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Wang Z, Yu Q, Zhao Z, Zhang Y. Ferroheme/Ferriheme Directly Involved in the Synthesis and Decomposition of Hydrazine as an Electron Carrier during Anammox. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:10140-10148. [PMID: 38781353 DOI: 10.1021/acs.est.3c08525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
Anammox bacteria performed the reaction of NH4+ and NO with hydrazine synthase to produce N2H4, followed by the decomposition of N2H4 with hydrazine dehydrogenase to generate N2. Ferroheme/ferriheme, which serves as the active center of both hydrazine synthase and hydrazine dehydrogenase, is thought to play a crucial role in the synthesis and decomposition of N2H4 during Anammox due to its high redox activity. However, this has yet to be proven and the exact mechanisms by which ferroheme/ferriheme is involved in the Anammox process remain unclear. In this study, abiotic and biological assays confirmed that ferroheme participated in NH4+ and NO reactions to generate N2H4 and ferriheme, and the produced N2H4 reacted with ferriheme to generate N2 and ferroheme. In other words, the ferroheme/ferriheme cycle drove the continuous reaction between NH4+ and NO. Raman, ultraviolet-visible spectroscopy, and X-ray absorption fine structure spectroscopy confirmed that ferroheme/ferriheme is involved in the synthesis and decomposition of N2H4 via the core FeII/FeIII cycle. The mechanism of ferroheme/ferriheme participation in the synthesis and decomposition of N2H4 was proposed by density functional theory calculations. These findings revealed for the first time the heme electron transfer mechanisms, which are of great significance for deepening the understanding of Anammox.
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Affiliation(s)
- Zhenxin Wang
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian116024, China
| | - Qilin Yu
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian116024, China
| | - Zhiqiang Zhao
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian116024, China
| | - Yaobin Zhang
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian116024, China
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Wang X, Liu M, Yu C, Li J, Zhou X. Biofilm formation: mechanistic insights and therapeutic targets. MOLECULAR BIOMEDICINE 2023; 4:49. [PMID: 38097907 PMCID: PMC10721784 DOI: 10.1186/s43556-023-00164-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 12/06/2023] [Indexed: 12/18/2023] Open
Abstract
Biofilms are complex multicellular communities formed by bacteria, and their extracellular polymeric substances are observed as surface-attached or non-surface-attached aggregates. Many types of bacterial species found in living hosts or environments can form biofilms. These include pathogenic bacteria such as Pseudomonas, which can act as persistent infectious hosts and are responsible for a wide range of chronic diseases as well as the emergence of antibiotic resistance, thereby making them difficult to eliminate. Pseudomonas aeruginosa has emerged as a model organism for studying biofilm formation. In addition, other Pseudomonas utilize biofilm formation in plant colonization and environmental persistence. Biofilms are effective in aiding bacterial colonization, enhancing bacterial resistance to antimicrobial substances and host immune responses, and facilitating cell‒cell signalling exchanges between community bacteria. The lack of antibiotics targeting biofilms in the drug discovery process indicates the need to design new biofilm inhibitors as antimicrobial drugs using various strategies and targeting different stages of biofilm formation. Growing strategies that have been developed to combat biofilm formation include targeting bacterial enzymes, as well as those involved in the quorum sensing and adhesion pathways. In this review, with Pseudomonas as the primary subject of study, we review and discuss the mechanisms of bacterial biofilm formation and current therapeutic approaches, emphasizing the clinical issues associated with biofilm infections and focusing on current and emerging antibiotic biofilm strategies.
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Affiliation(s)
- Xinyu Wang
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Ming Liu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Chuanjiang Yu
- Institute for Cancer Genetics, Columbia University, New York, NY, 10032, USA
| | - Jing Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, Sichuan, China.
| | - Xikun Zhou
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China.
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Sarkar A, Bhakta S, Chattopadhyay S, Dey A. Role of distal arginine residue in the mechanism of heme nitrite reductases. Chem Sci 2023; 14:7875-7886. [PMID: 37502318 PMCID: PMC10370594 DOI: 10.1039/d3sc01777j] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 06/14/2023] [Indexed: 07/29/2023] Open
Abstract
Heme nitrite reductases reduce NO2- by 1e-/2H+ to NO or by 6e-/8H+ to NH4+ which are key steps in the global nitrogen cycle. Second-sphere residues, such as arginine (with a guanidine head group), are proposed to play a key role in the reaction by assisting substrate binding and hydrogen bonding and by providing protons to the active site for the reaction. The reactivity of an iron porphyrin with a NO2- covalently attached to a guanidinium arm in its 2nd sphere was investigated to understand the role of arginine residues in the 2nd sphere of heme nitrite reductases. The presence of the guanidinium residue allows the synthetic ferrous porphyrin to reduce NO2- and produce a ferrous nitrosyl species ({FeNO}7), where the required protons are provided by the guanidinium group in the 2nd sphere. However, in the presence of additional proton sources in solution, the reaction of ferrous porphyrin with NO2- results in the formation of ferric porphyrin and the release of NO. Spectroscopic and kinetic data indicated that re-protonation of the guanidine group in the 2nd sphere by an external proton source causes NO to dissociate from a ferric nitrosyl species ({FeNO}6) at rates similar to those observed for enzymatic sites. This re-protonation of the guanidine group mimics the proton recharge mechanism in the active site of NiR. DFT calculations indicated that the lability of the Fe-NO bond in the {FeNO}6 species is derived from the greater binding affinity of anions (e.g. NO2-) to the ferric center relative to neutral NO due to hydrogen bonding and electrostatic interaction of these bound anions with the protonated guanidium group in the 2nd sphere. The reduced {FeNO}7 species, once formed, is not affected significantly by the re-protonation of the guanidine residue. These results provide direct insight into the role of the 2nd sphere arginine residue present in the active sites of heme-based NiRs in determining the fate of NO2- reduction. Specifically, the findings using the synthetic model suggest that rapid re-protonation of these arginine residues may trigger the dissociation of NO from the {FeNO}6, which may also be the case in the protein active site.
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Affiliation(s)
- Ankita Sarkar
- School of Chemical Sciences, Indian Association for the Cultivation of Science 2A & 2B Raja S.C. Mullick Road Kolkata WB 700032 India
| | - Snehadri Bhakta
- School of Chemical Sciences, Indian Association for the Cultivation of Science 2A & 2B Raja S.C. Mullick Road Kolkata WB 700032 India
| | - Samir Chattopadhyay
- School of Chemical Sciences, Indian Association for the Cultivation of Science 2A & 2B Raja S.C. Mullick Road Kolkata WB 700032 India
| | - Abhishek Dey
- School of Chemical Sciences, Indian Association for the Cultivation of Science 2A & 2B Raja S.C. Mullick Road Kolkata WB 700032 India
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Lehnert N, Kim E, Dong HT, Harland JB, Hunt AP, Manickas EC, Oakley KM, Pham J, Reed GC, Alfaro VS. The Biologically Relevant Coordination Chemistry of Iron and Nitric Oxide: Electronic Structure and Reactivity. Chem Rev 2021; 121:14682-14905. [PMID: 34902255 DOI: 10.1021/acs.chemrev.1c00253] [Citation(s) in RCA: 90] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Nitric oxide (NO) is an important signaling molecule that is involved in a wide range of physiological and pathological events in biology. Metal coordination chemistry, especially with iron, is at the heart of many biological transformations involving NO. A series of heme proteins, nitric oxide synthases (NOS), soluble guanylate cyclase (sGC), and nitrophorins, are responsible for the biosynthesis, sensing, and transport of NO. Alternatively, NO can be generated from nitrite by heme- and copper-containing nitrite reductases (NIRs). The NO-bearing small molecules such as nitrosothiols and dinitrosyl iron complexes (DNICs) can serve as an alternative vehicle for NO storage and transport. Once NO is formed, the rich reaction chemistry of NO leads to a wide variety of biological activities including reduction of NO by heme or non-heme iron-containing NO reductases and protein post-translational modifications by DNICs. Much of our understanding of the reactivity of metal sites in biology with NO and the mechanisms of these transformations has come from the elucidation of the geometric and electronic structures and chemical reactivity of synthetic model systems, in synergy with biochemical and biophysical studies on the relevant proteins themselves. This review focuses on recent advancements from studies on proteins and model complexes that not only have improved our understanding of the biological roles of NO but also have provided foundations for biomedical research and for bio-inspired catalyst design in energy science.
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Affiliation(s)
- Nicolai Lehnert
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Eunsuk Kim
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Hai T Dong
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Jill B Harland
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Andrew P Hunt
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Elizabeth C Manickas
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Kady M Oakley
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - John Pham
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Garrett C Reed
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Victor Sosa Alfaro
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
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Liu W, Fan Y, He P, Chen H. Complete genome sequence of a nitrate reducing bacteria, Algoriphagus sp. Y33 isolated from the water of the Indian Ocean. Mar Genomics 2021; 59:100861. [PMID: 34493387 DOI: 10.1016/j.margen.2021.100861] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 02/22/2021] [Accepted: 02/22/2021] [Indexed: 10/22/2022]
Abstract
Algoriphagus sp. Y33, is a nitrate-reducing bacterium isolated from the water of Indian Ocean. Here, we present the complete genome sequence of strain Y33. The genome has one circular chromosome of 6,378,979 bp, with an average GC content of 41.86%, and 5757 coding sequences. According to the annotation analysis, strain Y33 encodes 32 proteins related to nitrogen metabolism. To our knowledge, this is the first report of Algoriphagus sp. isolated from the Indian Ocean with the capacity of nitrate reduction, which will provide insights into regulatory mechanisms of nitrate uptake by heterotrophic bacteria and the global nitrogen cycling.
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Affiliation(s)
- Wenfeng Liu
- Key Laboratory of Science and Technology for Marine Ecology and Environment, First Institute of Oceanography, Ministry of Natural Resources, 6 Xianxialing Road, Qingdao 266061, China; Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), China
| | - Yaqin Fan
- Shandong Provincial Key Laboratory of Applied Mycology, College of Life Sciences, Qingdao Agricultural University, Qingdao 266109, China
| | - Peiqing He
- Key Laboratory of Science and Technology for Marine Ecology and Environment, First Institute of Oceanography, Ministry of Natural Resources, 6 Xianxialing Road, Qingdao 266061, China; Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), China.
| | - Hao Chen
- Key Laboratory of Science and Technology for Marine Ecology and Environment, First Institute of Oceanography, Ministry of Natural Resources, 6 Xianxialing Road, Qingdao 266061, China; Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), China.
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6
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Ferousi C, Schmitz RA, Maalcke WJ, Lindhoud S, Versantvoort W, Jetten MSM, Reimann J, Kartal B. Characterization of a nitrite-reducing octaheme hydroxylamine oxidoreductase that lacks the tyrosine cross-link. J Biol Chem 2021; 296:100476. [PMID: 33652023 PMCID: PMC8042395 DOI: 10.1016/j.jbc.2021.100476] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/18/2021] [Accepted: 02/24/2021] [Indexed: 02/06/2023] Open
Abstract
The hydroxylamine oxidoreductase (HAO) family consists of octaheme proteins that harbor seven bis-His ligated electron-transferring hemes and one 5-coordinate catalytic heme with His axial ligation. Oxidative HAOs have a homotrimeric configuration with the monomers covalently attached to each other via a unique double cross-link between a Tyr residue and the catalytic heme moiety of an adjacent subunit. This cross-linked active site heme, termed the P460 cofactor, has been hypothesized to modulate enzyme reactivity toward oxidative catalysis. Conversely, the absence of this cross-link is predicted to favor reductive catalysis. However, this prediction has not been directly tested. In this study, an HAO homolog that lacks the heme-Tyr cross-link (HAOr) was purified to homogeneity from the nitrite-dependent anaerobic ammonium-oxidizing (anammox) bacterium Kuenenia stuttgartiensis, and its catalytic and spectroscopic properties were assessed. We show that HAOr reduced nitrite to nitric oxide and also reduced nitric oxide and hydroxylamine as nonphysiological substrates. In contrast, HAOr was not able to oxidize hydroxylamine or hydrazine supporting the notion that cross-link-deficient HAO enzymes are reductases. Compared with oxidative HAOs, we found that HAOr harbors an active site heme with a higher (at least 80 mV) midpoint potential and a much lower degree of porphyrin ruffling. Based on the physiology of anammox bacteria and our results, we propose that HAOr reduces nitrite to nitric oxide in vivo, providing anammox bacteria with NO, which they use to activate ammonium in the absence of oxygen.
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Affiliation(s)
- Christina Ferousi
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Rob A Schmitz
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Wouter J Maalcke
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Simon Lindhoud
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Wouter Versantvoort
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Mike S M Jetten
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Joachim Reimann
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Boran Kartal
- Microbial Physiology Group, Max Planck Institute for Marine Microbiology, Bremen, Germany.
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Amanullah S, Saha P, Nayek A, Ahmed ME, Dey A. Biochemical and artificial pathways for the reduction of carbon dioxide, nitrite and the competing proton reduction: effect of 2nd sphere interactions in catalysis. Chem Soc Rev 2021; 50:3755-3823. [DOI: 10.1039/d0cs01405b] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Reduction of oxides and oxoanions of carbon and nitrogen are of great contemporary importance as they are crucial for a sustainable environment.
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Affiliation(s)
- Sk Amanullah
- School of Chemical Sciences
- Indian Association for the Cultivation of Science
- Kolkata
- India
| | - Paramita Saha
- School of Chemical Sciences
- Indian Association for the Cultivation of Science
- Kolkata
- India
| | - Abhijit Nayek
- School of Chemical Sciences
- Indian Association for the Cultivation of Science
- Kolkata
- India
| | - Md Estak Ahmed
- School of Chemical Sciences
- Indian Association for the Cultivation of Science
- Kolkata
- India
| | - Abhishek Dey
- School of Chemical Sciences
- Indian Association for the Cultivation of Science
- Kolkata
- India
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8
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Amanullah S, Dey A. The role of porphyrin peripheral substituents in determining the reactivities of ferrous nitrosyl species. Chem Sci 2020; 11:5909-5921. [PMID: 32832056 PMCID: PMC7407271 DOI: 10.1039/d0sc01625j] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 05/07/2020] [Indexed: 12/02/2022] Open
Abstract
Ferrous nitrosyl {FeNO}7 species is an intermediate common to the catalytic cycles of Cd1NiR and CcNiR, two heme-based nitrite reductases (NiR), and its reactivity varies dramatically in these enzymes.
Ferrous nitrosyl {FeNO}7 species is an intermediate common to the catalytic cycles of Cd1NiR and CcNiR, two heme-based nitrite reductases (NiR), and its reactivity varies dramatically in these enzymes. The former reduces NO2– to NO in the denitrification pathway while the latter reduces NO2– to NH4+ in a dissimilatory nitrite reduction. With very similar electron transfer partners and heme based active sites, the origin of this difference in reactivity has remained unexplained. Differences in the structure of the heme d1 (Cd1NiR), which bears electron-withdrawing groups and has saturated pyrroles, relative to heme c (CcNiR) are often invoked to explain these reactivities. A series of iron porphyrinoids, designed to model the electron-withdrawing peripheral substitution as well as the saturation present in heme d1 in Cd1NiR, and their NO adducts were synthesized and their properties were investigated. The data clearly show that the presence of electron-withdrawing groups (EWGs) and saturated pyrroles together in a synthetic porphyrinoid (FeDEsC) weakens the Fe–NO bond in {FeNO}7 adducts along with decreasing the bond dissociation free energies (BDFENH) of the {FeHNO}8 species. The EWG raises the E° of the {FeNO}7/8 process, making the electron transfer (ET) facile, but decreases the pKa of {FeNO}8 species, making protonation (PT) difficult, while saturation has the opposite effect. The weakening of the Fe–NO bonding biases the {FeNO}7 species of FeDEsC for NO dissociation, as in Cd1NiR, which is otherwise set-up for a proton-coupled electron transfer (PCET) to form an {FeHNO}8 species eventually leading to its further reduction to NH4+.
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Affiliation(s)
- Sk Amanullah
- School of Chemical Sciences , Indian Association for the Cultivation of Science , 2A & 2B Raja SC Mullick Road , Kolkata , India - 700032 .
| | - Abhishek Dey
- School of Chemical Sciences , Indian Association for the Cultivation of Science , 2A & 2B Raja SC Mullick Road , Kolkata , India - 700032 .
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Singha A, Mittra K, Dey A. Effect of hydrogen bonding on innocent and non-innocent axial ligands bound to iron porphyrins. Dalton Trans 2019; 48:7179-7186. [DOI: 10.1039/c8dt03852j] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Most known heme enzymes utilize hydrogen bonding interactions in their active sites to control electronic and geometric structures and the ensuing reactivity.
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Affiliation(s)
- Asmita Singha
- School of Chemical Science
- Indian Association for the Cultivation of Science
- Kolkata
- India
| | - Kaustuv Mittra
- School of Chemical Science
- Indian Association for the Cultivation of Science
- Kolkata
- India
| | - Abhishek Dey
- School of Chemical Science
- Indian Association for the Cultivation of Science
- Kolkata
- India
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Wu LB, Yuan H, Gao SQ, You Y, Nie CM, Wen GB, Lin YW, Tan X. Regulating the nitrite reductase activity of myoglobin by redesigning the heme active center. Nitric Oxide 2016; 57:21-29. [PMID: 27108710 DOI: 10.1016/j.niox.2016.04.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 04/13/2016] [Accepted: 04/20/2016] [Indexed: 10/21/2022]
Abstract
Heme proteins perform diverse functions in living systems, of which nitrite reductase (NIR) activity receives much attention recently. In this study, to better understand the structural elements responsible for the NIR activity, we used myoglobin (Mb) as a model heme protein and redesigned the heme active center, by introducing one or two distal histidines, and by creating a channel to the heme center with removal of the native distal His64 gate (His to Ala mutation). UV-Vis kinetic studies, combined with EPR studies, showed that a single distal histidine with a suitable position to the heme iron, i.e., His43, is crucial for nitrite (NO2(-)) to nitric oxide (NO) reduction. Moreover, creation of a water channel to the heme center significantly enhanced the NIR activity compared to the corresponding mutant without the channel. In addition, X-ray crystallographic studies of F43H/H64A Mb and its complexes with NO2(-) or NO revealed a unique hydrogen-bonding network in the heme active center, as well as unique substrate and product binding models, providing valuable structural information for the enhanced NIR activity. These findings enriched our understanding of the structure and NIR activity relationship of heme proteins. The approach of creating a channel in this study is also useful for rational design of other functional heme proteins.
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Affiliation(s)
- Lei-Bin Wu
- School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China
| | - Hong Yuan
- Department of Chemistry & Institute of Biomedical Science, Fudan University, Shanghai 200433, China
| | - Shu-Qin Gao
- Laboratory of Protein Structure and Function, University of South China, Hengyang 421001, China
| | - Yong You
- Laboratory of Protein Structure and Function, University of South China, Hengyang 421001, China
| | - Chang-Ming Nie
- School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China
| | - Ge-Bo Wen
- Laboratory of Protein Structure and Function, University of South China, Hengyang 421001, China
| | - Ying-Wu Lin
- School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China; Laboratory of Protein Structure and Function, University of South China, Hengyang 421001, China.
| | - Xiangshi Tan
- Department of Chemistry & Institute of Biomedical Science, Fudan University, Shanghai 200433, China.
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Sundararajan M, Neese F. Distal Histidine Modulates the Unusual O-Binding of Nitrite to Myoglobin: Evidence from the Quantum Chemical Analysis of EPR Parameters. Inorg Chem 2015; 54:7209-17. [DOI: 10.1021/acs.inorgchem.5b00557] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mahesh Sundararajan
- Theoretical Chemistry
Section, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Frank Neese
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
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Astashkin AV, Chen L, Elmore BO, Kunwar D, Miao Y, Li H, Poulos TL, Roman LJ, Feng C. Probing the Hydrogen Bonding of the Ferrous-NO Heme Center of nNOS by Pulsed Electron Paramagnetic Resonance. J Phys Chem A 2015; 119:6641-9. [PMID: 26035438 DOI: 10.1021/acs.jpca.5b01804] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Oxidation of L-arginine (L-Arg) to nitric oxide (NO) by NO synthase (NOS) takes place at the heme active site. It is of current interest to study structures of the heme species that activates O2 and transforms the substrate. The NOS ferrous-NO complex is a close mimic of the obligatory ferric (hydro)peroxo intermediate in NOS catalysis. In this work, pulsed electron-nuclear double resonance (ENDOR) spectroscopy was used to probe the hydrogen bonding of the NO ligand in the ferrous-NO heme center of neuronal NOS (nNOS) without a substrate and with L-Arg or N-hydroxy-L-arginine (NOHA) substrates. Unexpectedly, no H-bonding interaction connecting the NO ligand to the active site water molecule or the Arg substrate was detected, in contrast to the results obtained by X-ray crystallography for the Arg-bound nNOS heme domain [Li et al. J. Biol. Inorg. Chem. 2006, 11, 753-768]. The nearby exchangeable proton in both the no-substrate and Arg-containing nNOS samples is located outside the H-bonding range and, on the basis of the obtained structural constraints, can belong to the active site water (or OH). On the contrary, in the NOHA-bound sample, the nearby exchangeable hydrogen forms an H-bond with the NO ligand (on the basis of its distance from the NO ligand and a nonzero isotropic hfi constant), but it does not belong to the active site water molecule because the water oxygen atom (detected by (17)O ENDOR) is too far. This hydrogen should therefore come from the NOHA substrate, which is in agreement with the X-ray crystallography work [Li et al. Biochemistry 2009, 48, 10246-10254]. The nearby nonexchangeable hydrogen atom assigned as H(ε) of Phe584 was detected in all three samples. This hydrogen atom may have a stabilizing effect on the NO ligand and probably determines its position.
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Affiliation(s)
- Andrei V Astashkin
- †Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Li Chen
- ‡College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Bradley O Elmore
- ‡College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Deepak Kunwar
- ‡College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Yubin Miao
- ‡College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Huiying Li
- §Departments of Molecular Biology and Biochemistry, Chemistry, and Pharmaceutical Sciences, University of California, Irvine, Irvine, California 92697-3900, United States
| | - Thomas L Poulos
- §Departments of Molecular Biology and Biochemistry, Chemistry, and Pharmaceutical Sciences, University of California, Irvine, Irvine, California 92697-3900, United States
| | - Linda J Roman
- ∥Department of Biochemistry, University of Texas Health Science Center in San Antonio, San Antonio, Texas 78229, United States
| | - Changjian Feng
- ‡College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States
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He C, Howes BD, Smulevich G, Rumpel S, Reijerse EJ, Lubitz W, Cox N, Knipp M. Nitrite Dismutase Reaction Mechanism: Kinetic and Spectroscopic Investigation of the Interaction between Nitrophorin and Nitrite. J Am Chem Soc 2015; 137:4141-50. [DOI: 10.1021/ja512938u] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Chunmao He
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Barry D. Howes
- Department
of Chemistry “Ugo Schiff”, University of Florence, Via della Lastruccia 3-13, I-50019 Sesto Fiorentino(Fi), Italy
| | - Giulietta Smulevich
- Department
of Chemistry “Ugo Schiff”, University of Florence, Via della Lastruccia 3-13, I-50019 Sesto Fiorentino(Fi), Italy
| | - Sigrun Rumpel
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Edward J. Reijerse
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Wolfgang Lubitz
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Nicholas Cox
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Markus Knipp
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
- Faculty
of Chemistry and Biochemistry, Ruhr University, Universitätsstrasse 150, D-44780 Bochum, Germany
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15
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Rinaldo S, Giardina G, Cutruzzolà F. Nitrosylation of c heme in cd(1)-nitrite reductase is enhanced during catalysis. Biochem Biophys Res Commun 2014; 451:449-54. [PMID: 25117445 DOI: 10.1016/j.bbrc.2014.08.020] [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: 07/25/2014] [Accepted: 08/04/2014] [Indexed: 11/26/2022]
Abstract
The reduction of nitrite into nitric oxide (NO) in denitrifying bacteria is catalyzed by nitrite reductase. In several species, this enzyme is a heme-containing protein with one c heme and one d1 heme per monomer (cd1NiR), encoded by the nirS gene. For many years, the evidence of a link between NO and this hemeprotein represented a paradox, given that NO was known to tightly bind and, possibly, inhibit hemeproteins, including cd1NiRs. It is now established that, during catalysis, cd1NiRs diverge from "canonical" hemeproteins, since the product NO rapidly dissociates from the ferrous d1 heme, which, in turn, displays a peculiar "low" affinity for NO (KD=0.11 μM at pH 7.0). It has been also previously shown that the c heme reacts with NO at acidic pH but c heme nitrosylation was not extensively investigated, given that in cd1NiR it was considered a side reaction, rather than a genuine process controlling catalysis. The spectroscopic study of the reaction of cd1NiR and its semi-apo derivative (containing the sole c heme) with NO reported here shows that c heme nitrosylation is enhanced during catalysis; this evidence has been discussed in order to assess the potential of c heme nitrosylation as a regulatory process, as observed for cytochrome c nitrosylation in mammalian mitochondria.
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Affiliation(s)
- Serena Rinaldo
- Department of Biochemical Sciences and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy.
| | - Giorgio Giardina
- Department of Biochemical Sciences and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
| | - Francesca Cutruzzolà
- Department of Biochemical Sciences and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
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16
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Bali S, Palmer DJ, Schroeder S, Ferguson SJ, Warren MJ. Recent advances in the biosynthesis of modified tetrapyrroles: the discovery of an alternative pathway for the formation of heme and heme d 1. Cell Mol Life Sci 2014; 71:2837-63. [PMID: 24515122 PMCID: PMC11113276 DOI: 10.1007/s00018-014-1563-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 12/19/2013] [Accepted: 01/10/2014] [Indexed: 02/05/2023]
Abstract
Hemes (a, b, c, and o) and heme d 1 belong to the group of modified tetrapyrroles, which also includes chlorophylls, cobalamins, coenzyme F430, and siroheme. These compounds are found throughout all domains of life and are involved in a variety of essential biological processes ranging from photosynthesis to methanogenesis. The biosynthesis of heme b has been well studied in many organisms, but in sulfate-reducing bacteria and archaea, the pathway has remained a mystery, as many of the enzymes involved in these characterized steps are absent. The heme pathway in most organisms proceeds from the cyclic precursor of all modified tetrapyrroles uroporphyrinogen III, to coproporphyrinogen III, which is followed by oxidation of the ring and finally iron insertion. Sulfate-reducing bacteria and some archaea lack the genetic information necessary to convert uroporphyrinogen III to heme along the "classical" route and instead use an "alternative" pathway. Biosynthesis of the isobacteriochlorin heme d 1, a cofactor of the dissimilatory nitrite reductase cytochrome cd 1, has also been a subject of much research, although the biosynthetic pathway and its intermediates have evaded discovery for quite some time. This review focuses on the recent advances in the understanding of these two pathways and their surprisingly close relationship via the unlikely intermediate siroheme, which is also a cofactor of sulfite and nitrite reductases in many organisms. The evolutionary questions raised by this discovery will also be discussed along with the potential regulation required by organisms with overlapping tetrapyrrole biosynthesis pathways.
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Affiliation(s)
- Shilpa Bali
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU UK
| | - David J. Palmer
- School of Biosciences, University of Kent, Kent, Canterbury, CT2 7NZ UK
| | - Susanne Schroeder
- School of Biosciences, University of Kent, Kent, Canterbury, CT2 7NZ UK
| | - Stuart J. Ferguson
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU UK
| | - Martin J. Warren
- School of Biosciences, University of Kent, Kent, Canterbury, CT2 7NZ UK
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17
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Affiliation(s)
- Luisa B. Maia
- REQUIMTE/CQFB, Departamento
de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - José J. G. Moura
- REQUIMTE/CQFB, Departamento
de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
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18
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Blomberg MRA, Borowski T, Himo F, Liao RZ, Siegbahn PEM. Quantum chemical studies of mechanisms for metalloenzymes. Chem Rev 2014; 114:3601-58. [PMID: 24410477 DOI: 10.1021/cr400388t] [Citation(s) in RCA: 431] [Impact Index Per Article: 43.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Margareta R A Blomberg
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University , SE-106 91 Stockholm, Sweden
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19
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Goodrich LE, Roy S, Alp EE, Zhao J, Hu MY, Lehnert N. Electronic Structure and Biologically Relevant Reactivity of Low-Spin {FeNO}8 Porphyrin Model Complexes: New Insight from a Bis-Picket Fence Porphyrin. Inorg Chem 2013; 52:7766-80. [DOI: 10.1021/ic400977h] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lauren E. Goodrich
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109,
United States
| | - Saikat Roy
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109,
United States
| | - E. Ercan Alp
- Advanced
Photon Source, Argonne National Laboratory, Argonne, Illinois 60439,
United States
| | - Jiyong Zhao
- Advanced
Photon Source, Argonne National Laboratory, Argonne, Illinois 60439,
United States
| | - Michael Y. Hu
- Advanced
Photon Source, Argonne National Laboratory, Argonne, Illinois 60439,
United States
| | - Nicolai Lehnert
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109,
United States
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20
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Lehnert N, Scheidt WR, Wolf MW. Structure and Bonding in Heme–Nitrosyl Complexes and Implications for Biology. NITROSYL COMPLEXES IN INORGANIC CHEMISTRY, BIOCHEMISTRY AND MEDICINE II 2013. [DOI: 10.1007/430_2013_92] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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21
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Radoul M, Barak Y, Rinaldo S, Cutruzzolà F, Pecht I, Goldfarb D. Solvent accessibility in the distal heme pocket of the nitrosyl d(1)-heme complex of Pseudomonas stutzeri cd(1) nitrite reductase. Biochemistry 2012; 51:9192-201. [PMID: 23072349 DOI: 10.1021/bi3011237] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In nitrite reductase (cd(1) NIR), the c-heme mediates electron transfer to the catalytic d(1)-heme where nitrite (NO(2)(-)) is reduced to nitric oxide (NO). An interesting feature of this enzyme is the relative lability of the reaction product NO bound to the d(1)-heme. Marked differences in the c- to d(1)-heme electron-transfer rates were reported for cd(1) NIRs from different sources, such as Pseudomonas stutzeri (P. stutzeri) and Pseudomonas aeruginosa (P. aeruginosa). The three-dimensional structure of the P. aeruginosa enzyme has been determined, but that of the P. stutzeri enzyme is still unknown. The difference in electron transfer rates prompted a comparison of the structural properties of the d(1)-heme pocket of P. stutzeri cd(1) NIR with those of the P. aeruginosa wild type enzyme (WT) and its Y10F using their nitrosyl d(1)-heme complexes. We applied high field pulse electron paramagnetic resonance (EPR) techniques that detect nuclear spins in the close environment of the spin bearing Fe(II)-NO entity. We observed similarities in the rhombic g-tensor and detected a proximal histidine ligand with (14)N hyperfine and quadrupole interactions also similar to those of P. aeruginosa WT and Y10F mutant complexes. In contrast, we also observed significant differences in the H-bond network involving the NO ligand and a larger solvent accessibility for P. stutzeri attributed to the absence of this tyrosine residue. For P. aeruginosa, cd(1) NIR domain swapping allows Tyr(10) to become H-bonded to the bound NO substrate. These findings support a previous suggestion that the large difference in the c- to d(1)-heme electron transfer rates between the two enzymes is related to solvent accessibility of their d(1)-heme pockets.
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Affiliation(s)
- Marina Radoul
- Department of Chemical Physics, Weizmann Institute of Science, Israel
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22
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Argirević T, Riplinger C, Stubbe J, Neese F, Bennati M. ENDOR spectroscopy and DFT calculations: evidence for the hydrogen-bond network within α2 in the PCET of E. coli ribonucleotide reductase. J Am Chem Soc 2012; 134:17661-70. [PMID: 23072506 PMCID: PMC4516058 DOI: 10.1021/ja3071682] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Escherichia coli class I ribonucleotide reductase (RNR) catalyzes the conversion of nucleotides to deoxynucleotides and is composed of two subunits: α2 and β2. β2 contains a stable di-iron tyrosyl radical (Y(122)(•)) cofactor required to generate a thiyl radical (C(439)(•)) in α2 over a distance of 35 Å, which in turn initiates the chemistry of the reduction process. The radical transfer process is proposed to occur by proton-coupled electron transfer (PCET) via a specific pathway: Y(122) ⇆ W(48)[?] ⇆ Y(356) in β2, across the subunit interface to Y(731) ⇆ Y(730) ⇆ C(439) in α2. Within α2 a colinear PCET model has been proposed. To obtain evidence for this model, 3-amino tyrosine (NH(2)Y) replaced Y(730) in α2, and this mutant was incubated with β2, cytidine 5'-diphosphate, and adenosine 5'-triphosphate to generate a NH(2)Y(730)(•) in D(2)O. [(2)H]-Electron-nuclear double resonance (ENDOR) spectra at 94 GHz of this intermediate were obtained, and together with DFT models of α2 and quantum chemical calculations allowed assignment of the prominent ENDOR features to two hydrogen bonds likely associated with C(439) and Y(731). A third proton was assigned to a water molecule in close proximity (2.2 Å O-H···O distance) to residue 730. The calculations also suggest that the unusual g-values measured for NH(2)Y(730)(•) are consistent with the combined effect of the hydrogen bonds to Cys(439) and Tyr(731), both nearly perpendicular to the ring plane of NH(2)Y(730.) The results provide the first experimental evidence for the hydrogen-bond network between the pathway residues in α2 of the active RNR complex, for which no structural data are available.
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Affiliation(s)
- Tomislav Argirević
- Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Christoph Riplinger
- Max Planck Institute for Chemical Energy Conversion, 45470 Mülheim an der Ruhr, Germany
| | - JoAnne Stubbe
- Dept. of Chemistry and Biology, MIT, Cambridge, MA 02139, USA
| | - Frank Neese
- Max Planck Institute for Chemical Energy Conversion, 45470 Mülheim an der Ruhr, Germany
| | - Marina Bennati
- Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
- Dept. of Chemistry, University of Göttingen, 37077 Göttingen, Germany
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23
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Gunn A, Derbyshire ER, Marletta MA, Britt RD. Conformationally distinct five-coordinate heme-NO complexes of soluble guanylate cyclase elucidated by multifrequency electron paramagnetic resonance (EPR). Biochemistry 2012; 51:8384-90. [PMID: 22985445 DOI: 10.1021/bi300831m] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Soluble guanylate cyclase (sGC) is a heme-containing enzyme that senses nitric oxide (NO). Formation of a heme Fe-NO complex is essential to sGC activation, and several spectroscopic techniques, including electron paramagnetic resonance (EPR) spectroscopy, have been aimed at elucidating the active enzyme conformation. Of these, only EPR spectra (X-band ~9.6 GHz) have shown differences between low- and high-activity Fe-NO states, and these states are modeled in two different heme domain truncations of sGC, β1(1-194) and β2(1-217), respectively (Derbyshire et al., Biochemistry 2008, 47, 3892-3899). The EPR signal of the low-activity sGC Fe-NO complex exhibits a broad lineshape that has been interpreted as resulting from site-to-site inhomogeneity, and simulated using g strain, a continuous distribution about the principal values of a given g tensor. This approach, however, fails to account for visible features in the X-band EPR spectra as well as the g anisotropy observed at higher microwave frequencies. Herein we analyze X-, Q-, and D-band EPR spectra and show that both the broad lineshape and the spectral structure of the sGC EPR signal at multiple microwave frequencies can be simulated successfully with a superposition of only two distinct g tensors. These tensors represent different populations that likely differ in Fe-NO bond angle, hydrogen bonding, or the geometry of the amino acid residues. One of these conformations can be linked to a form of the enzyme with higher activity.
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Affiliation(s)
- Alexander Gunn
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
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24
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Bhuyan J, Sarkar S. Nitrous‐Acid‐Mediated Synthesis of Iron–Nitrosyl–Porphyrin: pH‐Dependent Release of Nitric Oxide. Chem Asian J 2012; 7:2690-5. [DOI: 10.1002/asia.201200518] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 07/01/2012] [Indexed: 11/07/2022]
Affiliation(s)
- Jagannath Bhuyan
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur‐208016, U.P. (India)
| | - Sabyasachi Sarkar
- Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah‐711103 (West Bengal)
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25
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Astashkin AV, Elmore BO, Chen L, Fan W, Guillemette JG, Feng C. Pulsed ENDOR determination of the arginine location in the ferrous-NO form of neuronal NOS. J Phys Chem A 2012; 116:6731-9. [PMID: 22667467 DOI: 10.1021/jp302319c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Mammalian nitric oxide synthases (NOSs) are enzymes responsible for oxidation of L-arginine (L-Arg) to nitric oxide (NO). Mechanisms of reactions at the catalytic heme site are not well understood, and it is of current interest to study structures of the heme species that activates O(2) and transforms the substrate. The NOS ferrous-NO complex is a close mimic of the obligatory ferric (hydro)peroxo intermediate in NOS catalysis. In this work, pulsed electron-nuclear double resonance (ENDOR) was used to probe the position of the l-Arg substrate at the NO(•)-coordinated ferrous heme center(s) in the oxygenase domain of rat neuronal NOS (nNOS). The analysis of (2)H and (15)N ENDOR spectra of samples containing d(7)- or guanidino-(15)N(2) labeled L-Arg has resulted in distance estimates for the nearby guanidino nitrogen and the nearby proton (deuteron) at C(δ). The L-Arg position was found to be noticeably different from that in the X-ray crystal structure of nNOS ferrous-NO complex [Li et al. J. Biol. Inorg. Chem.2006, 11, 753-768], with the nearby guanidino nitrogen being ~0.5 Å closer to, and the nearby H(δ) about 1 Å further from, the NO ligand than in the X-ray structure. The difference might be related to the structural constraints imposed on the protein by the crystal. Importantly, in spite of its closer position, the guanidino nitrogen does not form a hydrogen bond with the NO ligand, as evidenced by the absence of significant isotropic hfi constant for N(g1). This is consistent with the previous reports that it is not the L-Arg substrate itself that would most likely serve as a direct proton donor to the diatomic ligands (NO and O(2)) bound to the heme.
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Affiliation(s)
- Andrei V Astashkin
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, USA
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26
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Lin YW, Nie CM, Liao LF. Rational design of a nitrite reductase based on myoglobin: a molecular modeling and dynamics simulation study. J Mol Model 2012; 18:4409-15. [DOI: 10.1007/s00894-012-1451-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Accepted: 04/30/2012] [Indexed: 10/28/2022]
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27
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Zhang K, Lam KF, Albela B, Xue T, Khrouz L, Hou QW, Yuan EH, He MY, Bonneviot L. Mononuclear-dinuclear equilibrium of grafted copper complexes confined in the nanochannels of MCM-41 silica. Chemistry 2011; 17:14258-66. [PMID: 22068981 DOI: 10.1002/chem.201102026] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Indexed: 11/11/2022]
Abstract
Following the structural concept of copper-containing proteins in which dinuclear copper centers are connected by hydroxide bridging ligands, a bidentate copper(II) complex has been incorporated into nano-confined MCM-41 silica by a multistep sequential grafting technique. Characterization by a combination of EPR spectroscopy, X-ray photoelectron spectroscopy (XPS), UV/Vis spectroscopy, IR spectroscopy , and solid-state (13)C and (29)Si cross-polarization magic-angle spinning (CP-MAS) NMR suggests that dinuclear Cu complexes are bridged by hydroxide and other counterions (chloride or perchlorate ions), similar to the situation for EPR-undetectable [Cu(II)···Cu(II)] dimer analogues in biological systems. More importantly, a dynamic mononuclear-dinuclear equilibrium between different coordination modes of copper is observed, which strongly depends on the nature of the counterions (Cl(-) or ClO(4)(-)) in the copper precursor and the pore size of the silica matrix (the so-called confinement effect). A proton-transfer mechanism within the hydrogen-bonding network is suggested to explain the dynamic nature of the dinuclear copper complex supported on the MCM-41 silica.
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Affiliation(s)
- Kun Zhang
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, 3663 Zhongshan North Road, 200062, Shanghai, China.
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