Paper Citing NAMD - Abstract
Pinto da Silva, Luis; Esteves da Silva, Joaquim C. G.
A Theoretical Analysis of the Potential Role of pi-pi Stacking Interactions in the Photoprotolytic Cycle of Firefly Luciferin
CHEMPHYSCHEM, 15:3761-3767, DEC 1 2014
Firefly oxyluciferin is a photoacid that presents a pH-sensitive fluorescence, which results from pH-dependent changes on the conformation of self-aggregated - stacking complexes. Luciferin is a derivative of oxyluciferin with very similar fluorescence and photoacidic properties. This similarity indicates that luciferin is also expected to be able to form - stacking complexes, but no pH-sensitive fluorescence is found for this compound. Here, a theoretical approach is used to rationalize this finding. We have found that luciferin only forms - stacking complexes in the ground state at acidic pH. At basic pH and in the excited state, luciferin is present as a dianion. This species is not able to self-aggregate, owing to repulsive electrostatic interactions. Thus, this emissive species is not subject to - stacking interactions; this explains its pH-insensitive fluorescence.
