A novel, to our knowledge, in situ photoirradiation system for solid-state NMR measurements is improved and demonstrated to successfully identify the M-photointermediate of pharaonis phoborhodopsin (ppR or sensory rhodopsin II), that of the complex with transducer (ppR/pHtrII), and T204A mutant embedded in a model membrane. The (13)C NMR signals from [20-(13)C]retinal-ppR and ppR/pHtrII revealed that multiple M-intermediates with 13-cis, 15-anti retinal configuration coexisted under the continuously photoirradiated condition. NMR signals observed from the photoactivated retinal provide insights into the process of photocycle in the ppR/pHtrII complex.
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http://dx.doi.org/10.1016/j.bpj.2011.10.022 | DOI Listing |
J Biomol NMR
January 2025
Research Unit Molecular Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert- Rössle-Straße 10, 13125, Berlin, Germany.
Chemical shift assignments of large membrane proteins by solid-state NMR experiments are challenging. Recent advancements in sensitivity-enhanced pulse sequences, have made it feasible to acquire H-detected 4D spectra of these challenging protein samples within reasonable timeframes. However, obtaining unambiguous assignments remains difficult without access to side-chain chemical shifts.
View Article and Find Full Text PDFJ Phys Chem C Nanomater Interfaces
January 2025
Center for Materials Science and Nanotechnology (SMN), Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, Oslo N-0315, Norway.
The flexibility of the H-ZSM-5 zeolite upon adsorption of selected coke precursors was investigated using both theoretical and experimental approaches. Four structural models with varying active site locations were analyzed through density functional theory (DFT) simulations to determine their responses to different types and quantities of aromatic molecules. Complementary experimental analysis was performed, allowing for a direct comparison with the theoretical findings, using thermogravimetric analysis (TGA), nitrogen adsorption (N adsorption), solid-state NMR, and X-ray diffraction (XRD).
View Article and Find Full Text PDFJ Nat Prod
January 2025
Department of Chemistry and Biological Engineering, Graduate School of Science and Engineering, Yamagata University, Yonezawa, Yamagata 992-8510, Japan.
We investigated the chemical structures and conformational isomers of the cyclic heptapeptides stylissamide H and euryjanicin A isolated from marine sources. Despite sharing the same molecular structure, stylissamide H and euryjanicin A exhibit different conformational isomers in solution and solid states. The main difference arises from the configurations of the two Pro residues.
View Article and Find Full Text PDFAdv Mater
January 2025
Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany.
The rapid advancement of covalent organic frameworks (COFs) in recent years has firmly established them as a new class of molecularly precise and highly tuneable porous materials. However, compared to other porous materials, such as zeolites and metal-organic frameworks, the successful integration of hierarchical porosity into COFs remains largely unexplored. The challenge lies in identifying appropriate synthetic methods to introduce secondary pores without compromising the intrinsic structural porosity of COFs.
View Article and Find Full Text PDFChemistry
January 2025
Universidad de Zaragoza, Química Física, SPAIN.
The 18e saturated rhodium(III) species [Rh(H)(X)(κ2-NSitBu2)(bipyMe2)] (NSitBu2 = {4-methylpyridine-2-yloxy}ditertbutylsilyl; bipyMe2 = 4,4´-dimethylbipyridine) (X = Cl, 1; OTf, 2) have been prepared and characterized by NMR spectroscopy and in the case of 2 it has been possible to determine its solid-state structure by X-ray diffraction. Complex 1 has proven to be an effective catalyst precursor for the reaction of styrene derivatives with hydrosilanes in CD2Cl2. However, under catalytic conditions complex 2 decomposes.
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