A new proton anisotropic-isotropic shift correlation experiment is described which operates with ultrafast MAS, resulting in good resolution of isotropic proton shifts in the detection dimension. The new experiment makes use of a recoupling sequence designed using symmetry principles which reintroduces the proton chemical shift anisotropy in the indirect dimension. The experiment has been used to measure the proton shift tensor parameters for the OH hydrogen-bonded protons in tyrosine·HCl and citric acid at Larmor frequencies of up to 850 MHz.
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http://dx.doi.org/10.1016/j.jmr.2013.07.005 | DOI Listing |
J Chem Theory Comput
January 2025
Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, United States.
Despite its importance in understanding biology and computer-aided drug discovery, the accurate prediction of protein ionization states remains a formidable challenge. Physics-based approaches struggle to capture the small, competing contributions in the complex protein environment, while machine learning (ML) is hampered by the scarcity of experimental data. Here, we report the development of p ML (KaML) models based on decision trees and graph attention networks (GAT), exploiting physicochemical understanding and a new experiment p database (PKAD-3) enriched with highly shifted p's.
View Article and Find Full Text PDFOrg Biomol Chem
January 2025
Department of Chemistry, IIT Bombay, Powai, Mumbai 400076, India.
[16]Thiatriphyrin(2.2.1)s containing one thiophene and two pyrroles connected five -carbons were synthesized by condensing a new precursor, -fused thiatripyrrane, with an appropriate aryl aldehyde in CHCl under acid-catalyzed inert conditions followed by open air oxidation with DDQ.
View Article and Find Full Text PDFJ Pharm Sci
January 2025
Drug Delivery and Disposition, KU Leuven, Department of Pharmaceutical and Pharmacological Sciences, Campus Gasthuisberg ON2, Herestraat 49 b921, 3000 Leuven, Belgium. Electronic address:
In order to evaluate the stability of an amorphous solid dispersion (ASD) it is crucial to be able to accurately determine whether the ASD components are homogeneously mixed or not. Several solid-state analysis techniques are at the disposal of the formulation scientist, such as for example modulated differential scanning calorimetry (mDSC) and solid-state nuclear magnetic resonance spectroscopy (ssNMR). ssNMR is a robust, versatile, and accurate analysis technique with a large number of application possibilities.
View Article and Find Full Text PDFPhysiol Plant
January 2025
College of Life Sciences, Nanjing Agricultural University, Nanjing, China.
Phosphorus (P) deficiency is a critical factor limiting crop productivity, primarily due to its detrimental effects on photosynthesis and dry matter accumulation. In this study, we investigate the role of the rice gene OsPHT2;1 in mediating chloroplast P homeostasis and its subsequent impact on photosynthetic function under low P conditions. Stomatal conductance is typically positively correlated with net photosynthetic rates; however, P deficiency disrupts this relationship, leading to reduced stomatal opening and diminished photosynthetic efficiency.
View Article and Find Full Text PDFUnlabelled: Proton exchange is a fundamental chemical event, and NMR provides the most direct readout of protonation events with site-specific resolution. Conventional approaches require manual titration of sample pH to collect a series of NMR spectra at different pH values. This requires extensive sample handling and often results in significant sample loss, leading to reduced signal or the need to prepare additional samples.
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