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Publication Abstract from PubMed

The radical S-adenosyl-l-methionine tryptophan lyase uses radical-based chemistry to convert l-tryptophan into 3-methyl-2-indolic acid, a fragment in the biosynthesis of the thiopeptide antibiotic nosiheptide. This complex reaction involves several successive steps corresponding to (i) the activation by a specific hydrogen-atom abstraction, (ii) an unprecedented *CO2(-) radical migration, (iii) a cyanide fragment release, and (iv) the termination of the radical-based reaction. In vitro study of this reaction is made more difficult because the enzyme produces a significant amount of a shunt product instead of the natural product. Here, using a combination of X-ray crystallography, electron paramagnetic resonance spectroscopy, and quantum and hybrid quantum mechanical/molecular mechanical calculations, we have deciphered the fine mechanism of the key *CO2(-) radical migration, highlighting how the preorganized active site of the protein tightly controls this reaction.

Radical S-Adenosyl-l-methionine Tryptophan Lyase (NosL): How the Protein Controls the Carboxyl Radical *CO2(-) Migration.,Amara P, Mouesca JM, Bella M, Martin L, Saragaglia C, Gambarelli S, Nicolet Y J Am Chem Soc. 2018 Nov 16. doi: 10.1021/jacs.8b09142. PMID:30418774^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.