Fluorescence blinking of single major light-harvesting complexes

Recent time-resolved studies have revealed the switching behavior of single photosynthetic light-harvesting complexes. In this work, we suggest a conceptual diffusion-controlled model, which is able to describe essential protein dynamics underlying this switching phenomenon. The calculated blinking statistics is compared with the experimental results measured under various experimental conditions and not only reproduces the power-law behavior at intermediate times, but also follows the experimentally observed deviations from such behavior on a shorter timescale. We find that even under ordinary light-harvesting conditions, some antenna complexes are quenched and their fraction noticeably increases in a more acid environment. As a result, the lability of the protein scaffold allows the coexistence of light-harvesting and excitation-quenching states and therefore gives rise to regulatory switching known as non-photochemical quenching.