be covalently incorporated, makes the helix-loop-helix peptides attractive both as scaffolds for protein sensing and for the development of nanoscale materials. In this context, they have been used for nanoparticle assembly and for the formation of fibrous structures (figure).

Related publications:

Aili D, Selegård R, Baltzer L, Enander K, and Liedberg B: "Colorimetric protein sensing by controlled assembly of gold nanoparticles functionalized with synthetic receptors." Small 5:2445-2452 (2009) Abstract

Aili D, Enander K, Baltzer L, and Liedberg B: "Assembly of polypeptide-functionalized gold nanoparticles through a heteroassociation- and folding-dependent bridging" Nano Letters 8:2473-2478 (2008) Abstract

Aili D, Tai F-I, Enander K, Baltzer L, and Liedberg B: "Self-assembling fibers and nano-rings from disulphide-linked helix-loop-helix polypeptides." Angewandte Chemie, Int. Ed. 47 :5554-5556 (2008)

Aili D, Enander K, Rydberg J, Nesterenko I, Björefors F, Baltzer L, and Liedberg B: "Folding induced assembly of polypeptide decorated gold nanoparticles." Journal of the American Chemical Society 130 :5780-5788 (2008) Abstract

Aili D, Enander K, Rydberg J, Lundström I, Baltzer L, and Liedberg B: "Aggregation-induced folding of a de novo designed polypeptide immobilized on gold nanoparticles." Journal of the American Chemical Society 128 :2194-2195 (2006) Abstract

Enander K, Aili D, Baltzer L, Lundström I, and Liedberg B: "Alpha-helix-inducing dimerization of synthetic polypeptide scaffolds on gold." Langmuir 21:2480-2487 (2005) Abstract

Enander K, Dolphin G T, Liedberg B, Lundström I, and Baltzer L: "A versatile polypeptide platform for integrated recognition and reporting – affinity arrays for protein-ligand interaction analysis" Chemistry – A European Journal 10:2375-2385 (2004) Abstract

Enander K, Andersson L K, Dolphin G T, Liedberg B, Lundström I, and Baltzer L: "Designed, folded polypeptide scaffolds that combine key biosensing events of recognition and reporting" Journal of Organic Chemistry 67:3120-3123 (2002)

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A minimized peptide sequence based on a virus protein

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A second model interaction system available in our group is a synthetic, 18-amino acid peptide (pTMVP; corresponding to the blue and red sequence in the picture) derived from the tobbacco mosaic virus coat protein (green) and a recombinant IgG-Fab fragment. pTMVP was recently used to engineer molecular biosensor elements towards the Fab fragment by incorporation of a ratiometric, environmentally sensitive fluorophore. Further, three peptide variants were arrayed to demonstrate how the use of several ligands with different affinities towards a common analyte can extend the dynamic range of analyte quantification, compared to when only one ligand is being used.

Related publications:

Andersson O, Nikkinen H, Kanmert D, and Enander K: "A multiple-ligand approach to extending the dynamic range of analyte quantification in protein microarrays." Biosensors and Bioelectronics 24:2458-2464 (2009) Abstract

Aili D, Selegård R, Baltzer L, Enander K, and Liedberg B: "Colorimetric protein sensing by controlled assembly of gold nanoparticles functionalized with synthetic receptors." Small 5:2445-2452 (2009) Abstract

Enander K, Choulier L, Olsson L, Yushchenko D, Kanmert D, Klymchenko A, Demchenko A, Mély Y, and Altschuh D: "A peptide-based, ratiometric biosensor construct for direct fluorescence detection of a protein analyte." Bioconjugate Chemistry 19:1864-1870 (2008) Abstract

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Contact: Karin Enander (karen@ifm.liu.se)

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Responsible for this page: Erik Martinsson
Last updated:06/01/10