Berlin 2005 – scientific programme

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AKB: Biologische Physik

AKB 100: Poster Session I

AKB 100.1: Poster

Saturday, March 5, 2005, 16:45–18:45, Poster TU D

Activation and characterization of a photoswitchabel GFP variant using two-photon absorption — •Marc Schneider¹, Sara Barozzi², Ilaria Testa¹, Mario Faretta², and Alberto Diaspro¹ — ¹INFM Genua, Via Dodecaneso 33, I-16146 Genoa, Italy — ²European Institute of Oncology, Dept of Exp. Oncology, Via Ripamonti 435, I-20141 Milan, Italy

We report about a photoactivatable variant of the Aequorea Victoria green fluorescent protein (PA-GFP). As reported by Patterson and Lippincott−Schwartz¹ this special form of the molecule increases its fluorescence intensity when excited by 488 nm after irradiation with high intensity light with λ=413nm. We will present data on the two-photon induced photoactivation of the PA-GFP molecule as well as two-photon excitation. Therefore experiments were performed using partially purified protein immobilised on microspheres. The molecular switches were irradiated with laser light in a range of wavelength of a Ti:Sapphire laser system coupled to an inverted microscope. The optimum frequency for activation was chosen to investigate fixed cells. A comparison between the conventional activation with a single photon at λ=405nm and two-photons demonstrates the much smaller activation volumes in the cell. .

(1) Patterson, G. H.; Lippincott-Schwarz, J. Science 2002, 297, 1873.