The conformational behavior of methyl (2-acetamido-2-deoxy-alpha-d-mannopyranosyl)phosphate 1, and its analogues, methyl C-(2-acetamido-2-deoxy-alpha-d-mannopyranosyl)methanephosphonate 2 and methyl O-(2-acetamido-2-deoxy-5a-carba-alpha-d-mannopyranosyl)phosphate , where a methylene group replaces, respectively, the anomeric and the pyranose oxygen atom, was investigated at the B3LYP/6-311+G(d,p) level [6-311+G(2df,p) for the phosphorus atom]. The energy of the optimized structures was recalculated using the continuum solvent model C-PCM choosing water as the solvent. The compounds exhibited several populated conformations, but they all showed a marked preference for the (4)C(1) geometry of the pyranose ring; this preference was almost complete for 1, very large for the phosphono analogue 2, and large for the carba analogue 3. To give experimental support to these results, compounds 2 and 3 were synthesized and characterized by NMR spectroscopy. The comparison of the theoretical and experimental vicinal coupling constants confirmed the marked preference for the (4)C(1) geometry in the case of 2 and suggested that the same holds true for compound 3.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1039/b907000a | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Reference-Based Multiple Imputation for Longitudinal Binary Data.
Stat Med
February 2025
MRC Clinical Trials Unit at UCL, University College London, London, UK.
Introduction: In clinical trials, a treatment policy strategy is often used to handle treatment nonadherence. However, estimation in this context is complicated when data are missing after treatment deviation. Reference-based multiple imputation has been developed for the analysis of a longitudinal continuous outcome in this setting.
View Article and Find Full Text PDFDecoding Anionic Organization of Hydroxide-Fluorides in a Diaspore-Type Network.
Inorg Chem
January 2025
CNRS, University of Bordeaux, Bordeaux INP, ICMCB UMR CNRS 5026, F-33600 Pessac ,France.
The diaspore-type crystalline structure is historically well-known in mineralogy, but it has also been widely studied for various applications in the field of catalysis, electrocatalysis, and batteries. However, once two anions of similar ionic size but different electronegativity, such as F and O or more precisely OH, are combined, the knowledge of the location of these two anions is of paramount importance to understand the chemical properties in relation with the generation of hydrogen bonds. Coprecipitation and hydrothermal routes were used to prepare hydroxide-fluorides that crystallize all in an orthorhombic structure with four formula units per cell.
View Article and Find Full Text PDFHA198 mutations in H9N2 avian influenza: molecular dynamics insights into receptor binding.
Front Vet Sci
January 2025
Jiangsu Agri-animal Husbandry Vocational College, Taizhou, Jiangsu, China.
Introduction: The H9N2 avian influenza virus is widely disseminated in poultry and poses a zoonotic threat, despite vaccination efforts. Mutations at residue 198 of hemagglutinin (HA) are critical for antigenic variation and receptor-binding specificity, but the underlying molecular mechanisms remain unclear. This study explores the molecular mechanisms by which mutations at the HA 198 site affect the antigenicity, receptor specificity, and binding affinity of the H9N2 virus.
View Article and Find Full Text PDFCosts and benefits of maternal nest choice: Trade-offs between brood survival and thermal stress in bees.
Ecology
January 2025
Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada.
Optimal nest site selection is crucial in animals whose offspring are completely dependent on the shelter of a nest. Parental decisions influencing nest thermal conditions are particularly important because temperature strongly influences juvenile activity, metabolism, growth, developmental rate, survival, and adult body size. In small ectotherms such as bees, maternal decisions to nest in sun-exposed or shady sites can lead to marked differences in thermal microenvironments inside nests.
View Article and Find Full Text PDFRegional and institutional trends in assessment for academic promotion.
Nature
January 2025
CancerResearch@UCC, University College Cork, Cork, Ireland.
The assessment of research performance is widely seen as a vital tool in upholding the highest standards of quality, with selection and competition believed to drive progress. Academic institutions need to take critical decisions on hiring and promotion, while facing external pressure by also being subject to research assessment. Here we present an outlook on research assessment for career progression with specific focus on promotion to full professorship, based on 314 policies from 190 academic institutions and 218 policies from 58 government agencies, covering 32 countries in the Global North and 89 countries in the Global South.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!