FluorinatedS‐Adenosylmethionine as a Reagent for Enzyme‐Catalyzed Fluoromethylation

Abstract

Strategic replacement of protons with fluorine atoms or functional groups with fluorine-containing fragments has proven a powerful strategy to optimize the activity of therapeutic compounds. For this reason, the synthetic chemistry of organofluorides has been the subject of intense development and innovation for many years. By comparison, the literature on fluorine biocatalysis still makes for a slim chapter. Herein we introduce S-adenosylmethionine (SAM) dependent methyltransferases as a new tool for the production of fluorinated compounds. We demonstrate the ability of halide methyltransferases to form fluorinated SAM (S-adenosyl-S-(fluoromethyl)-L-homocysteine) from S-adenosylhomocysteine and fluoromethyliodide. Fluorinated SAM (F-SAM) is too unstable for isolation, but is accepted as a substrate by C-, N-and O-specific methyltransferases for enzyme-catalyzed fluoromethylation of small molecules.

Biocatalysis as Key to Sustainable Industrial Chemistry

“…Several orthogonal and mutually beneficial developments have come from bottom-up approaches. [72] Versatile biocatalytic reaction platforms provide the experimentally rooted background for extending the scope of classical and new reaction classes, such as selective biocatalytic hydrolyses, [73] oxidations, [74] reductions, [75] glycosylations, [76] phosphorylations, [77] methylations and fluoromethylations, [78,79] addition [80] and elimination reactions, [81] and carboxylations. [82,83] The development of new-to-nature biocatalytic reactions [84] enables biocatalysis to enter completely new fields, such as sustainable silicon chemistry.…”

Discovery and Characterization of the Metallopterin-Dependent Ergothioneine Synthase from Caldithrix abyssi

“… 45 , 46 Ca MES-containing cells ( E. coli Δmtn) grown in the presence of N α-methyl fluoro-TMH ( 4 : F-TMH, Figure 2 ) instead of TMH produced N α-methyl fluoro ergothioneine ( 3 : F-ERG, m / z calcd: 248.0864; obsd: 248.086) with yields that correlate with the concentration of F-TMH in the medium ( Figure S8 ). Since F-TMH is an exclusively synthetic compound, 47 we can eliminate any possibility that the detected F-ERG originates from the growth medium instead from de novo biosynthesis by Ca MES. Finally, since Ca ME is translated from a synthetic codon-optimized gene, we can also exclude the possibility that the foreign nucleic acid instead of the translated protein is responsible for the sulfurization of TMH in E. coli .…”

“…Isotopologues of ergothioneine and F-TMH were produced and characterized as described in previous work. 20 , 47 …”

“…Expression plasmids were purchased from Biocat GmbH. Isotopologues of ergothioneine and F-TMH were produced and characterized as described in previous work. , …”

Biomimetic S‐Adenosylmethionine Regeneration Starting from Multiple Byproducts Enables Biocatalytic Alkylation with Radical SAM Enzymes**

“…Another approach for SAM regeneration uses the reverse reaction of a halide MT (E.C. 2.1.1.165) to directly re‐methylate SAH using methyl iodide with up to 500 TTN; [64] this has been expanded to the use of other alkyl halides for general alkylation [65–68] . Both regeneration systems have in common that they rely on SAH formed in the MT reaction.…”