Fluorescence Correlation Spectroscopy of Flavins and Flavoproteins

Abstract

The remarkable revival of fluorescence correlation spectroscopy (FCS), stimulated by major technical improvements, has led to novel insights into dynamical processes occurring in biological macromolecules over a large time span [2.1–2.3]. The application of FCS has enabled the retrieval of information on the properties of single biomolecules as distinguished from the collective properties of a whole molecular ensemble [2.4,2.5]. The FCS technique is not confined to clear solutions of single purified biomolecules, since the next challenging step to apply the technique to living cells has already been taken [2.6,2.7]. To date, most FCS experiments have been restricted to fluorescent dye molecules, which possess the ability to emit a large number of fluorescence photons before being destroyed. The application of FCS to natural fluorophores has been extremely limited, since the fluorescent moiety usually does not have favorable properties for FCS. The famous green fluorescent protein (GFP) [2.8] was the first example where FCS provided very specific dynamic information on a natural fluorophore [2.9,2.10]. However, in the latter two references the fluorophore in GFP was engineered to yield more brightness and a higher absorption cross section in the blue-green spectral range. The natural occurrence of GFP is limited to a few species of marine organisms.KeywordsFluorescence Correlation SpectroscopyAntenna ProteinFluorescence PhotonAutocorrelation TraceTriplet LifetimeThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.