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Cirri D, Bazzicalupi C, Ryde U, Bergmann J, Binacchi F, Nocentini A, Pratesi A, Gratteri P, Messori L. Computationally enhanced X-ray diffraction analysis of a gold(III) complex interacting with the human telomeric DNA G-quadruplex. Unravelling non-unique ligand positioning. Int J Biol Macromol 2022; 211:506-513. [PMID: 35561865 DOI: 10.1016/j.ijbiomac.2022.05.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/14/2022] [Accepted: 05/04/2022] [Indexed: 11/18/2022]
Abstract
The crystal structure of the human telomeric DNA Tel24 G-quadruplex (Tel24 = TAG3(T2AG3)3T) in complex with the novel [AuL] species (with L = 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine - TPymT-α) was solved by a novel joint molecular mechanical (MM)/quantum mechanical (QM) innovative approach. The quantum-refinement crystallographic method (crystallographic refinement enhanced with quantum mechanical calculation) was adapted to treat the [AuL]/G-quadruplex structure, where each gold complex in the binding site was found spread over four equally occupied positions. The four positions were first determined by docking restrained to the crystallographically determined metal ions' coordinates. Then, the quantum refinement method was used to resolve the poorly defined density around the ligands and improve the crystallographic determination, revealing that the binding preferences of this metallodrug toward Tel24 G-quadruplex arise from a combined effect of pyrimidine stacking, metal-guanine interactions and charge-charge neutralizing action of the π-acid triazine. The occurrence of interaction in solution with the Tel24 G-quadruplex DNA was further proved through DNA melting experiments, which showed a slight destabilisation of the quadruplex upon adduct formation.
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Affiliation(s)
- Damiano Cirri
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy
| | - Carla Bazzicalupi
- Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy.
| | - Ulf Ryde
- Division of Theoretical Chemistry, Lund University, Chemical Centre, P. O. Box 124, SE-221 00 Lund, Sweden.
| | - Justin Bergmann
- Division of Theoretical Chemistry, Lund University, Chemical Centre, P. O. Box 124, SE-221 00 Lund, Sweden
| | - Francesca Binacchi
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy
| | - Alessio Nocentini
- Department NEUROFARBA - Pharmaceutical and Nutraceutical Section and Laboratory of Molecular Modeling Cheminformatics & QSAR, University of Florence, Via U. Schiff 6, 50019, Sesto Fiorentino, Florence, Italy
| | - Alessandro Pratesi
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy
| | - Paola Gratteri
- Department NEUROFARBA - Pharmaceutical and Nutraceutical Section and Laboratory of Molecular Modeling Cheminformatics & QSAR, University of Florence, Via U. Schiff 6, 50019, Sesto Fiorentino, Florence, Italy.
| | - Luigi Messori
- Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy
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