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Fernández-Sainz J, Pacheco-Liñán PJ, Ripoll C, González-Fuentes J, Albaladejo J, Bravo I, Garzón-Ruiz A. Unusually High Affinity of the PLK Inhibitors RO3280 and GSK461364 to HSA and Its Possible Pharmacokinetic Implications. Mol Pharm 2023; 20:1631-1642. [PMID: 36812406 PMCID: PMC9997069 DOI: 10.1021/acs.molpharmaceut.2c00849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
The binding processes of two Polo-like kinase inhibitors, RO3280 and GSK461364, to the human serum albumin (HSA) protein as well as the protonation equilibria of both compounds have been studied combining absorbance and fluorescence spectroscopy experiments together with density functional theory calculations. We found that the charge states of RO3280 and GSK461364 are +2 and +1, respectively, at the physiological pH. Nevertheless, RO3280 binds to HSA in the charge state +1 prior to a deprotonation pre-equilibrium. Binding constants to site I of HSA of 2.23 × 106 and 8.80 × 104 M-1 were determined for RO3280 and GSK461364, respectively, at 310 K. The binding processes of RO3280 and GSK461364 to HSA are entropy- and enthalpy-driven, respectively. The positive enthalpy found for the RO3280-HSA complex formation could be related to a proton pre-equilibrium of RO3280.
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Affiliation(s)
- Jesús Fernández-Sainz
- Departamento de Química Física, Facultad de Farmacia, Universidad de Castilla-La Mancha, Av. Dr. José María Sánchez Ibáñez, s/n, 02071 Albacete, Spain
| | - Pedro J Pacheco-Liñán
- Departamento de Química Física, Facultad de Farmacia, Universidad de Castilla-La Mancha, Av. Dr. José María Sánchez Ibáñez, s/n, 02071 Albacete, Spain
| | - Consuelo Ripoll
- Departamento de Química Física, Facultad de Farmacia, Universidad de Castilla-La Mancha, Av. Dr. José María Sánchez Ibáñez, s/n, 02071 Albacete, Spain
| | - Joaquín González-Fuentes
- Centro Regional de Investigaciones Biomédicas (CRIB), Unidad Asociada de Biomedicina (UCLM-CSIC), C/ Almansa, 14, 02008 Albacete, Spain
| | - José Albaladejo
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Avenida Camilo José Cela, 10, 13071 Ciudad Real, Spain
| | - Iván Bravo
- Departamento de Química Física, Facultad de Farmacia, Universidad de Castilla-La Mancha, Av. Dr. José María Sánchez Ibáñez, s/n, 02071 Albacete, Spain.,Centro Regional de Investigaciones Biomédicas (CRIB), Unidad Asociada de Biomedicina (UCLM-CSIC), C/ Almansa, 14, 02008 Albacete, Spain
| | - Andrés Garzón-Ruiz
- Departamento de Química Física, Facultad de Farmacia, Universidad de Castilla-La Mancha, Av. Dr. José María Sánchez Ibáñez, s/n, 02071 Albacete, Spain
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Allen JP, Chamberlain KD, Williams JC. Identification of amino acid residues in a proton release pathway near the bacteriochlorophyll dimer in reaction centers from Rhodobacter sphaeroides. PHOTOSYNTHESIS RESEARCH 2023; 155:23-34. [PMID: 36197600 DOI: 10.1007/s11120-022-00968-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 09/21/2022] [Indexed: 06/16/2023]
Abstract
Insight into control of proton transfer, a crucial attribute of cellular functions, can be gained from investigations of bacterial reaction centers. While the uptake of protons associated with the reduction of the quinone is well characterized, the release of protons associated with the oxidized bacteriochlorophyll dimer has been poorly understood. Optical spectroscopy and proton release/uptake measurements were used to examine the proton release characteristics of twelve mutant reaction centers, each containing a change in an amino acid residue near the bacteriochlorophyll dimer. The mutant reaction centers had optical spectra similar to wild-type and were capable of transferring electrons to the quinones after light excitation of the bacteriochlorophyll dimer. They exhibited a large range in the extent of proton release and in the slow recovery of the optical signal for the oxidized dimer upon continuous illumination. Key roles were indicated for six amino acid residues, Thr L130, Asp L155, Ser L244, Arg M164, Ser M190, and His M193. Analysis of the results points to a hydrogen-bond network that contains these residues, with several additional residues and bound water molecules, forming a proton transfer pathway. In addition to proton transfer, the properties of the pathway are proposed to be responsible for the very slow charge recombination kinetics observed after continuous illumination. The characteristics of this pathway are compared to proton transfer pathways near the secondary quinone as well as those found in photosystem II and cytochrome c oxidase.
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Affiliation(s)
- J P Allen
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287-1604, USA.
| | - K D Chamberlain
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287-1604, USA
| | - J C Williams
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287-1604, USA
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d'Auriac JCA, Iglói F. Statistics of percolating clusters in a model of photosynthetic bacteria. Phys Rev E 2021; 103:052103. [PMID: 34134283 DOI: 10.1103/physreve.103.052103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 04/15/2021] [Indexed: 06/12/2023]
Abstract
In photosynthetic organisms the energy of the illuminating light is absorbed by the antenna complexes and transmitted by the excitons to the reaction centers (RCs). The energy of light is either absorbed by the RCs, leading to their "closing" or is emitted through fluorescence. The dynamics of the light absorption is described by a simple model developed for exciton migration that involves the exciton hopping probability and the exciton lifetime. During continuous illumination the fraction of closed RCs x continuously increases, and at a critical threshold x_{c}, a percolation transition takes place. Performing extensive Monte Carlo simulations, we study the properties of the transition in this correlated percolation model. We measure the spanning probability in the vicinity of x_{c}, as well as the fractal properties of the critical percolating cluster, both in the bulk and at the surface.
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Affiliation(s)
| | - Ferenc Iglói
- Wigner Research Centre for Physics, Institute for Solid State Physics and Optics, P.O. Box 49, H-1525 Budapest, Hungary
- Institute of Theoretical Physics, Szeged University, H-6720 Szeged, Hungary
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Maróti P, Kovács IA, Kis M, Smart JL, Iglói F. Correlated clusters of closed reaction centers during induction of intact cells of photosynthetic bacteria. Sci Rep 2020; 10:14012. [PMID: 32814810 PMCID: PMC7438532 DOI: 10.1038/s41598-020-70966-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 07/29/2020] [Indexed: 01/18/2023] Open
Abstract
Antenna systems serve to absorb light and to transmit excitation energy to the reaction center (RC) in photosynthetic organisms. As the emitted (bacterio)chlorophyll fluorescence competes with the photochemical utilization of the excitation, the measured fluorescence yield is informed by the migration of the excitation in the antenna. In this work, the fluorescence yield concomitant with the oxidized dimer (P+) of the RC were measured during light excitation (induction) and relaxation (in the dark) for whole cells of photosynthetic bacterium Rhodobacter sphaeroides lacking cytochrome c2 as natural electron donor to P+ (mutant cycA). The relationship between the fluorescence yield and P+ (fraction of closed RC) showed deviations from the standard Joliot-Lavergne-Trissl model: (1) the hyperbola is not symmetric and (2) exhibits hysteresis. These phenomena originate from the difference between the delays of fluorescence relative to P+ kinetics during induction and relaxation, and in structural terms from the non-random distribution of the closed RCs during induction. The experimental findings are supported by Monte Carlo simulations and by results from statistical physics based on random walk approximations of the excitation in the antenna. The applied mathematical treatment demonstrates the generalization of the standard theory and sets the stage for a more adequate description of the long-debated kinetics of fluorescence and of the delicate control and balance between efficient light harvest and photoprotection in photosynthetic organisms.
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Affiliation(s)
- Péter Maróti
- Department of Medical Physics and Informatics, Szeged University, Rerrich Béla tér 1., 6720, Szeged, Hungary.
| | - István A Kovács
- Department of Physics and Astronomy, Northwestern University, Evanston, IL, 60208-3112, USA
- Wigner Research Centre for Physics, Institute for Solid State Physics and Optics, P.O. Box 49, 1525, Budapest, Hungary
- Department of Network and Data Science, Central European University, Budapest, 1051, Hungary
| | - Mariann Kis
- Department of Medical Physics and Informatics, Szeged University, Rerrich Béla tér 1., 6720, Szeged, Hungary
| | - James L Smart
- Department of Biological Sciences, University of Tennessee at Martin, Martin, TN, 38238, USA
| | - Ferenc Iglói
- Wigner Research Centre for Physics, Institute for Solid State Physics and Optics, P.O. Box 49, 1525, Budapest, Hungary
- Institute of Theoretical Physics, Szeged University, 6720, Szeged, Hungary
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