Osnabrück 2002 – wissenschaftliches Programm

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SYBP: Biophotonik

SYBP 1: Einzelmolekülmethoden I

SYBP 1.4: Hauptvortrag

Donnerstag, 7. März 2002, 12:30–13:00, HS 11/215

One- and two-photon microscopy of single molecules and proteins — •Thomas Basche — Institut für Physikalische Chemie, Universität Mainz

The vast majority of the numerous applications of single molecule microscopy and spectroscopy rely on the detection of the fluorescence emission after one-photon excitation. In combination with a confocal set-up a very versatile experimental tool is readily available for studies under ambient conditions. As a more recent example the study of photochemical reactions at the single molecule level will be presented.

Under certain circumstances it might be advantageous to employ a two-photon excitation scheme. A typical example is the imaging of aromatic amino acids which are abundant in many biopolymers but which have to be excited in the UV. In this context we have examined the feasibility to observe single protein molecules via their intrinsic tryptophan emission after two-photon excitation. In particular we have studied a 24-meric hemocyanin containing 148 tryptophans. Although low emission yield and photobleaching appear to be serious problems, we have achieved to follow the diffusion of individual proteins by fluorescence correlation spectroscopy after two-photon excitation.