Accession Number:



Ultra-Sensitive Microwave Detection of Protein Conformational Changes

Descriptive Note:

Final rept. 1 May 2002-31 Dec 2003

Corporate Author:


Report Date:


Pagination or Media Count:



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 solutions properties in reflection. The slot antennas 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, unfoldingfolding thermodynamics of a protein in solution were measured using a slot antenna affixed to a UVVIS 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.

Subject Categories:

  • Medicine and Medical Research
  • Active and Passive Radar Detection and Equipment
  • Electricity and Magnetism

Distribution Statement: