tyrosine-based charge transfer

In photosystem II, YD forms a light-induced stable radical whereas YZ functions as an essential charge relay that oxidizes the catalytic Mn4CaO5 cluster during the four photo-oxidation reactions.

In Escherichia coli class 1a ribonucleotide reductase, Y122O• in the β2 subunit is a stable radical in isolated β2 but is activated for rapid PCET in the α2β2 substrate/effector complex.

At physiological pH, tyrosine oxidation is associated with deprotonation of the phenolic oxygen, producing a proton-coupled electron transfer reaction.

In bioenergetic reactions, long-distance electron transfer can proceed via a hopping mechanism in which tyrosine serves as a transiently oxidized and reduced intermediate.

The review compares natural tyrosine-based charge transfer systems with bioengineered proteins and biomimetic compounds used to investigate related mechanisms.

Tyrosine-based PCET is important in photosystem II and ribonucleotide reductase.