Conformational control of cofactors in nature : the influence of protein induced macrocycle distortion on the biological function of tetrapyrroles in photosynthesis

Abstract

This thesis details new research into the influence of nonplanar distortions upon the function of porphyrin based cofactors in proteins via analysis of structural data deposited in the Protein Data Bank (PDB) combined with quantum molecular modelling. Previous reports of conserved macrocycle conformations across related proteins (e.g., twisted haems in peroxidases) together with physicochemical studies on nonplanar porphyrins led to the idea that protein induced nonplanarity could be a modulatory parameter exploited to affect efficient biological function. Whilst the phenomena has been investigated substantially in haemoproteins, photosynthetic systems have received less attention and so this work treats reaction centres (RC) and the tetrahaem cytochrome subunit (RC-cyt) from purple bacteria, and the light-harvesting Fenna-Matthews-Olson (FMO) protein from green bacteria.