Ultra-Sensitive Microwave Detection of Protein Conformational Changes
Abstract
We are using pulsed and continuous-wave dielectric spectroscopy for sensing DNA and proteins with high frequency techniques. This is rarely used for proteins and other macromolecules due to their low permittivity. Water, however, is a strong dielectric and the shells of bound water surrounding a macromolecule in solution may be used as a reporter for changes in its conformation or activity. Such measurements have been pursued with resonant cavities or planar waveguides, but optical correlation has been lacking. An alternative is to employ a planar resonant slot antenna, using a network analyzer to measure the solution's properties in reflection. The slot antenna's window permits passage of a light beam, enabling simultaneous dielectric and optical spectroscopic measurements. Here we report two systems, both resonant in the 4-20 GHz regime. In the first, unfolding/folding thermodynamics of a protein in solution were measured using a slot antenna affixed to a UV/VIS cuvette. In the second system, a slot antenna was incorporated into the cell holder of a fluorescence polarization instrument and used to measure binding of synthetic hormones to various receptors. Results from dielectric measurements are in good agreement with results from optical spectroscopies.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 02, 2004
- Accession Number
- ADA422852
Entities
People
- Daniel W. Van Der Weide
- Kimberly M. Taylor
Organizations
- University of Wisconsin–Madison