The determination of the absolute configuration of chiral alcohols and amines is typically carried out with modified Mosher methods involving a double-derivatization strategy. On the other hand, the number of robust and reliable methods to accomplish that goal using a single derivatization approach is much less abundant and mainly limited to secondary alcohols or primary amines. Herein, we report a conceptually novel strategy to settle the most likely absolute configuration of a wide variety of substrates and chiral derivatizing agents following a single-derivatization experiment coupled with quantum calculations of NMR shifts and DP4+ analysis. Using an ambitious set of 114 examples, our methodology succeeded in setting the correct absolute configuration of the substrates in 96% of the cases. The classification achieved with secondary alcohols, secondary amines, and primary amines herein studied was excellent (100%), whereas more modest results (89%) were observed for primary and tertiary alcohols. Moreover, a new DP4+ integrated probability was built to strengthen the analysis when the NMR data of the two possible diastereoisomers are available. The suitability of these methods in solving the absolute configuration of two relevant cases of stereochemical misassignment ((+)- erythro-mefloquine and angiopterlactone B) is also provided.
Oxidation of protein methionines to methionine-sulfoxides (MetOx) is associated with several age-related diseases.I nh ealthy cells, MetOxi sr educed to methionineb yt wo families of conserved methionine sulfoxide reductase enzymes, MSRA and MSRB that specifically target the So rR-diastereoisomerso fm ethionine-sulfoxides, respectively.T od irectly interrogate MSRA and MSRB functions in cellular settings, we developed an NMR-based biosensor that we call CarMetOx to simultaneously measure both enzyme activities in single reaction setups.W e demonstrate the suitability of our strategy to delineate MSR functions in complex biological environments, including cell lysates and live zebrafish embryos. Thereby,weestablish differences in substrate specificities between prokaryotic and eukaryotic MSRs and introduce CarMetOxa s ah ighly sensitive tool for studying therapeutic targets of oxidative stress-related human diseasesa nd redox regulated signaling pathways. Oxidationo fm ethionine side chains is ah allmark of cellular ageing and oxidative stress. [1] Methionine oxidationp roduces methionine-sulfoxides (MetOx), with ac hiral centera tt he sulfur atom giving rise to two diastereoisomers, designated Rand S-MetOx (Figure S1 ai nt he Supporting Information). [2] Under physiological conditions, methionine sulfoxides are re
Oxidation of protein methionines to methionine-sulfoxides (MetOx) is associated with several age-related diseases. In healthy cells, MetOx is reduced to methionine by two families of conserved methionine sulfoxide reductase enzymes, MSRA and MSRB that specifically target the S-or R-diastereoisomers of methioninesulfoxides, respectively. To directly interrogate MSRA and MSRB functions in cellular settings, we developed an NMR-based biosensor that we call CarMetOx to simultaneously measure both enzyme activities in single reaction setups. We demonstrate the suitability of our strategy to delineate MSR functions in complex biological environments that range from native cell lysates to zebrafish embryos. Thereby, we establish differences in substrate specificities between prokaryotic and eukaryotic MSRs and introduce CarMetOx as a highly sensitive tool for studying therapeutic targets of oxidative stress-related human diseases and redox regulated signaling pathways. Our approach further extends high-resolution incell NMR measurements of exogenously delivered biomolecules to an entire multicellular organism.
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