Catalytic Alkylation Using a Cyclic S‐Adenosylmethionine Regeneration System

Abstract

S-Adenosylmethionine-dependent methyltransferases are versatile tools for the specific alkylation of many compounds, such as pharmaceuticals, but their biocatalytic application is severely limited owing to the lack of a cofactor regeneration system. We report a biomimetic, polyphosphate-based, cyclic cascade for methyltransferases. In addition to the substrate to be methylated, only methionine and polyphosphate have to be added in stoichiometric amounts. The system acts catalytically with respect to the cofactor precursor adenosine in methylation and ethylation reactions of selected substrates, as shown by HPLC analysis. Furthermore, H and C NMR measurements were performed to unequivocally identify methionine as the methyl donor and to gain insight into the selectivity of the reactions. This system constitutes a vital stage in the development of economical and environmentally friendly applications of methyltransferases.

S‐Adenosyl Methionine Cofactor Modifications Enhance the Biocatalytic Repertoire of Small Molecule C‐Alkylation

“…We envisage that blending directed evolution strategies with cofactor analogue mapping, and new strategies to recycle the SAH product formed by Calkylation [15,44] will provide new opportunities to identify enzyme variants with wider substrate promiscuity. Key to the success of this approach is the compatibility of SalL and NovO to couple in situ generation of SAM/SAE cofactor analogues (SalL) with C-(m)ethyl transfer (NovO).…”

“…[11][12][13] However,o btaining regiospecificity,p articularly when this is required at alate-stage in asynthetic workflow,is an enduring challenge. [14][15][16][17] Ther epertoire of C-methylation extends to small molecules,which opens up opportunities to tailor these enzymes as ag eneral platform for biocatalytic C À Cb ond formation (Figure 1a). [14][15][16][17] Ther epertoire of C-methylation extends to small molecules,which opens up opportunities to tailor these enzymes as ag eneral platform for biocatalytic C À Cb ond formation (Figure 1a).…”

“…[20,21] One limitation of this process is the need to prepare these cofactors by chemical synthesis,w hich is laborious,l ow yielding,a nd produces both epimers at the sulfur center. [15,29,30] One example of this one-pot process is the generation of cofactor analogues in situ from either ClDAo rA TP and (m)ethionine, [15,[29][30][31][32][33] followed by C-(m)ethyl transfer catalyzed by aM Tase (Figure 1b). [27,28] Am ore step-and atom-efficient strategy is to couple cofactor formation with C-alkyl transfer.…”

“…[27,28] Am ore step-and atom-efficient strategy is to couple cofactor formation with C-alkyl transfer. [15,27,29,35,36] Although in-depth knowledge of the substrate promiscuity of C-MTases has been garnered from structural and mutagenesis studies, [17,19,20,37] little is known about how the structural features of the SAM cofactor itself influences the yield and scope of C-alkylation. [34] ClDAi sashelf-stable,a tom-economical adenosine source for such aprocess catalyzed by SalL compared to ATP, which is asubstrate for SAM production by methionine adenosyltransferase (MAT).…”

An ortho C-methylation/O-glycosylation motif on a hydroxy-coumarin scaffold, selectively installed by biocatalysis

“…12,13 On transferring the methyl group from SAM to the acceptor substrate, MTs release S-adenosyl-L-homocysteine (SAH) as their second product. 14,15 GTs catalyze glycosylation of the acceptor substrate while releasing the nucleotide moiety from the sugar donor. 13,16 MTs and GTs exhibiting a relatively flexible substrate specificity were exploited in previous studies to further the diversity in natural product structures.…”