LETTER RESEARCH
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.
We have established that tetrahedral intermediate 2 is in equilibrium
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Acknowledgements We thank the Patty and Michael Phelps Foundation and
the National Institutes of Health (NIH) National Institute of General Medical
Sciences (GM088237) for funding. Radioisotope production and use were
enabled by a shared instrument grant from the NIH (1S10RR017208). We
thank S. Arlow and C. Kleinlein for preliminary mechanistic work and H. Lee for
assistance with X-ray crystallography. We thank N. A. Stephenson for a synthetic
precursor for S6 as well as the 19F-standard for this substrate.
Author Contributions C.N.N. designed and performed the experiments, with
input from T.R. and J.M.H. C.N.C. analysed the data. T.R. directed the project.
C.N.N. and T.R. prepared the manuscript with input from J.M.H.
Author Information Atomic coordinates and structure factors for the reported
Centre under accession number CCDC-1419728. Reprints and permissions
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