JoAnne Stubbe – Kauzmann Lecture

Radicals: your Life is in their hands

It will come as a surprise to many chemists, that Nature uses free radical chemistry in essential metabolic pathways. She has figured out how to harness the reactivity of these species to carry out very difficult chemical transformations with exquisite specificity. I will discuss the role of “good” radicals in biology using ribonucleotide reductases (RNRs) as a paradigm, a problem that my lab has investigated for 30 years.   Specifically unnatural tyrosine analogs site-specifically incorporated into each subunit of the enzyme to study an oxidation over a distance of 35 angstroms between a tyrosyl radical and cysteine in RNR’s subunits will be discussed. Evidence in support of the current model for this reaction using time-resolved biophysical methods (PELDOR, HF-EPR, HF- ENDOR, Mössbauer spectroscopies) and photo-RNRs will be presented.