Structure

The single-molecule (SM) methods permit the observation and manipulation of individual molecules and their properties that are obscured by ensemble-averaging during the conventional bulk measurements. This allows the detection of molecular heterogeneity, rare and short-lived molecular states. Also, it is possible to directly observe dynamic changes in molecular structure. In combination, these advantages bestow the possibility to study molecular interactions.

 

In the SM group we use fluorescence methods to study the dynamics of DNA interactions with restriction enzymes requiring two DNA targets for their function; the role of pigment composition in non-photochemical quenching in the pigment–protein complexes of higher plants; the mechanisms of interactions of procariotic Argonaute proteins with nucleic acids. In addition to the study of biological molecules, we contribute to the expansion of the SM toolkit: we have improved the sensitivity of the tethered fluorophore motion (TFM), by exploiting the dependence of the fluorophore intensity on its position in the gradient of the evanescent excitation; have implemented simpler “DNA curtains”–—high throughput method to study DNA–protein interactions.

 

In the laboratory of non-linear optical microscopy we employ the method of coherent anti-Stokes Raman spectroscopy (CARS) to perform chemically specific imaging of various biological structures. Intrinsic molecular vibrations are used for the imaging contrast thus making the extraneous labelling unnecessary and therefore enabling the observation without altering the chemical and/or structural properties. Since CARS signal is generated coherently, it is a few orders of magnitude more intense than the spontaneous Raman scattering, which allows high-speed image acquisition.

 

In the laboratory we are also developing the wide-field second harmonic generation (SHG) microscopy for the fast imaging of collagen structures in the biological tissues intended as a possible alternative to the conventional histological analysis suitable for the express diagnostics.