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Solano YJ, Kiser PD. Double-duty isomerases: a case study of isomerization-coupled enzymatic catalysis. Trends Biochem Sci 2024:S0968-0004(24)00107-5. [PMID: 38760195 DOI: 10.1016/j.tibs.2024.04.007] [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: 02/15/2024] [Revised: 04/08/2024] [Accepted: 04/23/2024] [Indexed: 05/19/2024]
Abstract
Enzymes can usually be unambiguously assigned to one of seven classes specifying the basic chemistry of their catalyzed reactions. Less frequently, two or more reaction classes are catalyzed by a single enzyme within one active site. Two examples are an isomerohydrolase and an isomero-oxygenase that catalyze isomerization-coupled reactions crucial for production of vision-supporting 11-cis-retinoids. In these enzymes, isomerization is obligately paired and mechanistically intertwined with a second reaction class. A handful of other enzymes carrying out similarly coupled isomerization reactions have been described, some of which have been subjected to detailed structure-function analyses. Herein we review these rarefied enzymes, focusing on the mechanistic and structural basis of their reaction coupling with the goal of revealing catalytic commonalities.
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Affiliation(s)
- Yasmeen J Solano
- Department of Physiology and Biophysics, University of California Irvine School of Medicine, Irvine, CA 92697, USA
| | - Philip D Kiser
- Department of Physiology and Biophysics, University of California Irvine School of Medicine, Irvine, CA 92697, USA; Department of Clinical Pharmacy Practice, University of Irvine School of Pharmacy and Pharmaceutical Sciences, Irvine, CA 92697, USA; Department of Ophthalmology, Gavin Herbert Eye Institute - Center for Translational Vision Research, University of California Irvine School of Medicine, Irvine, CA 92697, USA; Research Service, VA Long Beach Healthcare System, Long Beach, CA 90822, USA.
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Li XB, Wu QY, Wang CZ, Lan JH, Zhang M, Gibson JK, Chai ZF, Shi WQ. Reduction of Np(VI) with hydrazinopropionitrile via water-mediated proton transfer. Phys Chem Chem Phys 2022; 24:17782-17791. [PMID: 35848639 DOI: 10.1039/d2cp01730j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Effectively adjusting and controlling the valence state of neptunium (Np) is essential in its separation during spent fuel reprocessing. Hydrazine and its derivatives as free-salts can selectively reduce Np(VI) to Np(V). Reduction mechanisms of Np(VI) with hydrazine and four derivatives have been explored using multiple theoretical methods in our previous works. Herein, we examine the reduction mechanism of Np(VI) with hydrazinopropionitrile (NCCH2N2H3) which exhibits faster kinetics than most other hydrazine derivatives probably due to its σ-π hyperconjugation effect. Free radical ion pathways I, II and III involving the three types of hydrazine H atoms were found that correspond to the experimentally established mechanism of reduction of two Np(VI) via initial oxidation to [NCCH2N2H3]+˙, followed by conversion to NCCH2N2H (+2H3O+) and ultimately to CH3CN + N2. Potential energy profiles suggest that the second redox stage is rate-determining for all three pathways. Pathway I with water-mediated proton transfer is energetically preferred for hydrazinopropionitrile. Analyses using the approaches of localized molecular orbitals (LMOs), quantum theory of atoms in molecules (QTAIM), and intrinsic reaction coordinate (IRC) elucidate the bonding evolution for the structures on the reaction pathways. The results of the spin density reveal that the reduction of the first Np(VI) ion is the outer-sphere electron transfer, while that of the second Np(VI) ion is the hydrogen transfer. This work offers new insights into the nature of reduction of Np(VI) by hydrazinopropionitrile via water-mediated proton transfer, and provides a basis for designing free-salt reductants for Np separations.
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Affiliation(s)
- Xiao-Bo Li
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China. .,Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, College of Nuclear Science and Technology, Harbin Engineering University, Harbin, Heilongjiang, 150001, China
| | - Qun-Yan Wu
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
| | - Cong-Zhi Wang
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
| | - Jian-Hui Lan
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
| | - Meng Zhang
- Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, College of Nuclear Science and Technology, Harbin Engineering University, Harbin, Heilongjiang, 150001, China
| | - John K Gibson
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
| | - Zhi-Fang Chai
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
| | - Wei-Qun Shi
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
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Valera A, Wang S, Carr R, Trembleau L, Deng H. Characterization of a class II ketol-acid reductoisomerase from Mycobacterium tuberculosis. RSC Adv 2022; 12:10540-10544. [PMID: 35425013 PMCID: PMC8985424 DOI: 10.1039/d1ra08876a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 03/30/2022] [Indexed: 12/31/2022] Open
Abstract
Mycobacterium tuberculosis ketol-acid reductoisomerases have been widely studied due to their metabolic importance towards development of drug-resistant bacteria treatment. We here report the biochemical characterization of a new KARI (MtKARI-II) from a Mycobacterium tuberculosis variant with a similar kinetic profile to class I KARIs. Phylogenetic analysis suggested that MtKARI-II is clustered into a class II KARI superfamily. Biochemical characterization of an unusual class II KARI (MtKARI-II) from a Mycobacterium tuberculosis variant.![]()
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Affiliation(s)
- Ane Valera
- Department of Chemistry, University of Aberdeen Aberdeen AB24 3UE Scotland UK
| | - Shan Wang
- Department of Chemistry, University of Aberdeen Aberdeen AB24 3UE Scotland UK
| | | | - Laurent Trembleau
- Department of Chemistry, University of Aberdeen Aberdeen AB24 3UE Scotland UK
| | - Hai Deng
- Department of Chemistry, University of Aberdeen Aberdeen AB24 3UE Scotland UK
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