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Koenekoop L, Åqvist J. Computational Analysis of Heat Capacity Effects in Protein-Ligand Binding. J Chem Theory Comput 2024; 20:5708-5716. [PMID: 38870420 PMCID: PMC11238534 DOI: 10.1021/acs.jctc.4c00525] [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: 06/15/2024]
Abstract
Heat capacity effects in protein-ligand binding as measured by calorimetric experiments have recently attracted considerable attention, particularly in the field of enzyme inhibitor design. A significant negative heat capacity change upon ligand binding implies a marked temperature dependence of the binding enthalpy, which is of high relevance for attempts to optimize protein-ligand interactions. In this work, we address the question of how well such heat capacity changes can be predicted by computer simulations. We examine a series of human thrombin inhibitors that all bind with ΔCp values of about -0.4 kcal/mol/K and calculate heat capacity changes from plain molecular dynamics simulations of the bound and free states of the enzyme and ligand. The results show that accurate ΔCp estimates within a few tenths of a kcal/mol/K of the experimental values can be obtained with this approach. This allows us to address the structural and energetic origin of the negative heat capacity changes for the thrombin inhibitors, and it is found that conformational equilibria of the free ligands in solution make a major contribution to the observed effect.
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Affiliation(s)
- Lucien Koenekoop
- Department of Cell & Molecular Biology, Uppsala University, Biomedical Center, SE-751 24 Uppsala, Sweden
| | - Johan Åqvist
- Department of Cell & Molecular Biology, Uppsala University, Biomedical Center, SE-751 24 Uppsala, Sweden
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2
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Oanca G, Åqvist J. Why Do Empirical Valence Bond Simulations Yield Accurate Arrhenius Plots? J Chem Theory Comput 2024; 20:2582-2591. [PMID: 38452751 DOI: 10.1021/acs.jctc.4c00126] [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: 03/09/2024]
Abstract
Computer simulations of the temperature dependence of enzyme reactions using the empirical valence bond (EVB) method have proven to give very accurate results in terms of the thermodynamic activation parameters. Here, we analyze the reasons for why such simulations are able to correctly capture activation enthalpies and entropies and how sensitive these quantities are to parametrization of the reactive potential energy function. We examine first the solution reference reaction for the enzyme ketosteroid isomerase, which corresponds to the acetate catalyzed deprotonation of the steroid in water. The experimentally determined activation parameters for this reaction turn out to be remarkably well reproduced by the calculations. By modifying the EVB potential so that the activation and reaction free energies become significantly shifted, we show that the activation entropy is basically invariant to such changes and that ΔS⧧ is instead determined by the specific mixture of the underlying force fields in the transition state region. The coefficients of this mixture do not change appreciably when the EVB potential is modified within reasonable limits, and hence, the estimate of ΔS⧧ becomes very robust. This is further verified by examining a more complex concerted hydride and proton transfer reaction in the enzyme hydroxybutyrate dehydrogenase.
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Affiliation(s)
- Gabriel Oanca
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, SE-751 24 Uppsala, Sweden
| | - Johan Åqvist
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, SE-751 24 Uppsala, Sweden
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Nowak JS, Otzen DE. Helping proteins come in from the cold: 5 burning questions about cold-active enzymes. BBA ADVANCES 2023; 5:100104. [PMID: 38162634 PMCID: PMC10755280 DOI: 10.1016/j.bbadva.2023.100104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 08/21/2023] [Accepted: 09/05/2023] [Indexed: 01/03/2024] Open
Abstract
Enzymes from psychrophilic (cold-loving) organisms have attracted considerable interest over the past decades for their potential in various low-temperature industrial processes. However, we still lack large-scale commercialization of their activities. Here, we review their properties, limitations and potential. Our review is structured around answers to 5 central questions: 1. How do cold-active enzymes achieve high catalytic rates at low temperatures? 2. How is protein flexibility connected to cold-activity? 3. What are the sequence-based and structural determinants for cold-activity? 4. How does the thermodynamic stability of psychrophilic enzymes reflect their cold-active capabilities? 5. How do we effectively identify novel cold-active enzymes, and can we apply them in an industrial context? We conclude that emerging screening technologies combined with big-data handling and analysis make it reasonable to expect a bright future for our understanding and exploitation of cold-active enzymes.
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Affiliation(s)
- Jan Stanislaw Nowak
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, DK – 8000 Aarhus C, Denmark
| | - Daniel E. Otzen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, DK – 8000 Aarhus C, Denmark
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Oanca G, van der Ent F, Åqvist J. Efficient Empirical Valence Bond Simulations with GROMACS. J Chem Theory Comput 2023; 19:6037-6045. [PMID: 37623818 PMCID: PMC10500987 DOI: 10.1021/acs.jctc.3c00714] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Indexed: 08/26/2023]
Abstract
We describe a protocol to perform empirical valence bond (EVB) simulations using GROMACS software. EVB is a fast and reliable method that allows one to determine the reaction free-energy profiles in complex systems, such as enzymes, by employing classical force fields to represent a chemical reaction. Therefore, running EVB simulations is basically as fast as any classical molecular dynamics simulation, and the method uses standard free-energy calculations to map the free-energy change along a given reaction path. To exemplify and validate our EVB implementation, we replicated two cases of our earlier enzyme simulations. One of these addresses the decomposition of the activation free energy into its enthalpic and entropic components, and the other is focused on calculating the overall catalytic effect of the enzyme compared to the same reaction in water. These two examples give virtually identical results to those obtained with programs that were specifically designed for EVB simulations and show that the GROMACS implementation is robust and can be used for very large systems.
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Affiliation(s)
- Gabriel Oanca
- Department of Cell and Molecular Biology,
Biomedical Center, Uppsala University, Uppsala SE-751 24, Sweden
| | - Florian van der Ent
- Department of Cell and Molecular Biology,
Biomedical Center, Uppsala University, Uppsala SE-751 24, Sweden
| | - Johan Åqvist
- Department of Cell and Molecular Biology,
Biomedical Center, Uppsala University, Uppsala SE-751 24, Sweden
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van der Ent F, Skagseth S, Lund BA, Sǒan J, Griese JJ, Brandsdal BO, Åqvist J. Computational design of the temperature optimum of an enzyme reaction. SCIENCE ADVANCES 2023; 9:eadi0963. [PMID: 37379391 DOI: 10.1126/sciadv.adi0963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 05/23/2023] [Indexed: 06/30/2023]
Abstract
Cold-adapted enzymes are characterized both by a higher catalytic activity at low temperatures and by having their temperature optimum down-shifted, compared to mesophilic orthologs. In several cases, the optimum does not coincide with the onset of protein melting but reflects some other type of inactivation. In the psychrophilic α-amylase from an Antarctic bacterium, the inactivation is thought to originate from a specific enzyme-substrate interaction that breaks around room temperature. Here, we report a computational redesign of this enzyme aimed at shifting its temperature optimum upward. A set of mutations designed to stabilize the enzyme-substrate interaction were predicted by computer simulations of the catalytic reaction at different temperatures. The predictions were verified by kinetic experiments and crystal structures of the redesigned α-amylase, showing that the temperature optimum is indeed markedly shifted upward and that the critical surface loop controlling the temperature dependence approaches the target conformation observed in a mesophilic ortholog.
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Affiliation(s)
- Florian van der Ent
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Box 596, SE-751 24 Uppsala, Sweden
| | - Susann Skagseth
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Tromsø-The Arctic University of Norway, N9037 Tromsø, Norway
| | - Bjarte A Lund
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Box 596, SE-751 24 Uppsala, Sweden
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Tromsø-The Arctic University of Norway, N9037 Tromsø, Norway
| | - Jaka Sǒan
- National Institute of Chemistry, SI-1001 Ljubljana, Slovenia
| | - Julia J Griese
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Box 596, SE-751 24 Uppsala, Sweden
| | - Bjørn O Brandsdal
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Tromsø-The Arctic University of Norway, N9037 Tromsø, Norway
| | - Johan Åqvist
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Box 596, SE-751 24 Uppsala, Sweden
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Tromsø-The Arctic University of Norway, N9037 Tromsø, Norway
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