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In this article, we review studies of the protagonists of the perception of smell focusing on Odorant-Binding Proteins and Olfactory Receptors. We notably put forward studies performed by means of molecular modeling, generally combined with experimental data. Those works clearly emphasize that computational approaches are now a force to reckon with. In the future, they will certainly be more and more used, notably in the framework of a computational microscope meant to observe how the laws of physics govern the biomolecular systems originating our sense of smell. [ABSTRACT FROM AUTHOR]

Abstract: The dynamic behaviour analysis of porcine OBP, free of ligand, and complexed with 2-isobutyl-3-methoxypyrazine and 2,6-dimethyl-7-octen-2-ol has been performed by means of molecular dynamics simulations. The simulations reveal that the OBP cavity, while being hydrophobic, is likely to produce hydrophilic interactions with some of the internal residues. A large evolution of the OBP cavity volume has been observed, ranging between 400 and 800Å3 independently of the ligand buried into the cavity. The hydrophobic cavity is shielded from the solvent, but openings have been observed, triggered by shifts of residues considered to constitute the door of the cavity, especially tyrosine 82. [Copyright &y& Elsevier]

Abstract: DFT investigations of the acid-catalysed oxidation of linear and cyclic epoxides by DMSO revealed that a first step of nucleophilic ring-opening is followed by two different reaction pathways: on one hand α-hydroxycarbonyl derivatives are formed, via oxidative ring-opening, and on the other hand two aldehyde moieties are obtained, via oxidative cleavage. Calculations with the polarized continuum method (PCM) taking into account the DMSO solvation effect did not significantly change the energy barriers. [Copyright &y& Elsevier]

Based on the most exhaustive database of sweeteners with known sweetness values, a new quantitative structure-activity relationship model for sweetness prediction has been set up. Analysis of the physico-chemical properties of sweeteners in the database indicates that the structure of most potent sweeteners combines a hydrophobic scaffold functionalized by a limited number of hydrogen bond sites (less than 4 hydrogen bond donors and 10 acceptors), with a moderate molecular weight ranging from 350 to 450 g·mol −1 . Prediction of sweetness, bitterness and toxicity properties of the largest database of natural compounds have been performed. In silico screening reveals that the majority of the predicted natural intense sweeteners comprise saponin or stevioside scaffolds. The model highlights that their sweetness potency is comparable to known natural sweeteners. The identified compounds provide a rational basis to initiate the design and chemosensory analysis of new low-calorie sweeteners. [ABSTRACT FROM AUTHOR]

G protein--coupled olfactory receptors (ORs) enable us to detect innumerous odorants. They are also ectopically expressed in nonolfactory tissues and emerging as attractive drug targets. ORs can be promiscuous or highly specific, which is part of a larger mechanism for odor discrimination. Here, we demonstrate that the OR extracellular loop 2 (ECL2) plays critical roles in OR promiscuity and specificity. Using site-directed mutagenesis and molecular modeling, we constructed 3D OR models in which ECL2 forms a lid over the orthosteric pocket. We demonstrate using molecular dynamics simulations that ECL2 controls the shape and volume of the odorant-binding pocket, maintains the pocket hydrophobicity, and acts as a gatekeeper of odorant binding. Therefore, we propose the interplay between the specific orthosteric pocket and the variable, less specific ECL2 controls OR specificity and promiscuity. Furthermore, the 3D models created here enabled virtual screening of new OR agonists and antagonists, which exhibited a 70% hit rate in cell assays. Our approach can potentially be generalized to structure-based ligand screening for other G protein--coupled receptors that lack high-resolution 3D structures. [ABSTRACT FROM AUTHOR]

Abstract: Triphosphates anabolites are the active chemical species of nucleosidic reverse transcriptase inhibitors in HIV-therapy. Herein, we describe (i) the design of stable triphosphate analogues of AZT using molecular modelling, (ii) their synthesis and (iii) their use for producing anti AZT-TP antibodies in the aim of developing an immunoassay for therapeutic drug monitoring. [Copyright &y& Elsevier]