On-surface assembly of coiled-coil heterodimers

White, S. J., Morton, D. W. A., Cheah, B. C. , Bronowska, A., Davies, A. G., Stockley, P. G., Wälti, C. and Johnson, S. (2012) On-surface assembly of coiled-coil heterodimers. Langmuir, 28(39), pp. 13877-13882. (doi: 10.1021/la3025149) (PMID:22934624) (PMCID:PMC4820041)

Abstract

The coiled coil is a widespread protein motif responsible for directing the assembly of a wide range of protein complexes. To date, research has focused largely on the solution phase assembly of coiled-coil complexes. Here, we describe an investigation into coiled-coil heterodimer assembly where one of the peptides is immobilized directly onto a gold electrode. Immobilization is achieved by the introduction of a unique cysteine residue at the C terminus, allowing for covalent and orientated attachment to a thiol-reactive surface, here the gold electrode. We show an electrochemical impedance of the resulting self-assembled polypeptide monolayer around |Z| = 4 × 104 Ω cm2 at 100 mHz with a minimum phase angle of −84°, consistent with the formation of a densely packed, insulating layer. The thickness of the peptide monolayer, as measured using ellipsometry, is around 3 nm, close to that expected for a self-assembled monolayer assembled from helical peptides. Crucially, we find that the efficiency of dimerization between a peptide in solution and its coiled-coil partner peptide immobilized on a surface is strongly dependent upon the density of the immobilized peptide layer, with dimer assembly being strongly suppressed by high-density peptide monolayers. We thus develop an approach for controlling the density of the immobilized peptide by diluting the monolayer with a thiolated, random-coil peptide to modulate dimerization efficiency and demonstrate electrochemical detection of highly specific, coiled-coil heterodimer on-surface assembly.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Cheah, Dr Boon Chong
• Authors: White, S. J., Morton, D. W. A., Cheah, B. C., Bronowska, A., Davies, A. G., Stockley, P. G., Wälti, C., and Johnson, S.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: Langmuir
• Publisher: American Chemical Society
• ISSN: 0743-7463
• ISSN (Online): 1520-5827