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September 15, 2010 (Vol. 30, No. 16)

Label-Free SPRi Analysis of Peptide Arrays

Advanced Platform Finds Applications in Characterizing Antibodies in Complex Samples

  • Peptides are valuable affinity reagents in proteomics research, useful in generating and characterizing antibodies and in serving as robust probes for protein binding analyses. Array formats are popular because they increase throughput and require only small quantities of reagents.

    Label-free analysis of peptide-protein interactions eliminates the risk of introducing experimental artifacts by chemically modifying protein targets with a label, and  reduces the expense and difficulty of reproducibly labeling multiple targets for multiplex analysis. This article summarizes the use of label-free peptide arrays to characterize antibodies in egg yolk and serum samples.

    The surface plasmon resonance imaging (SPRi) array analysis described in this article requires a gold substrate (chip). A dependable method for making peptide arrays on gold is to synthesize peptides with a terminal cysteine residue, plus a Ser-Gly-Ser-Gly spacer. The thiol group on the cysteine residue is then covalently linked in a specific orientation to the thiol-reactive surface on the chip, while the spacer serves to improve availability of the peptide probe for binding to target proteins.

    For peptides lacking cysteines, an amine-reactive surface such as N-Hydroxysuccinimide has been used for array fabrication. Such surfaces are designed to link probes covalently via available primary amines.

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