Metabolites were identified according to their m/z value and fragmentation spectra according to reference data
"],"repository":["MetaboLights"],"study_status":["Public"],"ptm_modification":[""],"instrument_platform":["Liquid Chromatography MS - positive - reverse-phase"],"chromatography_protocol":["Separation using reverse phase column was used before sample analysis
"],"publication":["Insights into the stereochemical mechanism of the B12-dependent radical SAM glutamine C- methyltransferases QCMT."],"submitter_affiliation":["Université Paris-Saclay"],"submitter_name":["Olivier BERTEAU"],"organism_part":["blank"],"technology_type":["mass spectrometry assay"],"disease":[""],"extraction_protocol":["No sample extraction was made for these samples
Only dilution before injection
"],"organism":["Methanoculleus thermophilus","reference compound"],"data_transformation_protocol":["No transformation was performed
Qual Browser used to extract the corresponding m/z ratios
"],"study_factor":["Peptide","Name"],"submitter_email":["olivier.berteau@universite-paris-saclay.fr"],"metabolights_link":["https://www.ebi.ac.uk/metabolights/MTBLS14287"],"sample_collection_protocol":["FDVA derivatization conditions for amino acid analyzis
"],"omics_type":["Metabolomics"],"study_design":["ultra-performance liquid chromatography-mass spectrometry","Metabolomics","Methanoculleus thermophilus","peptide","LC MS","blank","reference compound","targeted analysis","Thermo Scientific Vanquish Flex UHPLC System","Thermo Scientific Q Exactive Focus","experimental blank","targeted metabolite profiling"],"curator_keywords":["ultra-performance liquid chromatography-mass spectrometry","Metabolomics","Methanoculleus thermophilus","peptide","LC MS","blank","reference compound","targeted analysis","Thermo Scientific Vanquish Flex UHPLC System","experimental blank","Thermo Scientific Q Exactive Focus","targeted metabolite profiling"],"mass_spectrometry_protocol":["thermo scientific Q exactive focus mass spectrometer
"],"metabolite_name":["l-ala","d-ala"],"additional_accession":[]},"is_claimable":false,"name":"Insights into the stereochemical mechanism of the B12-dependent radical SAM glutamine C- methyltransferases QCMT","description":"Methyl-coenzyme M reductase (MCR) is a crucial enzyme for methanogenesis and harbors several unusual post-translational modifications. Recent studies have identified glutamine C-methyltransferase (QCMT), as a B12-dependent radical SAM enzyme responsible for methylating a glutamine residue within the MCR active site. B12-dependent radical SAM enzymes have the remarkable ability to alkylate unactivated Csp2- and Csp3-atoms in a stereoselective manner. However, the factors influencing the stereo-selectivity and catalytic properties of this emerging superfamily of enzymes remain poorly understood. In this study, we report the mechanistic, structural, and biochemical investigation of several QCMTs. Our findings reveal significant differences among them, notably in their ability to bind cobalamin. In addition, our data support that Cα H-atom abstraction and methyl transfer are not concerted but rather independent processes that require motion within the enzyme's active site. We also demonstrate that QCMT can catalyze, to the best of our knowledge, novel reactions, including the formation of unnatural C-methylated residues, peptide epimerization, reversible H-atom abstraction, and the direct conversion of glycine into D-alanine. Overall, our data are consistent with QCMT being a unique and versatile biocatalyst allowing for the installation of unnatural post-translational modifications and provide a structural and biochemical rationale for the control of the stereochemistry by B12-dependent radical SAM enzymes.","dates":{"publication":"2026-04-28","submission":"2026-04-15"},"accession":"MTBLS14287","cross_references":{"MetaboLights":["MTBLC2456"],"ChEBI":["CHEBI:2456"]}}