Thermal effect on Aequorea green fluorescent protein anionic and neutral chromophore forms fluorescence
1IN-CQFM, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal. andreasantos@fm.ul.pt
Abstract:
The emission behaviour of Aequorea green fluorescent protein (A-GFP) chromophore, in both neutral (N) and anionic (A) form, was studied in the temperature range from 20 °C to 75 °C and at pH = 7. Excitation wavelengths of 399 nm and 476 nm were applied to probe the N and A forms environment, respectively. Both forms exhibit distinct fluorescence patterns at high temperature values. The emission quenching rate, following a temperature increase, is higher for the chromophore N form as a result of the hydrogen bond network weakening. The chromophore anionic form emission maximum is red shifted, upon temperature increase, due to a charge transfer process occurring after A form excitation.
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