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Art van der Est: Research

Our research focuses on using modern time-resolved electron spin resonance (ESR) spectroscopy to study the structure and function of photosynthetic reaction centres and porphyrin-based model systems. Light excitation of these systems leads to energy and electron transfer reactions involving short-lived paramagnetic intermediates. The spin polarized transient EPR spectra of these species can be used to deduce both structural as well as kinetic information about the functional states.

Our interest in photosynthesis involves understanding how plants and bacteria capture and store sunlight. In particular, we are trying to elucidate the role that protein-cofactor interactions play in controlling  the effeciency and rate of the transmembrane electron transfer in photosynthetic reaction centres.  Transient ESR is especially well-suited for studying the quinone acceptors in these systems and shown that their properties are dramatically different although they are structurally very similar.  Recently, we have begun studying deletion mutants of cyanobacteria which allow both the protein and cofactors to be altered in a controlled way.

The work on porphyrin-based model systems is directed primarily towards understanding the influence of paramagnetic transition metals such as Cu2+ on energy transfer in systems of coupled chromophores.  Our goal is to use the spin polarization generated in these processes to study metallo-proteins which are not otherwise photoactive.