Research

Optical single molecule methods

Our longest endeavors have been in the development of optical techniques to aid fundamental biological research, which is in need of quantitative methods to determine their key processes.

With all the data known about protein interactions and interaction networks from biochemical analysis, there still remains the important task of in situ proteomics, i.e. determining the thermodynamic and kinetic parameters of certain reactions in the cellular environment. Further, to understand how cells polarize and develop into organisms, we need quantitative methods to determine concentration gradients and reaction/diffusion coefficients of key factors.

In addition to new imaging technology that aims at higher resolution, strategies to determine dynamics of processes are of great importance. Our group has pioneered and applied several ultrasensitive spectroscopic techniques to analyze dynamics and interactions of biomolecules in living cells. Fluorescence Correlation Spectroscopy (FCS) is a powerful means for the study of concentrations, translocation processes, molecular association or enzymatic turnovers on time scales from microseconds to seconds. Its variant dual-color cross-correlation (FCCS), is particularly useful to quantify molecular interactions between distinct species and thus, a very promising tool to quantify molecular complex formation on a single molecule scale.

During the past years, we applied FCS to a variety of cell-associated phenomena, among them protein-protein binding, enzymatic reactions, endocytosis, and gene delivery, as well as morphogen gradient formation in living Zebrafish embryos.