A combined experimental and theoretical study has been carried out on 4‐fluoro‐threonine, the only naturally occurring fluorinated amino acid. Fluorination of the methyl group significantly increases the conformational complexity with respect to the parent amino acid threonine. The conformational landscape has been characterized in great detail, with special attention given to the inter‐conversion pathways between different conformers. This led to the identification of 13 stable low‐energy minima. The equilibrium population of so many conformers produces a very complicated and congested rotational spectrum that could be assigned through a strategy that combines several levels of quantum chemical calculations with the principles of machine learning. Twelve conformers out of 13 could be experimentally characterized. The results obtained from the analysis of the intra‐molecular interactions can be exploited to accurately model fluorine‐substitution effects in biomolecules.
Sulfanilamide, a widely used antibacterial drug, has been brought into the gas phase using laser ablation techniques, and its structure has been characterized in the isolated conditions of a supersonic...
This work reports a complete conformational analysis of caffeic acid, an exceptionally versatile pharmacophore, using laser ablation chirped-pulse Fourier transform microwave spectroscopy.
We report a detailed structural study of cytisine, an alkaloid used to help with smoking cessation, looking forward to unveiling its role as a nicotinic agonist. Highresolution rotational spectroscopy has allowed us to characterize two different conformers exhibiting axial and equatorial arrangements of the piperidinic NH group. Unexpectedly, the axial form has been found as the predominant configuration, in contrast to that observed for related molecules, such as piperidine. This anomalous behavior has been justified in terms of an intramolecular NH•••N hydrogen bond. Moreover, this interaction justifies the overstabilization of the axial conformer over the equatorial one and is crucial for the mechanism of action of cytisine over the nicotinic receptor, further rationalizing its behavior as a nicotinic agonist.
In the present work, we report the first rotational study of N-acetylgalactosamine, a cancer-associated sugar derivative, by means of high-resolution rotational spectroscopy. Two different conformers have been conclusively characterized using broadband Fourier transform microwave spectroscopy coupled with a laser ablation vaporization system. Additionally, we performed a comprehensive analysis of the intramolecular interactions that govern these structures, which allowed us to both characterize the existence of intramolecular hydrogen bond networks that drive the intrinsic conformation panorama of N-acetylgalactosamine and further rationalize the biological role of this aminosugar derivative as part of the Tn antigen.
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