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Frere GA, Hasabnis A, Francisco CB, Suleiman M, Alimowska O, Rahmatullah R, Gould J, Su CYC, Voznyy O, Gunning PT, Basso EA, Prosser RS. Next-Generation Tags for Fluorine Nuclear Magnetic Resonance: Designing Amplification of Chemical Shift Sensitivity. J Am Chem Soc 2024; 146:3052-3064. [PMID: 38279916 DOI: 10.1021/jacs.3c09730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2024]
Abstract
Fluorine NMR is a highly sensitive technique for delineating the conformational states of biomolecules and has shown great utility in drug screening and in understanding protein function. Current fluorinated protein tags leverage the intrinsic chemical shift sensitivity of the 19F nucleus to detect subtle changes in protein conformation and topology. This chemical shift sensitivity can be amplified by embedding the fluorine or trifluoromethyl reporter within a pyridone. Due to their polarizability and rapid tautomerization, pyridones exhibit a greater range of electron delocalization and correspondingly greater 19F NMR chemical shift dispersion. To assess the chemical shift sensitivity of these tautomeric probes to the local environment, 19F NMR spectra of all possible monofluorinated and trifluoromethyl-tagged versions of 2-pyridone were recorded in methanol/water mixtures ranging from 100% methanol to 100% water. 4-Fluoro-2-pyridone and 6-(trifluoromethyl)-2-pyridone (6-TFP) displayed the greatest sensitivity of the monofluorinated and trifluoromethylated pyridones, exceeding that of known conventional CF3 reporters. To evaluate the utility of tautomeric pyridone tags for 19F NMR of biomolecules, the alpha subunit of the stimulatory G protein (Gsα) and human serum albumin (HSA) were each labeled with a thiol-reactive derivative of 6-TFP and the spectra were recorded as a function of various adjuvants and drugs. The tautomeric tag outperformed the conventional tag, 2-bromo-N-(4-(trifluoromethyl)phenyl)acetamide through the improved resolution of several functional states.
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Affiliation(s)
- Geordon A Frere
- Department of Chemistry, University of Toronto, CPS, UTM, 3359 Mississauga Rd, Mississauga, ON L5L 1C6, Canada
| | - Advait Hasabnis
- Department of Chemistry, University of Toronto, CPS, UTM, 3359 Mississauga Rd, Mississauga, ON L5L 1C6, Canada
| | - Camila B Francisco
- Department of Chemistry, University of Toronto, CPS, UTM, 3359 Mississauga Rd, Mississauga, ON L5L 1C6, Canada
- Department of Chemistry, State University of Maringá, 5790, Maringá 87020-900, Brazil
| | - Motasem Suleiman
- Department of Chemistry, University of Toronto, CPS, UTM, 3359 Mississauga Rd, Mississauga, ON L5L 1C6, Canada
| | - Olga Alimowska
- Department of Chemistry, University of Toronto, CPS, UTM, 3359 Mississauga Rd, Mississauga, ON L5L 1C6, Canada
| | - Rima Rahmatullah
- Department of Chemistry, University of Toronto, CPS, UTM, 3359 Mississauga Rd, Mississauga, ON L5L 1C6, Canada
| | - Jerome Gould
- Department of Chemistry, University of Toronto, CPS, UTM, 3359 Mississauga Rd, Mississauga, ON L5L 1C6, Canada
| | - Celia Yi-Chia Su
- Department of Chemistry, University of Toronto, CPS, UTM, 3359 Mississauga Rd, Mississauga, ON L5L 1C6, Canada
| | - Oleksandr Voznyy
- Department of Chemistry, University of Toronto, CPS, UTM, 3359 Mississauga Rd, Mississauga, ON L5L 1C6, Canada
| | - Patrick T Gunning
- Department of Chemistry, University of Toronto, CPS, UTM, 3359 Mississauga Rd, Mississauga, ON L5L 1C6, Canada
| | - Ernani A Basso
- Department of Chemistry, State University of Maringá, 5790, Maringá 87020-900, Brazil
| | - Robert S Prosser
- Department of Chemistry, University of Toronto, CPS, UTM, 3359 Mississauga Rd, Mississauga, ON L5L 1C6, Canada
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Hansen PE. The Synergy between Nuclear Magnetic Resonance and Density Functional Theory Calculations. Molecules 2024; 29:336. [PMID: 38257249 PMCID: PMC10821511 DOI: 10.3390/molecules29020336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2023] [Revised: 01/05/2024] [Accepted: 01/08/2024] [Indexed: 01/24/2024] Open
Abstract
This paper deals with the synergy between Nuclear Magnetic Resonance (NMR) spectroscopic investigations and DFT calculations, mainly of NMR parameters. Both the liquid and the solid states are discussed here. This text is a mix of published results supplemented with new findings. This paper deals with examples in which useful results could not have been obtained without combining NMR measurements and DFT calculations. Examples of such cases are tautomeric systems in which NMR data are calculated for the tautomers; hydrogen-bonded systems in which better XH bond lengths can be determined; cage compounds for which assignment cannot be made based on NMR data alone; revison of already published structures; ionic compounds for which reference data are not available; assignment of solid-state spectra and crystal forms; and the creation of libraries for biological molecules. In addition to these literature cases, a revision of a cage structure and substituent effects on pyrroles is also discussed.
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Affiliation(s)
- Poul Erik Hansen
- Department of Science and Environment, Roskilde University, DK-4000 Roskilde, Denmark
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Baranac-Stojanović M, Aleksić J, Stojanović M. Theoretical investigation of tautomerism of 2- and 4-pyridones: origin, substituent and solvent effects. Org Biomol Chem 2023; 22:144-158. [PMID: 38051113 DOI: 10.1039/d3ob01588b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Computational investigation at the BHandHLYP/6-311+G(d,p) level of theory of the gas-phase tautomerism of 2- and 4-pyridones confirmed the slight prevalence of lactim in the case of the former, but its dominance in the case of the latter, as shown previously. Examination of aromaticity by using HOMA, EDDB, NBOdel, NICS and AICD led to the conclusion that tautomerization of 4-pyridone results in greater aromaticity gain. It is also driven by the Pauli repulsion relief, which was revealed by the tautomerization energy decomposition analysis. By contrast, in the case of 2-pyridone, lactim is favoured by orbital and electrostatic interactions and disfavoured by the Pauli repulsion. Aromaticity gain in this case is smaller. The position of the tautomeric equilibrium can be modulated by substituent inductive effects (Cl and F), inductive and resonance effects (NH2 and NO2), hydrogen bonding (NO2), and medium polarity, the increase of which increases lactam population.
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Affiliation(s)
- Marija Baranac-Stojanović
- University of Belgrade - Faculty of Chemistry, Studentski trg 12-16, P. O. Box 158, 11000 Belgrade, Serbia.
| | - Jovana Aleksić
- University of Belgrade - Institute of Chemistry, Technology and Metallurgy - Center for Chemistry, Njegoševa 12, P. O. Box 473, 11000 Belgrade, Serbia
| | - Milovan Stojanović
- University of Belgrade - Institute of Chemistry, Technology and Metallurgy - Center for Chemistry, Njegoševa 12, P. O. Box 473, 11000 Belgrade, Serbia
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