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

We have studied the reaction of allenylboronic acid pinacol ester with cyclopentadiene with experimental and computational methods. The reaction occurred efficiently with complete Diels–Alder periselectivity and regioselectivity at the proximal double bond. The concerted mechanism for the observed transformation was computed to be favored over competitive addition to the distal double bond, [3,3]-sigmatropic rearrangements, and stepwise radical mechanism. This unprecedented Diels–Alder reaction enables the construction of synthetically versatile boron-substituted cycloadducts.

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.