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Use of abiotic chemical systems for understanding higher order superstructures is challenging. Here we report a ring‐in‐ring(s) system comprising a hydrogen‐bonded macrocycle and cyclobis(paraquat‐o‐phenylene) tetracation (o‐Box) or cyclobis(paraquat‐p‐phenylene) tetracation (CBPQT4+, p‐Box) that assembles to construct discrete higher order structures with adaptive conformation. As indicated by mass spectrometry, computational modeling, NMR spectroscopy, and single‐crystal X‐ray diffraction analysis, this ring‐in‐ring(s) system features the box‐directed aggregation of multiple macrocycles, leading to generation of several stable species such as H4G (1 a/o‐Box) and H5G (1 a/o‐Box). Remarkably, a dimeric shish‐kebab‐like ring‐in‐rings superstructure H7G2 (1 a/o‐Box) or H8G2 (1 a/p‐Box) is formed from the coaxial stacking of two ring‐in‐rings units. The formation of such unique dimeric superstructures is attributed to the large π‐surface of this 2D planar macrocycle and the conformational variation of both host and guest. [ABSTRACT FROM AUTHOR]

Objective: Regular exercise is a powerful tool that enhances skeletal muscle mass and strength. Lysine acetylation is an important post-translational modification (PTM) involved in a broad array of cellular functions. Skeletal muscle protein contains a considerable number of lysine-acetylated (Kac) sites, so we aimed to investigate the effects of exercise-induced lysine acetylation on skeletal muscle proteins. Methods: We randomly divided 20 male C57BL/6 mice into exercise and control groups. After 6 weeks of treadmill exercise, a lysine acetylation proteomics analysis of the gastrocnemius muscles of mice was performed. Results: A total of 2,254 lysine acetylation sites in 693 protein groups were identified, among which 1,916 sites in 528 proteins were quantified. The enrichment analysis suggested that protein acetylation could influence both structural and functional muscle protein properties. Moreover, molecular docking revealed that mimicking protein deacetylation primarily influenced the interaction between substrates and enzymes. Conclusion: Exercise-induced lysine acetylation appears to be a crucial contributor to the alteration of skeletal muscle protein binding free energy, suggesting that its modulation is a potential approach for improving exercise performance. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A fuzzy-precise positioning pre-search method is presented for acceleration of compound recognition. • The spectral library pre-search space is significantly compressed in fuzzy matching stage. • The spectral library pre-search time consumption is reduced. • The spectral library pre-search accuracy is improved. Abstract A mass spectral library pre-search algorithm, fuzzy-precise positioning (FPP), is described for rapid and accurate identification of chemical compound. This algorithm works on the basis of the molecular ion feature peaks and fragment ion feature peaks of mass spectra. The algorithm mainly includes three stages: feature peaks selection, fuzzy positioning and precise positioning. For query spectra and reference spectra, four molecular ion feature peaks and six fragment ion feature peaks are selected and their corresponding mass-to-charge ratio (m/z) values are recorded, respectively. After that, fuzzy positioning is conducted to skip some unrelated spectra in the reference library by comparing maximum and minimum m/z values of feature peaks of query spectra with those of reference spectra. Finally, in the precise positioning stage, ten m/z values of feature peaks of the query spectra are matched with those of remaining reference spectra one by one. If the matching number is larger than five, this reference spectrum can be remained as a candidate spectrum. After traversing all the reference spectra remained after fuzzy positioning, final pre-search results can be obtained. To evaluate the performace of the the proposed algorithm, a series of experiments are designed by using main library and replicate library of NIST11 as reference library and query library, respectively. Moreover, real application data are used to verify the performance of FPP method. Compared to two-step spectral library pre-search (TSLP) algorithm and "ten-peak" method, the results show that FPP method can obtain higher accuracy, smaller pre-search space, shorter time consumption and less remaining spectra. [ABSTRACT FROM AUTHOR]

Abstract: A rapid, sensitive and selective UPLC/MS method using LTQ Orbitrap mass spectrometry was established for the analysis and characterization of the main biological components and their metabolites in rat plasma, urine and feces following oral administration of Lithocarpus polystachyus extract. In vivo, 22 flavonoid metabolites were observed in rat plasma, and 13 metabolites were detected in rat urine, whereas just two aglycones of dihydrochalcone (3-hydroxy phloretin and phloretin) could be detected in rat feces. Among these metabolites, one new and a known dihydrochalcone metabolite were isolated and definitely identified. Besides, five dihydrochalcone metabolites were tentatively identified as new compounds. A metabolism study of 3-hydroxyphlorizin and phloridzin was also conducted. Glucuronidation was the main metabolic pathway of phloridzin, whereas glucuronidation and sulfonation were the main metabolic pathway of 3-hydroxyphlorizin. These results provided a basis for evaluating the bioactive components of a complex natural medicine and their mechanisms of actions. [Copyright &y& Elsevier]