Purine 5’-ribonucleotide-glutamate hybrids as potential tools to investigate the mechanism of umami taste reception

Rabuffetti, M.; Brockhoff, A.; Morelli, C.; Sangiorgio, S.; Scarabattoli, L.; Pappalardo, V.; Pieraccini, S.; Sironi, M.; Speranza, G.

Umami taste is elicited predominantly by the presence of L-glutamate and purine 5’-ribonucleotides, in particular guanosine and inosine 5’-monophosphates. A significant peculiarity of umami compounds is their capacity to interact synergistically.[1] A possible explanation of such phenomenon at a molecular level is that both L-glutamate and ribonucleotides may interact simultaneously with the extracellular “Venus flytrap” (VFT) domain of the umami receptor (a heteromeric complex of two class C G protein-coupled receptors, T1R1 and T1R3), but at different sites.[2] Starting from this model, we reasoned that hybrid compounds, containing the two umami moieties covalently connected through flexible linkers of variable length, could be able to reach both umami receptor sites through a single molecule, thus giving a further insight into the mechanism of synergism. Molecular Dynamics simulations performed on the homology model of the VFT domain suggested that a chain of at least eight carbon atoms is requested to allow the interaction of both glutamate and 5’-ribonucleotide with their respective binding sites. We present here the synthesis of purine 5’-ribonucleotide-glutamate hybrids 3 and 4, characterized by long flexible linkers consisting of eight and ten carbon atoms, respectively, as well as of hybrids 1 and 2, characterized by shorter chains and used as negative controls. Key step in the synthetic route was the activation of the 2-position of the purine ring as a 2-bromo derivative, followed by substitution with the proper diamines. All umami hybrids were tested with the functionally expressed T1R1/T1R3 umami receptor in a cell-based assay.[3] References [1] W. Wang, X. Zhou, Y. Liu, Trends Anal. Chem. 2020, 127, 115876 [2] F. Zhang, B. Klebansky, R. M. Fine, H. Xu, A. Pronin, H. Liu, C. Tachdjian, X. Li, PNAS 2008, 105, 20930-20934 [3] B. Suess, A. Brockhoff, A. Degenhardt, S. Billmayer, W.Meyerhof, T. Hofmann, J. Agric. Food Chem. 2014, 62, 11429−11440

Umami taste is elicited predominantly by the presence of l-glutamate and purine 5’-ribonucleotides, in particular guanosine and inosine 5’-monophosphates. A significant peculiarity of umami compounds is their capacity to interact synergistically.[1] A possible explanation of such phenomenon at a molecular level is that both l-glutamate and ribonucleotides may interact simultaneously with the extracellular “Venus flytrap” (VFT) domain of the umami receptor (a heteromeric complex of two class C G protein-coupled receptors, T1R1 and T1R3), but at different sites.[2] Starting from this model, we reasoned that hybrid compounds, containing the two umami moieties covalently connected through flexible linkers of variable length, could be able to reach both umami receptor sites through a single molecule, thus giving a further insight into the mechanism of synergism. Molecular Dynamics simulations performed on the homology model of the VFT domain suggested that a chain of at least eight carbon atoms is requested to allow the interaction of both glutamate and 5’-ribonucleotide with their respective binding sites. We present here the synthesis of purine 5’-ribonucleotide-glutamate hybrids 3 and 4, characterized by long flexible linkers consisting of eight and ten carbon atoms, respectively, as well as of hybrids 1 and 2, characterized by shorter chains and used as negative controls. Key step in the synthetic route was the activation of the 2-position of the purine ring as a 2-bromo derivative, followed by substitution with the proper diamines. All umami hybrids were tested with the functionally expressed T1R1/T1R3 umami receptor in a cell-based assay.[3] References [1] W. Wang, X. Zhou, Y. Liu, Trends Anal. Chem. 2020, 127, 115876 [2] F. Zhang, B. Klebansky, R. M. Fine, H. Xu, A. Pronin, H. Liu, C. Tachdjian, X. Li, PNAS 2008, 105, 20930-20934 [3] B. Suess, A. Brockhoff, A. Degenhardt, S. Billmayer, W.Meyerhof, T. Hofmann, J. Agric. Food Chem. 2014, 62, 11429−11440

Purine 5’-ribonucleotide-glutamate hybrids as potential tools to investigate the mechanism of umami taste reception / M. Rabuffetti, A. Brockhoff, C. Morelli, S. Sangiorgio, L. Scarabattoli, V.M. Pappalardo, S. Pieraccini, M. Sironi, G. Speranza. ((Intervento presentato al 24. convegno International Roundtable on Nucleosides, Nucleotides and Nucleic Acids (IS3NA-IRT 2022) tenutosi a Stockholm : august 28-31 nel 2022.