Deconvolving Single-Molecule Intensity Distributions for Quantitative Microscopy Measurements

Abstract

In fluorescence microscopy, images often contain puncta in which the fluorescent molecules are spatially clustered. This article describes a method that uses single-molecule intensity distributions to deconvolve the number of fluorophores present in fluorescent puncta as a way to "count" protein number. This method requires a determination of the correct statistical relationship between the single-molecule and single-puncta intensity distributions. Once the correct relationship has been determined, basis histograms can be generated from the single-molecule intensity distribution to fit the puncta distribution. Simulated data were used to demonstrate procedures to determine this relationship, and to test the methodology. This method has the advantages of single-molecule measurements, providing both the mean and variation in molecules per puncta. This methodology has been tested with the avidin-biocytin binding system for which the best-fit distribution of biocytins in the sample puncta was in good agreement with a bulk determination of the avidin-biocytin binding ratio.

Robust assessment of protein complex formation in vivo via single-molecule intensity distributions of autofluorescent proteins

“…As suggested in Ref. 24, there might be other experimental factors that can lead to asymmetric intensity distributions.…”

Membrane heterogeneity – from lipid domains to curvature effects

“…Note that single-molecule intensity distributions have an intrinsic asymmetry due to the influence of the detection probability. As suggested in (223) there might be other experimental factors that can lead to asymmetric intensity distributions.…”

Synchronous optical and electrical detection of biomolecules traversing through solid-state nanopores

“…5͑a͔͒ displayed a markedly different photon distribution and is well-approximated by a single Gaussian, as expected for a random noise source. Previous studies 30 showed that the intensity of a population of fluorescently tagged molecules, where each molecule is labeled with "n" fluorophores, is a smooth long-tailed distribution. It is therefore interesting to note that our data reflect a multipeak intensity distribution.…”