Use of Catalyst in a 3D-QSAR study of the interactions between flavour compounds and beta-lactoglobulin

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3D-QSAR study of ligands for a human olfactory receptor

Abstract Only about 350 olfactory receptors (OR) provide a basis for the remarkable ability of humans to recognise and discriminate a large number of odorants. A recent study reports the odorant repertoire of a human class II OR called OR1G1, including both agonists and antagonists. We used these affinity data to perform a 3D molecular modelling study of these ligands using Catalyst/HypoGen software (Catalyst v4.9.1, Accelrys Inc., San Diego, 2004) to propose alignment models for OR1G1 ligands. We obtained a triple-alignment model, which satisfactorily explained the experimental activities and was able both to predict the antagonist effects of some compounds and to identify new potent agoni…

In vivo high-throughput identification of olfactory receptor repertoire coding for a blending mixture

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Aspects chimiques et physico-chimiques des relations structure-activité : synthèse peptidique de mimes de sites protéiques et études de la morphologie et de la réactivité d'interfaces solide-liquide

In silico study of correspondences between odors descriptions linked to common features of aromas compounds

The first step of odor detection and discrimination of structurally diverse odorants depends of their interactions with olfactory receptors (ORs) [1], whereas the perception of odors quality results from a combinatorial coding [2], whose identification still remains a major challenge. Recently, Martinez-Mayorga et al. demonstrated that odor description can be successfully analyzed using a metric approach by performing a descriptive analysis of the Flavor Base database (http://www.leffingwell.com, version 2010) [3]. The current version Flavor Base (9th edition, 2013) is one of the largest collections of flavor molecules (4226 molecules). We extracted 3508 molecules for which the described od…

Proposed alternative phase ratio variation method for the calculation of liquid–vapour partition coefficients of volatiles

International audience; The phase ratio variation PRV method is a classical way to determine the partition coefficients of volatile compounds between their solution and vapour phases in a variety of circumstances. However, some results obtained by this method can be disappointing. A new PRV equation in which the initial liquid-phase solute concentration is replaced by the liquid-phase solute concentration at equilibrium is proposed. This proposed PRV equation is a second-order polynomial equation. To thoroughly examine the possible modes of calculation, noisy dummy data were generated using both the classical, first-order PRV model (PRV1) and the proposed, second-order model (PRV2). Thus, p…

Formation des agrégats à partir d'une phase cristalline d'acide orthoborique. Intérêt pour la technologie des poudres pharmaceutiques

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Exploring subtle molecular interactions involved between aroma compounds and food matrices/mediums using QSPR approach

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2D- and 3D-QSAR Models of Interaction between Flavor Compounds and beta-Lactoglobulin Using Catalyst and Cerius2

The present paper describes an application of Catalyst to three aroma sets (35, 24 and 21 compounds respectively) to generate activities-based alignments, using the best significant generated hypotheses. The obtained Catalyst models confirmed the existence of at least two binding sites on the BLG.

Ligand binding study revealing a human olfactory receptor involved in waxy-floral odor perception

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Les molécules odorantes, sapides et trigéminales

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Prediction of perception using structure–activity models

IntroductionThe possible link between the molecular structure and a biological activity was pointed out by Linus Pauling (1946) just before the middle of the 20th century. Nevertheless, this concept has been already suggested a century before by Emil Fisher and “lock-and-key” theory: “To use a metaphor, I would say that enzyme and glucoside are such lock and key that fit together in order to exert a reciprocal chemical effect on each other”a (Fischer, 1894). The notion that the biological properties of a compound would be a function of its chemical characteristics is now well admitted, and is closely linked to that of pharmacophore. The pharmacophore concept is related to the interaction of…

Quantitative structure-property relationships approach of aroma compounds behaviour in polysaccharide gels

International audience; Pectin and carrageenan are common used thickeners in fat free foods. The aim of this work was to study separately and to compare their respective effects on the aroma release, in order to investigate the nature of involved interactions. In this way, we studied the influence of the chemical structure of 13 aroma compounds on retention/release equilibrium between vapour phase and gels using QSPR tools. Six descriptors are involved in the best obtained QSPR equations, and three of them appeared to play a critical role in the behaviour of aroma compound. Our results put forward the role of polar effects on the retention of odorant molecules in both iota-carrageenan and p…

QSAR/QSPR approach of aroma compounds behaviour in food products

National audience; Fat and flavour are important factors in food acceptance and can affect the partitioning of hydrophobic flavour molecules. Most investigations on the release of flavour of fat-free yoghurts contain multiple thickeners. The addition of thickeners separately to fat-free yoghurt has not been extensively studied. For this reason, the aim of this work was to study the effects of different thickeners (starch and pectin) on the aroma release when added separately via a model fruit preparation to industrial fat-free yoghurt. After aromatisation of the yoghurt, and then a seven-day storage period, headspace analysis using solid phase micro extraction (SPME) was carried out. To eva…

Récepteurs olfactifs, modélisation et psychophysique... vers la compréhension du codage qualitatif des odeurs

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3D-QSAR study of ligands for two human olfactory receptors

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Les récepteurs olfactifs et le codage des odeurs

The first step of the olfactory detection involves the activation by odorants of olfactory receptors, which are membrane proteins embedded in the membrane of olfactory neurons. Odour coding results from the combinatory activation of a set of receptors and rests on their clonal expression. Neuronal olfactory connexion leads to the formation, in the cortex, of a specific sensory map, which gives rise to the odor perception. This combinatorial system allows, with approximately 340 different receptors, to discriminate myriads of odorants that are natural or not (new cooking flavours, synthetic chemicals…). The extreme olfactory genome diversity in human beings may explain different food behavio…

Flavor Release from i-Carrageenan Matrix: A Quantitative Structure-Property Relationships Approach

International audience; We carried out a QSPR (quantitative structure-property relationships) approach to evaluate the influence of the chemical structure of aqueous matrixes over the partition coefficient between the gas phase and the matrix. The determination of the partition coefficient of flavor ingredients was performed by headspace analysis at equilibrium for both saline solution and -carrageenan gel. Starting from an initial list of 90 descriptors, we selected 10 descriptors to perform equation generation by the GFA (genetic function approximation) method available in the Cerius2 package. The best obtained equations involve only five descriptors, which encode electronic properties of…

Odour perception: A review of an intricate signalling pathway

The perception of odours is the result of the complex processing of a signal, which initiates at peripheral receptors and ends in the brain. Along this pathway, olfactory signal processing proceeds through several steps; each step possesses its own complexity, and all steps are also intricately connected. This review aims to describe the main intricate steps of olfactory processing in mammals, some of which remain unclear, and the close associations and overlapping nature of these steps. The causes of both the complexity and the variability of olfactory signals are examined: the nature of olfactory receptors, involving the diversity of the genome; the spatial organization of the olfactory e…

Multivariate statistical analysis of a large odorants database aimed at revealing similarities and links between odorants and odors

International audience; The perception of odor is an important component of smell; the first step of odor detection, and the discrimination of structurally diverse odorants depends on their interactions with olfactory receptors (ORs). Indeed, the perception of an odor's quality results from a combinatorial coding, in which the deciphering remains a major challenge. Several studies have successfully established links between odors and odorants by categorizing and classifying data. Hence, the categorization of odors appears to be a promising way to manage odors. In the proposed study, we performed a computational analysis using odor descriptions of the odorants present in Flavor-Base 9th Edit…

[P27] Chemo-Biological Analysis Applied to the Olfaction Field

Human are surrounded by numerous odorant molecules in the air from a limited number of olfactory receptors (1), and the odor perceived from these molecules does not comes from the isolated molecules but from their mixture (2). According to the odor perceived from the mixture, we differentiate the heterogeneous perception which is the distinction between the odor components of the mixture and the homogeneous perception that corresponds to the perception of a single odor from the mixture preventing the distinction between odor components of the mixture. There are two types of homogeneous perceptions: the masking and the blending mixture. Masking occurs when one of the mixture components cover…

Retention and release behaviours of aroma compounds in dairy and pectin gels: the role of structural features

An olfactory receptor detects waxy, fatty and rose odors

An olfactory receptor detects waxy, fatty and rose odors. Salon Européen de la Recherche et de l’Innovation

[P32] Study of Odorants Sharing the Odor Notes of an Aroma Blending Mixture by a Pharmacophore Approach

Odors perceived in our environment are mainly the result of mixtures of odorants whose the specific mechanisms involved in their processing remain poorly understood [1]. In previous studies performed at INRAE-CSGA [2], the perception of a mixture of ethyl isobutyrate (Et-iB, strawberry-like odor, STR) and ethyl maltol (Et-M, caramel-like odor, CAR) was investigated in comparison with a reference (allyl hexanoate, Al-H, pineapple-like odor, PNA) chosen to evoke an odor close to the one expected in the mixture. The binary specific mixture of Et-iB and Et-M was judged as more typical of a pineapple odor than the individual components. Some studies highlight the significance of the biological f…

Predicting multi-functionality of bitter taste compounds using computational tools

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Exploring the network of odours shared by an aroma blending mixture

International audience; The first step of odour perception is an interaction between odorants and olfactory receptors [1]. Moreover, odours perceived in our environment are mainly the result of mixtures of odorants; however, the specific mechanisms involved in their processing remain poorly understood [2]. In previous studies performed at INRA-CSGA [3], the perception of a mixture of ethyl isobutyrate (Et-iB, strawberry-like odour, STR) and ethyl maltol (Et-M, caramel-like odour, CAR) was investigated in comparison with a reference (allyl hexanoate, Al-H, pineapple-like odour, PNA) chosen to evoke an odour close to the one expected in the mixture. The binary specific mixture of Et-iB and Et…

Improvement of partition coefficients determination of aroma compounds in food matrices by the phase ratio variation method

The Phase Ratio Variation (PRV) method is a very valuable method commonly used for liquid/vapor partition coefficients data acquisition of aroma compounds. Nevertheless, some limits are linked to this method, especially for volatile compounds. A careful examination of the PRV equation leads us to propose the following expression: 1/Cvap-real =(nliq/n0) x 1/Cvap-ideal = (nliq/n0) x (1/KC0 + (1/Co) b), We performed an examination for two cases of K values (K1=0.001 and K2=0.05), putting forward that a carefully choice of b range values is crucial for reliability of the regression calculation 1/A versus b.

Study of Morphology of Reactive Dissolution Interface Using Fractal Geometry

J. Pharm. Sci. ISI Document Delivery No.: VF662 Times Cited: 7 Cited Reference Count: 15 Tromelin, A Gnanou, JC Andres, C Pourcelot, Y Chaillot, B; International audience; The determination of reactive fractal dimension was carried out using two forms of the Noyes-Whitney equation, -dQ/dt = K(Q/Q(0))(DR/3) and -d Q/dt = K' R(DR-3) using the Richardson plot on the basis of previous data obtained by dissolution of an orthoboric acid powder. The correlation of the results provided by the two ways of calculation allows proposal of the hypothesis that dissolution begins on a specific population of reactive sites and probably promotes the formation of microporous volumes or cracks.

Evidence for interactions between aroma compounds and the CB1 receptor: a way to regulate food intake?

National audience; Obesity is a major cause of morbidity and mortality worldwide, characterised by a chronic imbalance of energy homeostasis. The regulation of dietary intake appears to be an effective way to regulate this imbalance. Furthermore, it is now well established that the endocannabinoid system influences appetite via the cannabinoid receptor type 1 (CB1): CB1 agonists can promote food intake while CB1 antagonists tend to decrease appetite (1). Interestingly, recent studies showed that CB1-like receptors are expressed in the olfactory epithelium of Xenopus laevis tadpoles (2). Elsewhere, it has been demonstrated that aroma perception is implicated in the process of satiety (3). Co…

Aroma release in fat free dairy gels added or not added with pectin

International audience; The replacement of fat by thickeners in fat free yogurts leads to an important modification of aroma compounds partitioning, with an impact on aroma perception (Guichard, 2002). Investigation of retention/release equilibriums allows a good understanding of aroma compounds behaviour depending on food composition. The aim of this work is to study the influence of matrix composition on aroma release.

3d ligandbased virtual screening for deorphanisation of a human olfactory receptor

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2D- and 3D-QSAR models of interaction between flavor compounds and beta-lactoglobulin using catalyst and cerius

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Etude de la morphologie de l'interface reactive de dissolution en utilisant le concept de géométrie fractale

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Exemples de QSAR sur des coefficients de partage

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Molécules odorantes : olfaction, prise alimentaire, activité biologique

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Does saliva modify the volatility of aroma compounds?

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Influence of the parameters molecular structure and granularity on the compactibility of a powder

Drug Dev. Ind. Pharm. ISI Document Delivery No.: RP128 Times Cited: 3 Cited Reference Count: 14 Andres, c ndiaye, a thomas, c tromelin, a chaillot, b pourcelot, y; International audience; The aim of this study was to determine whether it is possible to obtain better characterization of materials in order to find out if these one are suitable in Quality Assurance for direct tableting. We tried to show that a methodological approach combining chemical, physical and technological aspects could control the direct compression process. We chose orthoboric acid as a study model for the direct compression. From a chemical point of view, our findings show only one crystalline molecular structure (RX…

Could aroma compounds interact with the endocannabinoid system?

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Evidence of interactions between aroma compounds and the CB1 receptor opens new routes for regulation of food intake

Retention-release equilibrium of aroma compounds in polysaccharide gels: study by quantitative structure-activity/property relationships approach

The nature and amount of constituents in food greatly influence aroma release. Pectins and carrageenans are common used thickeners, but their effect on the release of aroma compounds has been studied more frequently for non- homogeneous products than for thickeners separately. The purpose of this work was to study and compare their respective effects in simple model systems. In this way, the release of 13 aroma compounds was analysed by headspace analysis at equilibrium in pure water, i-carrageenan and pectin gels. To evaluate the influence of the chemical structure of aroma com- pounds on retention/release equilibrium between vapour phase and gels, we used a quantitative structure-activity…

In silico approach to identify odor metric using odor descriptions

International audience

Impact of structural features of odorant molecules on their retention/release behaviours in dairy and pectin gels

International audience; Reducing of fat content in food requires a reformulation that may cause a different perception of aroma. Maintaining an adequate level of acceptability of these reformulated products for consumers requires a better understanding of the mechanisms that control the retention of odorant molecules in food matrices. Although pectins are commonly employed as thickeners, their effect on the retention of odorant molecules in nonhomogeneous products has been examined more frequently than their effect on the retention of odorant molecules in simple gels models.The purpose of this study was to explore and compare the respective effects of pectin in simple model systems. The rel…

Nuclear magnetic resonance spectroscopic study of beta-lactoglobulin interactions with two flavor compounds, gamma-decalactone and beta-ionone.

Interactions between a well-characterized protein, beta-lactoglobulin, and two flavor compounds, beta-ionone and gamma-decalactone, were studied by 2D NMR spectroscopy. NMR spectra were recorded in aqueous solution (pH 2.0, 12 mM NaCl, 10% D(2)O) under conditions such that beta-lactoglobulin is present in a monomeric state. TOCSY and NOESY spectra were recorded on the protein and the complexes between protein and ligands. The spectra of the NH-CH(alpha) region showed the cross-signals due to the coupling between N- and C-bonded protons in the polypeptide backbone. The observed chemical shift variations in the presence of ligands can be assigned to changes in the protein conformation. It app…

Increasing knowledge of odors and molecular structures linkages of smell compounds by comparing UMAP method to other classification approaches

International audience; The olfactory perception begins at the olfactory epithelium level with the activation of olfactory receptors (ORs) by the binding of odorants1. The olfactory system can discriminate a huge number of odors that would reach 1 trillion2. Odor structure relationships in olfaction is a challenging area and a key element in understanding the olfactory system3-5. This study aims to highlight the relationships between the structure of smell compounds and their odors. For this purpose, 6038 odorant compounds and their known associated odors (162 odor notes) were compiled. We assessed four dimensional reduction techniques (PCA, MDS, t-SNE and UMAP6) and two clustering methods …

Chemo-biological analysis applied to the olfaction field

Human are surrounded by numerous molecules in the air from a limited number of olfactory receptors [1], and one odor is not caused by only one compound but by a mixture of molecules [2]. Two different perceptions exist, the first being the heterogeneous perception which is the distinction between the odor components of the mixture. The second perception is homogeneous and consists in a mixture of molecules resulting in a single odor which is not possible to distinguish between odor components of the mixture. There are two types of homogeneous perceptions:1-When one of the mixture components covers the other constituents and we can only smell the odor of one of the mixture components: it is …

Multidisciplinary approach to explore interactions in odor mixture perception

Odors and aromas perceived in food and in the environment result from the processing of complex chemical mixtures of volatile compounds that should be efficiently processed by the olfactory system. It is known for decades that this processing generates perceptual interactions, such as masking, synergy, or perceptual blending, which contribute to elaborating a synthetic brain representation of the chemical information. Nevertheless, the perceptual processes underlying these interactions are still poorly known. In this project, we set out a multidisciplinary approach to identify the characteristics of odorants and olfactory receptors (ORs) that could support perceptual interactions. We hypoth…

Perceptual interactions in mixtures of odorants

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Exploring subtle molecular interactions involved between aroma compounds and food mediums using QSPR approach

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A human olfactory receptor for waxy, fatty and rose odors

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New determinants of olfactory habituation

AbstractHabituation is a filter that optimizes the processing of information by our brain in all sensory modalities. It results in an unconscious reduced responsiveness to continuous or repetitive stimulation. In olfaction, the main question is whether habituation works the same way for any odorant or whether we habituate differently to each odorant? In particular, whether chemical, physical or perceptual cues can limit or increase habituation. To test this, the odour intensity of 32 odorants differing in physicochemical characteristics was rated by 58 participants continuously during 120s. Each odorant was delivered at a constant concentration. Results showed odorants differed significantl…

Exploring the odorant and molecular characteristics of molecules sharing the odour notes of an aroma blending mixture

Online event (Live and on-demand); International audience; To perceive a huge number of odors from few hundreds ORs, the human olfactory system encodes odor identities by an olfactory scheme whereby one olfactory receptor (OR) recognizes multiple odorants while one odorant activates different combinations of ORs [1, 2]. Odors perceived in our environment are mainly the result of mixtures of odorants, but the specific mechanisms involved in their processing remain poorly understood [3]. In previous studies performed at INRAE-CSGA [4], the perception of a mixture of ethyl isobutyrate (Et iB, strawberry-like odor, STR) and ethyl maltol (Et-M, caramel-like odor, CAR) was investigated in compari…

Interaction between flavour compounds and beta-lactoglobulin: approach by NMR and 2D/3D-QSAR studies of ligands

 author cannot archive publisher's version/PDF; International audience; Interactions between flavour compounds and beta-lactoglobulin (BLG) have been the subject of several studies, but there are no unanimous binding site explanations. In our laboratory, interactions between BLG, and two flavour compounds, beta-ionone and gamma-decalactone, were studied by 2D-NMR spectroscopy. It appears that several amino acids affected by binding of gamma-decalactone are buried in the central cavity, whereas binding of beta-ionone affects amino acids located in a groove near the outer surface of the protein. 2D/3D-QSAR studies were performed using QSAR+ module of Cerius2 and Catalyst. The QSAR equation pr…

How properties of aroma compounds could be explained by molecular properties?

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Disease sytems chemical biology of flavors

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Use of Catalyst in a 3D-QSAR Study of the Interactions between Flavor Compounds and β-Lactoglobulin

This paper reports a 3D-QSAR study using Catalyst software to explain the nature of interactions between flavor compounds and beta-lactoglobulin. A set of 35 compounds, for which dissociation constants were previously determined by affinity chromatography, was chosen. The set was divided into three subsets. An automated hypothesis generation, using HypoGen software, produced a model that made a valuable estimation of affinity and provided an explanation for the lack of correlation previously observed between the hydrophobicity of terpenes and the affinity for the protein. On the basis of these results, it appears that aroma binding to beta-lactoglobulin is caused by both hydrophobic interac…

Retention/release equilibrium of aroma compounds in fat-free dairy gels

BACKGROUND: The replacement of fat by thickeners in fat-free yoghurts leads to an important modification of aroma compound partitioning, with an impact on aroma perception. Investigation of retention/release equilibria allows a good understanding of aroma compound behaviour depending on food composition. RESULTS: Vapour/liquid equilibria of ten aroma compounds (two esters, two ketones, three aldehydes and three alcohols) in several media were studied to investigate the influence of pectin addition to fat-free dairy gel on the retention/release equilibrium. The partition coefficient of each aroma compound was measured by headspace analysis at equilibrium in six media (pure water, low-methoxy…

Nuclear magnetic resonance spectroscopic study of beta-lactoglobulin interactions with two flavor compounds, gamma-decalactone and beta-ionone

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Identification of aroma compounds as novel CB1 receptor ligands via in silico approaches

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Use of fractal geometry to dissolution study of a sweetener excipient

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Aptitude à la comprimabilité : structure moléculaire - état particulaire

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Towards an understanding of odor blending in odorant mixtures: a pharmacophore approach

National audience; Odors we perceived in our environment are mainly the result of mixtures of odorants. The first step of odor perception is an interaction between these odorant mixtures and olfactory receptors. The corresponding transduced olfactory signals, conveyed by olfactory sensory neurons, are then processed by the brain (Zou et al. 2006). In previous studies, we investigated the perception of a mixture including specific proportions of ethyl isobutyrate (strawberry-like odor) and ethylmaltol (caramel-like odor). This specific mixture was especially judged as more typical of a pineapple odor than the individual components (Coureaud et al. 2008, Le Berre et al. 2008, Coureaud et al. …

Physical and chemical interactions involved in several flavour compounds/food matrix systems

National audience; Food-matrix components, such as proteins, polysaccharides, and lipids interact with flavour compounds in different ways. Proteins bind flavour compounds mostly by hydrophobic interactions and possible hydrogen bonding, as illustrated by molecular visualisation. Addition of fat induces a great retention of hydrophobic compounds, which depend on the nature of fat, degree of unsaturation, hydrophobic chain length of fatty acids. Addition of hydrocolloids modifies the release of hydrophobic aroma compounds, due to a lower diffusion in the matrix. In jellified systems, gel structure not only affects partition coefficients but also mass transfer coefficients of flavour compound…

Relationship between particle size and dissolution rate of bulk powders and sieving characterized fractions of two qualities of orthoboric acid

Drug Dev. Ind. Pharm. ISI Document Delivery No.: VN279 Times Cited: 1 Cited Reference Count: 22 Tromelin, A Habillon, S Andres, C Pourcelot, Y Chaillot, B; International audience; We have carried out a study of the particle size distribution and aqueous dissolution rate of two commercially available qualities of orthoboric acid, labeled ''crystal'' (ABC) and ''powder'' (ABP). In a previous work, we have shown that the two commercial qualities of orthoboric acid chosen as model compound (''powder'' and ''crystal'') are related to the same crystal network in spite of their different names. However, these two qualities have very different size particle distributions, as previously determined b…

Application de l'approche QSAR/QSPR à la perception des arômes

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Développement d’une méthode d’analyse de la désorption de composés d’arôme par PTR-MS sur un modèle in vitro de muqueuse orale

Développement d’une méthode d’analyse de la désorption de composés d’arôme par PTR-MS sur un modèle in vitro de muqueuse orale. Congrès français de Spectrométrie de Masse et d'Analyse Protéomique (SMAP 2015)

Effect of calculation methods and presence of false positives on perception thresholds

Perception thresholds are commonly used in food science to discriminate between those compounds that are more or less odour-active. It is not rare to use values from other studies and apply them to our data, however, we observed that the procedure to evaluate and calculate perception thresholds is not standardised. The aim of this study was to explore the influence of calculation methods on threshold values. To do so, we used a 3-AFC sensory procedure to determine the orthonasal and retronasal detection values of 26 compounds, amongst them some compounds that usually contribute to the aroma of strawberry and caramel (e.g. vanillin, Furaneol and damascenone). The thresholds were calculated b…

Cannabinoid ligands sorting out by a 3D-QSAR approach using catalyst/hypogen

National audience; Understanding how molecular structures are involved in recognition by a biological receptor is a decisive step in drug design, and could constitute an intricate problem because of existence of several binding sites, as is the case of GPCRs (1) that constitute the largest class of membrane receptors. In this context, identification of pharmacophores that should differentiate multiple binding modes is of particular interest. We have recently applied to ligands of a human olfactory receptor an original sorting-out procedure carried out using Catalyst/HypoGen software (Accelrys Ltd) (2). We aimed to validate this sorting out procedure using literature data, and in this way, w…

3D-QSAR study of ligands for two human olfactory receptors

International audience; All living organisms, including human beings, are able to detect and discriminate myriads of structurally diverse odorants through their interaction with olfactory receptors (ORs) (1). It is well accepted that the perception of thousands of odors by about 380 ORs results from a combinatorial coding, in which one OR recognizes multiple odorants and different odorants are recognized by different combinations of ORs (2). In a previous study (3), the functional characterization on two human ORs, called OR1G1 (class II) and OR52D1 (class I) have been performed using 95 odorant molecules. We used these previously obtained functional data (3) to perform a molecular modellin…