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Sowińska A, Rostkowski M, Krzemińska A, Englman T, Gelman F, Dybala-Defratyka A. Insights into generalization of the rate-limiting steps of the dehalogenation by LinB and DhaA: A computational approach. Arch Biochem Biophys 2023:109675. [PMID: 37343813 DOI: 10.1016/j.abb.2023.109675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 06/15/2023] [Accepted: 06/17/2023] [Indexed: 06/23/2023]
Abstract
LinB and DhaA are well-known haloalkane dehalogenases (HLDs) capable of converting a plethora of halogenated alkanes, also those considered persistent pollutants. The dehalogenation reaction that these two enzymes catalyze has been studied to determine its rate-limiting step (rls) for the last two decades now. As a result, it has been determined that HLDs can show different rate-limiting steps for individual substrates, and at this point we do not have a basis for any generalization in this matter. Therefore, in this work we aimed at gaining insights into the enzymatic dehalogenation of selected dibromo- and bromochloro-ethanes and propanes by LinB and DhaA using computational approach to determine whether defined structural similarities of the substrates result in a unified mechanism and the same rls. By predicting halogen binding isotope effects (BIEs) as well as computing interaction energy for each HLD-ligand complex the nature of the protein-ligand interactions has been characterized. Furthermore, C and Br kinetic isotope effects (KIEs) as well as the minimum free energy paths (MFEPs) were computed to investigate the chemical reaction for the selected systems. Accuracy of the approach and robustness of the computational predictions were validated by measuring KIEs on the selected reactions. Overall results strongly indicate that any generalization with respect to the enzymatic process involving various ligands in the case of DhaA is impossible, even if the considered ligands are structurally very similar as those analyzed in the present study. Moreover, even small structural differences such as changing of one of the (non-leaving) halogen substituents may lead to significant changes in the enzymatic process and result in a different rls in the case of LinB. It has also been demonstrated that KIEs themselves cannot be used as rls indicators in the reactions catalyzed by the studied HLDs.
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Affiliation(s)
- Agata Sowińska
- Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924, Lodz, Poland
| | - Michał Rostkowski
- Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924, Lodz, Poland
| | - Agnieszka Krzemińska
- Institute of Physics, Lodz University of Technology, Wolczanska 217/221, 93-005, Lodz, Poland
| | - Tzofia Englman
- The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Faina Gelman
- Geological Survey of Israel, Yeshayahu Leibowitz 32, Jerusalem, 9692100, Israel
| | - Agnieszka Dybala-Defratyka
- Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924, Lodz, Poland.
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Giese TJ, York DM. Estimation of frequency factors for the calculation of kinetic isotope effects from classical and path integral free energy simulations. J Chem Phys 2023; 158:174105. [PMID: 37125722 PMCID: PMC10154067 DOI: 10.1063/5.0147218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 04/17/2023] [Indexed: 05/02/2023] Open
Abstract
We use the modified Bigeleisen-Mayer equation to compute kinetic isotope effect values for non-enzymatic phosphoryl transfer reactions from classical and path integral molecular dynamics umbrella sampling. The modified form of the Bigeleisen-Mayer equation consists of a ratio of imaginary mode vibrational frequencies and a contribution arising from the isotopic substitution's effect on the activation free energy, which can be computed from path integral simulation. In the present study, we describe a practical method for estimating the frequency ratio correction directly from umbrella sampling in a manner that does not require normal mode analysis of many geometry optimized structures. Instead, the method relates the frequency ratio to the change in the mass weighted coordinate representation of the minimum free energy path at the transition state induced by isotopic substitution. The method is applied to the calculation of 16/18O and 32/34S primary kinetic isotope effect values for six non-enzymatic phosphoryl transfer reactions. We demonstrate that the results are consistent with the analysis of geometry optimized transition state ensembles using the traditional Bigeleisen-Mayer equation. The method thus presents a new practical tool to enable facile calculation of kinetic isotope effect values for complex chemical reactions in the condensed phase.
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Affiliation(s)
- Timothy J. Giese
- Laboratory for Biomolecular Simulation Research, Institute for Quantitative Biomedicine and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Darrin M. York
- Laboratory for Biomolecular Simulation Research, Institute for Quantitative Biomedicine and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, USA
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Pokora M, Paneth A, Paneth P. Non-Covalent Isotope Effects. J Phys Chem Lett 2023; 14:3735-3742. [PMID: 37042752 PMCID: PMC10123821 DOI: 10.1021/acs.jpclett.3c00610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Accepted: 04/04/2023] [Indexed: 06/19/2023]
Abstract
In this Perspective, we present examples of isotope effects that originate from noncovalent interactions, mainly hydrogen bonding, electrostatics, and confinement. They are traditionally widely used in isotopic enrichment processes, as well as in studies of mechanisms of different (bio)chemical and physical phenomena. We then show the emerging areas of their applications, mainly medical and material sciences. We stress that these emerging applications require either high enrichment or isotopic substitution, which requires the development of new effective techniques of isotopic purification.
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Affiliation(s)
- Mateusz Pokora
- International
Center of Research on Innovative Biobased Materials (ICRI-BioM) −
International Research Agenda, Lodz University
of Technology, Stefanowskiego 2/22, 90-924 Lodz, Poland
| | - Agata Paneth
- Chair
and Department of Organic Chemistry, Faculty of Pharmacy, Medical University of Lublin, Chodzki 4A, 20-093 Lublin, Poland
| | - Piotr Paneth
- International
Center of Research on Innovative Biobased Materials (ICRI-BioM) −
International Research Agenda, Lodz University
of Technology, Stefanowskiego 2/22, 90-924 Lodz, Poland
- Institute
of Applied Radiation Chemistry, Lodz University
of Technology, Zeromskiego
116, 90-537 Lodz, Poland
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Khan AM, Gharasoo M, Wick LY, Thullner M. Phase-specific stable isotope fractionation effects during combined gas-liquid phase exchange and biodegradation. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 309:119737. [PMID: 35817302 DOI: 10.1016/j.envpol.2022.119737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 06/28/2022] [Accepted: 07/04/2022] [Indexed: 06/15/2023]
Abstract
Stable isotope fractionation of toluene under dynamic phase exchange was studied aiming at ascertaining the effects of gas-liquid partitioning and biodegradation of toluene stable isotope composition in liquid-air phase exchange reactors (Laper). The liquid phase consisted of a mixture of aqueous minimal media, a known amount of a mixture of deuterated (toluene-d) and non-deuterated toluene (toluene-h), and bacteria of toluene degrading strain Pseudomonas putida KT2442. During biodegradation experiments, the liquid and air-phase concentrations of both toluene isotopologues were monitored to determine the observable stable isotope fractionation in each phase. The results show a strong fractionation in both phases with apparent enrichment factors beyond -800‰. An offset was observed between enrichment factors in the liquid and the gas phase with gas-phase values showing a stronger fractionation in the gas than in the liquid phase. Numerical simulation and parameter fitting routine was used to challenge hypotheses to explain the unexpected experimental data. The numerical results showed that either a very strong, yet unlikely, fractionation of the phase exchange process or a - so far unreported - direct consumption of gas phase compounds by aqueous phase microorganisms could explain the observed fractionation effects. The observed effect can be of relevance for the analysis of volatile contaminant biodegradation using stable isotope analysis in unsaturated subsurface compartments or other environmental compartment containing a gas and a liquid phase.
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Affiliation(s)
- Ali M Khan
- Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Mehdi Gharasoo
- Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Lukas Y Wick
- Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Martin Thullner
- Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany.
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