Competitive electron transfers from a tyrosyl side-chain and peptide bond in the photodegradation of Ntosyl -aminomethylamides: an insight into photosynthesis and photodamage in the biological oxidation of water?

Photo-excited N-tosyl derivatives of phenylalanyl- and, more particularly, Omethyltyrosylmethylamides undergo electron transfer from aryl to tosyl groups whereas the photo-degradation of aliphatic analogues is initiated by electron transfer from the peptide bond, suggesting the latter as one possible reason for the rapid turnover of the D1 protein in biological water oxidation when the essential mediating role of tyrosine 116 in the PSII complex is inhibited.