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Amino Acid Oxidation: A Combined Study of Cysteine Oxo Forms by IRMPD Spectroscopy and Simulations
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Dr. Debora Scuderi Prof. Enrico Bodo Dr. Barbara Chiavarino Prof. Simonetta Fornarini Prof. Maria Elisa Crestoni 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(48):17239-17250
The redox activity of cysteine sulfur allows numerous post‐translational protein modifications involved in the oxidative regulation of metabolism, in metal binding, and in signal transduction. A combined approach based on infrared multiple photon dissociation spectroscopy at the Centre Laser Infrarouge d'Orsay (CLIO) free electron laser facility, calculations of IR frequencies, and finite temperature ab initio molecular dynamics simulations has been employed to characterize the gas‐phase structures of deprotonated cysteine sulfenic, sulfinic, and sulfonic acids, [cysSOx]? (x=1, 2, 3, representing the number of S‐bound oxygen atoms), which are key intermediates in the redox‐switching chemistry of proteins. The ions show different structural motifs owing to preferential binding of the proton to either the carboxylate or sulfur‐containing group. Due to the decreasing basicity of the sulfenic, sulfinic, and sulfonic terminals, the proton bound to SO? in [cysSO]? migrates to the carboxylate in [cysSO3]?, whereas it turns out to be shared in [cysSO2]?. Evidence is gathered that a mixture of close‐lying low‐energy conformers is sampled for each cysteine oxo form in a Paul ion trap at room temperature. 相似文献
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Back Cover: Reinterpretation of Dynamic Vibrational Spectroscopy to Determine the Molecular Structure and Dynamics of Ferrocene (Chem. Eur. J. 50/2016)
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Dr. Stephen P. Best Prof. Feng Wang M. Tauhidul Islam Shawkat Islam Dr. Dominique Appadoo Ryan M. Trevorah Prof. Christopher T. Chantler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(50):18268-18268
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Inside Back Cover: Circularly Polarized Luminescence from Axially Chiral BODIPY DYEmers: An Experimental and Computational Study (Chem. Eur. J. 45/2016)
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Francesco Zinna Dr. Torsten Bruhn Dr. Ciro A. Guido Dr. Johannes Ahrens Prof. Martin Bröring Prof. Lorenzo Di Bari Prof. Gennaro Pescitelli 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(45):16323-16323
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Complexes of PheAla and AlaPhe with alkali metal ions Na+ and K+ are generated by electrospray ionization, isolated in the Fourier‐transform ion cyclotron resonance (FT–ICR) ion trapping mass spectrometer, and investigated by infrared multiple‐photon dissociation (IRMPD) using light from the FELIX free electron laser over the mid‐infrared range from 500 to 1900 cm?1. Insight into structural features of the complexes is gained by comparing the obtained spectra with predicted spectra and relative free energies obtained from DFT calculations for candidate conformers. Combining spectroscopic and energetic results establishes that the metal ion is always chelated by the amide carbonyl oxygen, whilst the C‐terminal hydroxyl does not complex the metal ion and is in the endo conformation. It is also likely that the aromatic ring of Phe always chelates the metal ion in a cation‐π binding configuration. Along with the amide CO and ring chelation sites, a third Lewis‐basic group almost certainly chelates the metal ion, giving a threefold chelation geometry. This third site may be either the C‐terminal carbonyl oxygen, or the N‐terminal amino nitrogen. From the spectroscopic and computational evidence, a slight preference is given to the carbonyl group, in an ROaOt chelation pattern, but coordination by the amino group is almost equally likely (particularly for K+PheAla) in an ROaNt chelation pattern, and either of these conformations, or a mixture of them, would be consistent with the present evidence. (R represents the π ring site, Oa the amide oxygen, Ot the terminal carbonyl oxygen, and Nt the terminal nitrogen.) The spectroscopic findings are in better agreement with the MPW1PW91 DFT functional calculations of the thermochemistry compared with the B3LYP functional, which seems to underestimate the importance of the cation–π interaction. 相似文献
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Back Cover: Characterization of Paramagnetic Reactive Intermediates: Predicting the NMR Spectra of Iron(IV)–Oxo Complexes by DFT (Chem. Eur. J. 37/2015)
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Dr. Andrea Borgogno Dr. Federico Rastrelli Prof. Alessandro Bagno 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(37):13140-13140
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Dr. Mathias Paul Dr. Katrin Peckelsen Thomas Thomulka Dr. Jonathan Martens Dr. Giel Berden Prof. Dr. Jos Oomens Dr. Jörg-M. Neudörfl Dr. Martin Breugst Prof. Dr. Anthony J. H. M. Meijer Prof. Dr. Mathias Schäfer Prof. Dr. Albrecht Berkessel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(8):2662-2669
Breslow intermediates (BIs) are the crucial nucleophilic amino enol intermediates formed from electrophilic aldehydes in the course of N-heterocyclic carbene (NHC)-catalyzed umpolung reactions. Both in organocatalytic and enzymatic umpolung, the question whether the Breslow intermediate exists as the nucleophilic enol or in the form of its electrophilic keto tautomer is of utmost importance for its reactivity and function. Herein, the preparation of charge-tagged Breslow intermediates/keto tautomers derived from three different types of NHCs (imidazolidin-2-ylidenes, 1,2,4-triazolin-5-ylidenes, thiazolin-2-ylidenes) and aldehydes is reported. An ammonium charge tag is introduced through the aldehyde unit or the NHC. ESI-MS IR ion spectroscopy allowed the unambiguous conclusion that in the gas phase, the imidazolidin-2-ylidene-derived BI indeed exists as a diamino enol, while both 1,2,4-triazolin-5-ylidenes and thiazolin-2-ylidenes give the keto tautomer. This result coincides with the tautomeric states observed for the BIs in solution (NMR) and in the crystalline state (XRD), and is in line with our earlier calculations on the energetics of BI keto–enol equilibria. 相似文献
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Back Cover: Understanding the Origins of Nucleophilic Hydride Reactivity of a Sodium Hydride–Iodide Composite (Chem. Eur. J. 21/2016)
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Zonghan Hong Derek Yiren Ong Dr. Subas Kumar Muduli Dr. Pei Chui Too Guo Hao Chan Dr. Ya Lin Tnay Prof. Shunsuke Chiba Dr. Yusuke Nishiyama Prof. Hajime Hirao Prof. Han Sen Soo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(21):7300-7300
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Back Cover: Activation of Elemental Sulfur at a Two‐Coordinate Platinum(0) Center (Chem. Eur. J. 36/2016)
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Dr. Sudipta Roy Christian J. Schürmann Totan Mondal Dr. Debasis Koley Dr. Regine Herbst‐Irmer Prof. Dr. Dietmar Stalke Prof. Dr. Herbert W. Roesky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(36):12944-12944
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Inside Back Cover: Intramolecular Carbolithiation of Heterosubstituted Alkynes: An Experimental and Theoretical Study (Chem. Eur. J. 22/2015)
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Dr. Rudy Lhermet Maha Ahmad Clémence Hauduc Dr. Catherine Fressigné Dr. Muriel Durandetti Dr. Jacques Maddaluno 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8299-8299
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Saad Sene Marc Reinholdt Dr. Guillaume Renaudin Dr. Dorothée Berthomieu Prof. Claudio M. Zicovich‐Wilson Prof. Christel Gervais Dr. Philippe Gaveau Prof. Christian Bonhomme Dr. Yaroslav Filinchuk Prof. Mark E. Smith Prof. Jean‐Marie Nedelec Dr. Sylvie Bégu Dr. P. Hubert Mutin Dr. Danielle Laurencin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(3):797-797
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Back Cover: Prins Cyclization Catalyzed by a FeIII/Trimethylsilyl Halide System: The Oxocarbenium Ion Pathway versus the [2+2] Cycloaddition (Chem. Eur. J. 43/2015)
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Sixto J. Pérez Dr. Martín Purino Dr. Pedro O. Miranda Prof. Víctor S. Martín Dr. Israel Fernández Dr. Juan I. Padrón 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(43):15448-15448
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Back Cover: Selective Aromatic Hydroxylation with Dioxygen and Simple Copper Imine Complexes (Chem. Eur. J. 33/2015)
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Jonathan Becker Puneet Gupta Dr. Friedrich Angersbach Prof. Dr. Felix Tuczek Prof. Dr. Christian Näther Prof. Dr. Max C. Holthausen Prof. Dr. Siegfried Schindler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(33):11908-11908
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Inside Cover: Beryllium‐Based Anion Sponges: Close Relatives of Proton Sponges (Chem. Eur. J. 51/2016)
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Oriana Brea Dr. Inés Corral Prof. Dr. Otilia Mó Prof. Dr. Manuel Yáñez Prof. Dr. Ibon Alkorta Prof. Dr. José Elguero 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(51):18270-18270
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Inside Back Cover: The Nature of Activated Non‐classical Hydrogen Bonds: A Case Study on Acetylcholinesterase–Ligand Complexes (Chem. Eur. J. 8/2016)
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Lotta Berg Dr. Brijesh Kumar Mishra Dr. C. David Andersson Dr. Fredrik Ekström Prof. Anna Linusson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(8):2831-2831