Absorption and spontaneous emission of photons by fluorescent molecules are often used to probe interactions between biological macromolecules. In this talk I will overview our development of technologies for determining the supramolecular organization of proteins based on known as well as less known classical and quantum physics effects.

One of our methods, dubbed Förster Resonance Energy Transfer (FRET) Spectrometry, probes relative distances between and orientation of fluorescent molecules within a complex via quantum energy transfer between their transition dipoles. A second method, Fluorescence Intensity Fluctuation (FIF) Spectrometry, probes spatial fluctuations in fluorescence intensities to determine the number of molecules comprising a molecular complex. Finally, a quantum effect is described which relates the spectra of single-molecule fluorescence to the orientation of the molecular transition dipoles and could lead to methods for determining the orientation of proteins within complexes in their natural milieu. This is based on our recent attempts to refine the method of quantization of EM fields to include fields from single emitters, which also will be succinctly described.

In addition to addressing many interesting physics questions, our studies also provide life scientists with tools for understanding the biological role of supramolecular association.