1
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Levitz TS, Drennan CL. Starting a new chapter on class Ia ribonucleotide reductases. Curr Opin Struct Biol 2022; 77:102489. [PMID: 36272229 DOI: 10.1016/j.sbi.2022.102489] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 09/13/2022] [Accepted: 09/16/2022] [Indexed: 01/21/2023]
Abstract
Ribonucleotide reductases (RNRs) use radical-based chemistry to convert ribonucleotides into deoxyribonucleotides, an essential step in DNA biosynthesis and repair. There are multiple RNR classes, the best studied of which is the class Ia RNR that is found in Escherichia coli, eukaryotes including humans, and many pathogenic and nonpathogenic prokaryotes. This review covers recent advances in our understanding of class Ia RNRs, including a recent reporting of a structure of the active state of the E. coli enzyme and the impacts that the structure has had on spurring research into the mechanism of long-range radical transfer. Additionally, the review considers other recent structural and biochemical research on class Ia RNRs and the potential of that work for the development of anticancer and antibiotic therapeutics.
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Affiliation(s)
- Talya S Levitz
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA. https://twitter.com/@TalyaLevitz
| | - Catherine L Drennan
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
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2
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Kamal Hossain M, Davidson M, Feehan J, Deraos G, Nurgali K, Matsoukas J, Apostolopoulos V. Development and characterization of a novel conjugated methamphetamine vaccine. Vaccine 2022; 40:5882-5891. [PMID: 36041942 DOI: 10.1016/j.vaccine.2022.08.043] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 06/09/2022] [Accepted: 08/18/2022] [Indexed: 02/07/2023]
Abstract
BACKGROUND Methamphetamine (METH) addiction is a major public health concern globally with limited management options. The development of a METH vaccine through hapten design has received significant attention as a promising platform for the potential treatment of METH addiction and overdose, however there is yet to be a successful candidate in human trials. RESEARCH DESIGN AND METHODS In this study, we developed a novel conjugated METH vaccine using oxidized mannan (a polymannose) as an immunogenic carrier. A METH hapten was synthesized by using amphetamine and conjugated to mannan with a (Lysine-Glycine-Lysine-Glycine-lysine-Glycine-Lysine-Glycine-Lysine-Glycine) (KG)5 peptide linker. RESULTS The reaction between amphetamine and (KG)5, oxidation of mannan, and conjugation of amphetamine-(KG)5 with oxidized mannan were confirmed by color tests, Fourier-transform infrared spectroscopy, gas and liquid chromatography mass spectrometry, thin-layer chromatography, and ultraviolet spectrophotometer. Additionally, the ability of the vaccine to generate antibodies was confirmed in C57BL/6 mice. CONCLUSIONS The successful development and characterization of the METH-mannan conjugate vaccine, provides a potential therapeutic intervention to curb METH substance use disorders. Each step of vaccine development was characterized to aid in future research on these vaccines, and the immunogenicity shown in the animal models supports future evaluation of the approach. Future studies of the conjugated METH vaccine should evaluate the efficacy in animal models of acute and chronic METH to pave the way for human studies.
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Affiliation(s)
- Md Kamal Hossain
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia
| | - Majid Davidson
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia
| | - Jack Feehan
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia.
| | | | - Kulmira Nurgali
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia
| | - John Matsoukas
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia; Newdrug, Patras Science Park, 26500 Patras, Greece; Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Alberta, AB T2N 4N1, Canada
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3
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Thurnauer MC, Britt RD. In memoriam of Professor Bridgette Barry (March 1, 1957-January 20, 2021). PHOTOSYNTHESIS RESEARCH 2022; 152:91-93. [PMID: 35969321 DOI: 10.1007/s11120-022-00929-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We remember our colleague and friend, Bridgette Barry. Bridgette's numerous seminal contributions to photosynthesis research, beginning with her discovery that two functionally differentiated, redox active tyrosines are involved with the action of the oxygen-evolving complex, continue to impact studies of Photosystem II in laboratories around the world. Dr. Barry was widely recognized for employing clever adaptations of spectroscopic tools to probe unique experimental systems. Taken as a whole, she developed an in depth understanding of how biological proton coupled electron transfer reactions are subject to exquisite control over direction and kinetics. Bridgette dedicated significant time and energy in service to the scientific community. She was committed to her lab members and cared deeply that they each achieve their goals. She was an important role model and promoted women in her department and beyond. Bridgette will be deeply missed by the international scientific community and by those of us who had the honor to know her.
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Affiliation(s)
- Marion C Thurnauer
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL, 60439, USA.
| | - R David Britt
- Department of Chemistry, University of California Davis, Davis, CA, 95615, USA
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4
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Stanojlovic V, Müller A, Moazzam A, Hinterholzer A, Ożga K, Berlicki Ł, Schubert M, Cabrele C. A Conformationally Stable Acyclic β-Hairpin Scaffold Tolerating the Incorporation of Poorly β-Sheet-Prone Amino Acids. Chembiochem 2022; 23:e202100604. [PMID: 34856053 PMCID: PMC9299858 DOI: 10.1002/cbic.202100604] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 11/30/2021] [Indexed: 11/09/2022]
Abstract
The β-hairpin is a structural element of native proteins, but it is also a useful artificial scaffold for finding lead compounds to convert into peptidomimetics or non-peptide structures for drug discovery. Since linear peptides are synthetically more easily accessible than cyclic ones, but are structurally less well-defined, we propose XWXWXpPXK(/R)X(R) as an acyclic but still rigid β-hairpin scaffold that is robust enough to accommodate different types of side chains, regardless of the secondary-structure propensity of the X residues. The high conformational stability of the scaffold results from tight contacts between cross-strand cationic and aromatic side chains, combined with the strong tendency of the d-Pro-l-Pro dipeptide to induce a type II' β-turn. To demonstrate the robustness of the scaffold, we elucidated the NMR structures and performed molecular dynamics (MD) simulations of a series of peptides displaying mainly non-β-branched, poorly β-sheet-prone residues at the X positions. Both the NMR and MD data confirm that our acyclic β-hairpin scaffold is highly versatile as regards the amino-acid composition of the β-sheet face opposite to the cationic-aromatic one.
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Affiliation(s)
- Vesna Stanojlovic
- Department of BiosciencesUniversity of SalzburgHellbrunnerstrasse 345020SalzburgAustria
| | - Anna Müller
- Department of BiosciencesUniversity of SalzburgHellbrunnerstrasse 345020SalzburgAustria
| | - Ali Moazzam
- Department of BiosciencesUniversity of SalzburgHellbrunnerstrasse 345020SalzburgAustria
- School of ChemistryCollege of ScienceUniversity of TehranP.O. Box 14155–6619TehranIran
| | - Arthur Hinterholzer
- Department of BiosciencesUniversity of SalzburgHellbrunnerstrasse 345020SalzburgAustria
| | - Katarzyna Ożga
- Department of Bioorganic ChemistryFaculty of ChemistryWrocław University of Science and TechnologyWybrzeże Wyspiańskiego 2750-370WrocławPoland
| | - Łukasz Berlicki
- Department of Bioorganic ChemistryFaculty of ChemistryWrocław University of Science and TechnologyWybrzeże Wyspiańskiego 2750-370WrocławPoland
| | - Mario Schubert
- Department of BiosciencesUniversity of SalzburgHellbrunnerstrasse 345020SalzburgAustria
| | - Chiara Cabrele
- Department of BiosciencesUniversity of SalzburgHellbrunnerstrasse 345020SalzburgAustria
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5
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Chiş V, Vinţeler E. Excitation energies for anionic drugs predicted by PBE0, TPSS and τHCTH density functionals. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.131120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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6
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Bin Mohd Yusof MS, Lim YL, Loh ZH. Ultrafast vibrational wave packet dynamics of the aqueous tyrosyl radical anion induced by photodetachment. Phys Chem Chem Phys 2021; 23:18525-18534. [PMID: 34581329 DOI: 10.1039/d1cp02975d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The ultrafast dynamics triggered by the photodetachment of the tyrosinate dianion in aqueous environment shed light on the elementary processes that accompany the interaction of ionizing radiation with biological matter. Photodetachment of the tryosinate dianion yields the tyrosyl radical anion, an important intermediate in biological redox reactions, although the study of its ultrafast dynamics is limited. Here, we utilize femtosecond optical pump-probe spectroscopy to investigate the ultrafast structural reorganization dynamics that follow the photodetachment of the tyrosinate dianion in aqueous solution. Photodetachment of the tyrosinate dianion leads to vibrational wave packet motion along seven vibrational modes that are coupled to the photodetachment process. The vibrational modes are assigned with the aid of density functional theory (DFT) calculations. Our results offer a glimpse of the elementary dynamics of ionized biomolecules and suggest the possibility of extending this approach to investigate the ionization-induced structural rearrangement of other aromatic amino acids and larger biomolecules.
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Affiliation(s)
- Muhammad Shafiq Bin Mohd Yusof
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
| | - Yong Liang Lim
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
| | - Zhi-Heng Loh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
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7
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Ru X, Crane BR, Zhang P, Beratan DN. Why Do Most Aromatics Fail to Support Hole Hopping in the Cytochrome c Peroxidase-Cytochrome c Complex? J Phys Chem B 2021; 125:7763-7773. [PMID: 34235935 DOI: 10.1021/acs.jpcb.1c05064] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Electron transport through aromatic species (especially tryptophan and tyrosine) plays a central role in water splitting, redox signaling, oxidative damage protection, and bioenergetics. The cytochrome c peroxidase (CcP)-cytochrome c (Cc) complex (CcP:Cc) is used widely to study interprotein electron transfer (ET) mechanisms. Tryptophan 191 (Trp191) of CcP supports hole hopping charge recombination in the CcP:Cc complex. Experimental studies find that when Trp191 is substituted by tyrosine, phenylalanine, or redox-active aniline derivatives bound in the W191G cavity, enzymatic activity and charge recombination rates both decrease. Theoretical analysis of these CcP:Cc complexes finds that the ET kinetics depend strongly on the chemistry of the modified Trp site. The computed electronic couplings in the W191F and W191G species are orders of magnitude smaller than in the native protein, due largely to the absence of a hopping intermediate and the large tunneling distance. Small molecules bound in the W191G cavity are weakly coupled electronically to the Cc heme, and the structural disorder of the guest molecule in the binding pocket may contribute further to the lack of enzymatic activity. The couplings in W191Y are not substantially weakened compared to the native species, but the redox potential difference for tyrosine vs tryptophan oxidation accounts for the slower rate in the Tyr mutant. Thus, theoretical analysis explains why only the native Trp supports rapid hole hopping in the CcP:Cc complex. Favorable free energies and electronic couplings are essential for establishing an efficient hole hopping relay in this protein-protein complex.
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Affiliation(s)
- Xuyan Ru
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Brian R Crane
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Peng Zhang
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - David N Beratan
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States.,Department of Biochemistry, Duke University, Durham, North Carolina 27710, United States.,Department of Physics, Duke University, Durham, North Carolina 27708, United States
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8
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da Silva FF, Cunha T, Rebelo A, Gil A, Calhorda MJ, García G, Ingólfsson O, Limão-Vieira P. Electron-Transfer-Induced Side-Chain Cleavage in Tryptophan Facilitated through Potassium-Induced Transition-State Stabilization in the Gas Phase. J Phys Chem A 2021; 125:2324-2333. [DOI: 10.1021/acs.jpca.1c00690] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Filipe Ferreira da Silva
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - Tiago Cunha
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - Andre Rebelo
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - Adrià Gil
- BioISI -Biosystems & Integrative Sciences Institute, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
- CIC nanoGUNE BRTA, Tolosa Hiribidea, 76, E-20018 Donostia − San Sebastián, Euskadi, Spain
| | - Maria José Calhorda
- BioISI -Biosystems & Integrative Sciences Institute, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Gustavo García
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas (CSIC), Serrano 113-bis, 28006 Madrid, Spain
| | - Oddur Ingólfsson
- Chemistry and Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavik, Iceland
| | - Paulo Limão-Vieira
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
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9
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The Use of Electrochemical Voltammetric Techniques and High-Pressure Liquid Chromatography to Evaluate Conjugation Efficiency of Multiple Sclerosis Peptide-Carrier Conjugates. Brain Sci 2020; 10:brainsci10090577. [PMID: 32825557 PMCID: PMC7565688 DOI: 10.3390/brainsci10090577] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/10/2020] [Accepted: 08/17/2020] [Indexed: 01/02/2023] Open
Abstract
Recent studies have shown the ability of electrochemical methods to sense and determine, even at very low concentrations, the presence and quantity of molecules or analytes including pharmaceutical samples. Furthermore, analytical methods, such as high-pressure liquid chromatography (HPLC), can also detect the presence and quantity of peptides at very low concentrations, in a simple, fast, and efficient way, which allows the monitoring of conjugation reactions and its completion. Graphite/SiO2 film electrodes and HPLC methods were previously shown by our group to be efficient to detect drug molecules, such as losartan. We now use these methods to detect the conjugation efficiency of a peptide from the immunogenic region of myelin oligodendrocyte to a carrier, mannan. The HPLC method furthermore confirms the stability of the peptide with time in a simple one pot procedure. Our study provides a general method to monitor, sense and detect the presence of peptides by effectively confirming the conjugation efficiency. Such methods can be used when designing conjugates as potential immunotherapeutics in the treatment of diseases, including multiple sclerosis.
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10
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Cruzeiro VWD, Feliciano GT, Roitberg AE. Exploring Coupled Redox and pH Processes with a Force-Field-Based Approach: Applications to Five Different Systems. J Am Chem Soc 2020; 142:3823-3835. [PMID: 32011132 DOI: 10.1021/jacs.9b11433] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Coupled redox and pH-driven processes are at the core of many important biological mechanisms. As the distribution of protonation and redox states in a system is associated with the pH and redox potential of the solution, having efficient computational tools that can simulate under these conditions becomes very important. Such tools have the potential to provide information that complement and drive experiments. In previous publications we have presented the implementation of the constant pH and redox potential molecular dynamics (C(pH,E)MD) method in AMBER and we have shown how multidimensional replica exchange can be used to significantly enhance the convergence efficiency of our simulations. In the current work, after an improvement in our C(pH,E)MD approach that allows a given residue to be simultaneously pH- and redox-active, we have employed our methodologies to study five different systems of interest in the literature. We present results for capped tyrosine dipeptide, two maquette systems containing one pH- and redox-active tyrosine (α3Y and peptide A), and two proteins that contain multiple heme groups (diheme cytochrome c from Rhodobacter sphaeroides and Desulfovibrio vulgaris Hildenborough cytochrome c3). We show that our results can provide new insights into previous theoretical and experimental findings by using a fully force-field-based and GPU-accelerated approach, which allows the simulations to be executed with high computational performance.
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Affiliation(s)
| | - Gustavo Troiano Feliciano
- Departamento de Físico-Química, Instituto de Química , Universidade Estadual Paulista (Unesp) , Araraquara , Brazil
| | - Adrian E Roitberg
- Department of Chemistry , University of Florida , Gainesville , Florida 32611 , United States
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11
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McCaslin TG, Pagba CV, Hwang H, Gumbart JC, Chi SH, Perry JW, Barry BA. Tyrosine, cysteine, and proton coupled electron transfer in a ribonucleotide reductase-inspired beta hairpin maquette. Chem Commun (Camb) 2019; 55:9399-9402. [PMID: 31322154 DOI: 10.1039/c9cc04067f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Tyrosine residues act as intermediates in proton coupled electron transfer reactions (PCET) in proteins. For example, in ribonucleotide reductase (RNR), a tyrosyl radical oxidizes an active site cysteine via a 35 Å pathway that contains multiple aromatic groups. When singlet tyrosine is oxidized, the radical becomes a strong acid, and proton transfer reactions, which are coupled with the redox reaction, may be used to control reaction rate. Here, we characterize a tyrosine-containing beta hairpin, Peptide O, which has a cross-strand, noncovalent interaction between its single tyrosine, Y5, and a cysteine (C14). Circular dichroism provides evidence for a thermostable beta-turn. EPR spectroscopy shows that Peptide O forms a neutral tyrosyl radical after UV photolysis at 160 K. Molecular dynamics simulations support a phenolic/SH interaction in the tyrosine singlet and radical states. Differential pulse voltammetry exhibits pH dependence consistent with the formation of a neutral tyrosyl radical and a pKa change in two other residues. A redox-coupled decrease in cysteine pKa from 9 (singlet) to 6.9 (radical) is assigned. At pD 11, picosecond transient absorption spectroscopy after UV photolysis monitors tyrosyl radical recombination via electron transfer (ET). The ET rate in Peptide O is indistinguishable from the ET rates observed in peptides containing a histidine and a cyclohexylalanine (Cha) at position 14. However, at pD 9, the tyrosyl radical decays via PCET, and the decay rate is slowed, when compared to the histidine 14 variant. Notably, the decay rate is accelerated, when compared to the Cha 14 variant. We conclude that redox coupling between tyrosine and cysteine can act as a PCET control mechanism in proteins.
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Affiliation(s)
- Tyler G McCaslin
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA. and The Parker H. Petit Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Cynthia V Pagba
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA. and The Parker H. Petit Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Hyea Hwang
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - James C Gumbart
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA. and The Parker H. Petit Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA and School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - San-Hui Chi
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA. and Center of Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Joseph W Perry
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA. and Center of Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Bridgette A Barry
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA. and The Parker H. Petit Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
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12
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McCaslin TG, Pagba CV, Chi SH, Hwang HJ, Gumbart JC, Perry JW, Olivieri C, Porcelli F, Veglia G, Guo Z, McDaniel M, Barry BA. Structure and Function of Tryptophan-Tyrosine Dyads in Biomimetic β Hairpins. J Phys Chem B 2019; 123:2780-2791. [PMID: 30888824 PMCID: PMC6463897 DOI: 10.1021/acs.jpcb.8b12452] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
![]()
Tyrosine–tryptophan (YW) dyads
are ubiquitous
structural motifs in enzymes and play roles in proton-coupled electron
transfer (PCET) and, possibly, protection from oxidative stress. Here,
we describe the function of YW dyads in de novo designed 18-mer, β
hairpins. In Peptide M, a YW dyad is formed between W14 and Y5. A
UV hypochromic effect and an excitonic Cotton signal are observed,
in addition to singlet, excited state (W*) and fluorescence emission
spectral shifts. In a second Peptide, Peptide MW, a Y5–W13
dyad is formed diagonally across the strand and distorts the backbone.
On a picosecond timescale, the W* excited-state decay kinetics are
similar in all peptides but are accelerated relative to amino acids
in solution. In Peptide MW, the W* spectrum is consistent with increased
conformational flexibility. In Peptide M and MW, the electron paramagnetic
resonance spectra obtained after UV photolysis are characteristic
of tyrosine and tryptophan radicals at 160 K. Notably, at pH 9, the
radical photolysis yield is decreased in Peptide M and MW, compared
to that in a tyrosine and tryptophan mixture. This protective effect
is not observed at pH 11 and is not observed in peptides containing
a tryptophan–histidine dyad or tryptophan alone. The YW dyad
protective effect is attributed to an increase in the radical recombination
rate. This increase in rate can be facilitated by hydrogen-bonding
interactions, which lower the barrier for the PCET reaction at pH
9. These results suggest that the YW dyad structural motif promotes
radical quenching under conditions of reactive oxygen stress.
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Affiliation(s)
| | | | | | | | | | | | | | - Fernando Porcelli
- Department for Innovation in Biological, Agro-Food and Forest Systems , University of Tuscia , 01100 Viterbo , Italy
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13
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Lee J, Ju M, Cho OH, Kim Y, Nam KT. Tyrosine-Rich Peptides as a Platform for Assembly and Material Synthesis. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1801255. [PMID: 30828522 PMCID: PMC6382316 DOI: 10.1002/advs.201801255] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 09/27/2018] [Indexed: 05/27/2023]
Abstract
The self-assembly of biomolecules can provide a new approach for the design of functional systems with a diverse range of hierarchical nanoarchitectures and atomically defined structures. In this regard, peptides, particularly short peptides, are attractive building blocks because of their ease of establishing structure-property relationships, their productive synthesis, and the possibility of their hybridization with other motifs. Several assembling peptides, such as ionic-complementary peptides, cyclic peptides, peptide amphiphiles, the Fmoc-peptide, and aromatic dipeptides, are widely studied. Recently, studies on material synthesis and the application of tyrosine-rich short peptide-based systems have demonstrated that tyrosine units serve as not only excellent assembly motifs but also multifunctional templates. Tyrosine has a phenolic functional group that contributes to π-π interactions for conformation control and efficient charge transport by proton-coupled electron-transfer reactions in natural systems. Here, the critical roles of the tyrosine motif with respect to its electrochemical, chemical, and structural properties are discussed and recent discoveries and advances made in tyrosine-rich short peptide systems from self-assembled structures to peptide/inorganic hybrid materials are highlighted. A brief account of the opportunities in design optimization and the applications of tyrosine peptide-based biomimetic materials is included.
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Affiliation(s)
- Jaehun Lee
- Department of Materials Science and EngineeringSeoul National UniversitySeoul08826Republic of Korea
| | - Misong Ju
- Department of Materials Science and EngineeringSeoul National UniversitySeoul08826Republic of Korea
| | - Ouk Hyun Cho
- Department of Materials Science and EngineeringSeoul National UniversitySeoul08826Republic of Korea
| | - Younghye Kim
- Department of Materials Science and EngineeringSeoul National UniversitySeoul08826Republic of Korea
| | - Ki Tae Nam
- Department of Materials Science and EngineeringSeoul National UniversitySeoul08826Republic of Korea
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14
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Jiang L, Xu Y, Zhang P, Zhang Y, Li H, Chen J, Liu S, Zeng Q. Functional MoS2 nanosheets inhibit melanogenesis to enhance UVB/X-ray induced damage. J Mater Chem B 2019. [DOI: 10.1039/c9tb00419j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We produced highly dispersed MoS2 nanosheets in water with the assistance of tryptophan (Trp) to inhibit melanogenesis by suppressing ROS production.
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Affiliation(s)
- Ling Jiang
- Department of Dermatology
- Third Xiangya Hospital
- Central South University
- Changsha
- China
| | - Yanyan Xu
- Institute of Chemical Biology and Nanomedicine (ICBN)
- State Key Laboratory of Chemo/Biosensing and Chemometrics
- College of Biology
- College of Chemistry and Chemical Engineering
- Hunan University
| | - Pei Zhang
- Institute of Chemical Biology and Nanomedicine (ICBN)
- State Key Laboratory of Chemo/Biosensing and Chemometrics
- College of Biology
- College of Chemistry and Chemical Engineering
- Hunan University
| | - Yi Zhang
- Hunan Key Lab of Mineral Materials and Application
- Central South University
- Changsha
- China
- School of Minerals Processing and Bioengineering
| | - Huimin Li
- Institute of Chemical Biology and Nanomedicine (ICBN)
- State Key Laboratory of Chemo/Biosensing and Chemometrics
- College of Biology
- College of Chemistry and Chemical Engineering
- Hunan University
| | - Jing Chen
- Department of Dermatology
- Third Xiangya Hospital
- Central South University
- Changsha
- China
| | - Song Liu
- Institute of Chemical Biology and Nanomedicine (ICBN)
- State Key Laboratory of Chemo/Biosensing and Chemometrics
- College of Biology
- College of Chemistry and Chemical Engineering
- Hunan University
| | - Qinghai Zeng
- Department of Dermatology
- Third Xiangya Hospital
- Central South University
- Changsha
- China
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15
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Design and structural characterisation of monomeric water-soluble α-helix and β-hairpin peptides: State-of-the-art. Arch Biochem Biophys 2019; 661:149-167. [DOI: 10.1016/j.abb.2018.11.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 11/06/2018] [Accepted: 11/14/2018] [Indexed: 02/06/2023]
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16
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Macha P, Perreault L, Hamedani Y, Mayes ML, Vasudev MC. Molecular Mechanisms of Tryptophan–Tyrosine Nanostructures Formation and their Influence on PC-12 Cells. ACS APPLIED BIO MATERIALS 2018; 1:1266-1275. [DOI: 10.1021/acsabm.8b00121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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17
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Gillet N, Elstner M, Kubař T. Coupled-perturbed DFTB-QM/MM metadynamics: Application to proton-coupled electron transfer. J Chem Phys 2018; 149:072328. [PMID: 30134697 DOI: 10.1063/1.5027100] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a new concept of free energy calculations of chemical reactions by means of extended sampling molecular dynamics simulations. Biasing potentials are applied on partial atomic charges, which may be combined with atomic coordinates either in a single collective variable or in multi-dimensional biasing simulations. The necessary additional gradients are obtained by solving coupled-perturbed equations within the approximative density-functional tight-binding method. The new computational scheme was implemented in a combination of Gromacs and Plumed. As a prospective application, proton-coupled electron transfer in a model molecular system is studied. Two collective variables are introduced naturally, one for the proton transfer and the other for the electron transfer. The results are in qualitative agreement with the extended free simulations performed for reference. Free energy minima as well as the mechanism of the process are identified correctly, while the topology of the transition region and the height of the energy barrier are only reproduced qualitatively. The application also illustrates possible difficulties with the new methodology. These may be inefficient sampling of spatial coordinates when atomic charges are biased exclusively and a decreased stability of the simulations. Still, the new approach represents a viable alternative for free energy calculations of a certain class of chemical reactions, for instance a proton-coupled electron transfer in proteins.
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Affiliation(s)
- Natacha Gillet
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
| | - Marcus Elstner
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
| | - Tomáš Kubař
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
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18
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Calcium, conformational selection, and redox-active tyrosine YZ in the photosynthetic oxygen-evolving cluster. Proc Natl Acad Sci U S A 2018; 115:5658-5663. [PMID: 29752381 DOI: 10.1073/pnas.1800758115] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In Photosystem II (PSII), YZ (Tyr161D1) participates in radical transfer between the chlorophyll donor and the Mn4CaO5 cluster. Under flashing illumination, the metal cluster cycles among five Sn states, and oxygen is evolved from water. The essential YZ is transiently oxidized and reduced on each flash in a proton-coupled electron transfer (PCET) reaction. Calcium is required for function. Of reconstituted divalent ions, only strontium restores oxygen evolution. YZ is predicted to hydrogen bond to calcium-bound water and to His190D1 in PSII structures. Here, we report a vibrational spectroscopic study of YZ radical and singlet in the presence of the metal cluster. The S2 state is trapped by illumination at 190 K; flash illumination then generates the S2YZ radical. Using reaction-induced FTIR spectroscopy and divalent ion depletion/substitution, we identify calcium-sensitive tyrosyl radical and tyrosine singlet bands in the S2 state. In calcium-containing PSII, two CO stretching bands are detected at 1,503 and 1,478 cm-1 These bands are assigned to two different radical conformers in calcium-containing PSII. At pH 6.0, the 1,503-cm-1 band shifts to 1,507 cm-1 in strontium-containing PSII, and the band is reduced in intensity in calcium-depleted PSII. These effects are consistent with a hydrogen-bonding interaction between the calcium site and one conformer of radical YZ. Analysis of the amide I region indicates that calcium selects for a PCET reaction in a subset of the YZ conformers, which are trapped in the S2 state. These results support the interpretation that YZ undergoes a redox-coupled conformational change, which is calcium dependent.
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19
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Liu J, Zhang J, Xu F, Lin Z, Li Z, Liu H. Structural characterizations of human periostin dimerization and cysteinylation. FEBS Lett 2018; 592:1789-1803. [PMID: 29754429 DOI: 10.1002/1873-3468.13091] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 04/20/2018] [Accepted: 05/02/2018] [Indexed: 01/20/2023]
Abstract
Human periostin plays a multifaceted role in remodeling the extracellular matrix milieu by interacting with other proteins and itself in both a heterophilic and homophilic manner. However, the structural mechanism for its extensive interactions has remained elusive. Here, we report the crystal structures of human periostin (EMI-Fas1I-IV ) and its Cys60Ala mutant. In combination with multi-angle light-scattering analysis and biochemical assays, the crystal structures reveal that periostin mainly exists as a dimer in solution and its homophilic interaction is mainly mediated by the EMI domain. Furthermore, Cys60 undergoes cysteinylation as confirmed by mass spectroscopy, and this site hardly affects the homophilic interaction. Also, the structures yield insights into how periostin forms heterophilic interactions with other proteins under physiological or pathological conditions.
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Affiliation(s)
- Jianmei Liu
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University Health Science Center, Haidian District, Beijing, China.,Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Haidian District, Beijing, China
| | - Junying Zhang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University Health Science Center, Haidian District, Beijing, China.,Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Haidian District, Beijing, China
| | - Fei Xu
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University Health Science Center, Haidian District, Beijing, China.,Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Haidian District, Beijing, China
| | - Zhaohan Lin
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University Health Science Center, Haidian District, Beijing, China.,Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Haidian District, Beijing, China
| | - Zhiqiang Li
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University Health Science Center, Haidian District, Beijing, China.,Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Haidian District, Beijing, China
| | - Heli Liu
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University Health Science Center, Haidian District, Beijing, China.,Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Haidian District, Beijing, China
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20
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Pieri E, Ledentu V, Huix-Rotllant M, Ferré N. Sampling the protonation states: the pH-dependent UV absorption spectrum of a polypeptide dyad. Phys Chem Chem Phys 2018; 20:23252-23261. [DOI: 10.1039/c8cp03557a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
When a chromophore interacts with several titratable molecular sites, the modeling of its photophysical properties requires to take into account all their probable protonation states.
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21
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Geng J, Aioub M, El-Sayed MA, Barry BA. An Ultraviolet Resonance Raman Spectroscopic Study of Cisplatin and Transplatin Interactions with Genomic DNA. J Phys Chem B 2017; 121:8975-8983. [PMID: 28925698 DOI: 10.1021/acs.jpcb.7b08156] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ultraviolet resonance Raman (UVRR) spectroscopy is a label-free method to define biomacromolecular interactions with anticancer compounds. Using UVRR, we describe the binding interactions of two Pt(II) compounds, cisplatin (cis-diamminedichloroplatinum(II)) and its isomer, transplatin, with nucleotides and genomic DNA. Cisplatin binds to DNA and other cellular components and triggers apoptosis, whereas transplatin is clinically ineffective. Here, a 244 nm UVRR study shows that purine UVRR bands are altered in frequency and intensity when mononucleotides are treated with cisplatin. This result is consistent with previous suggestions that purine N7 provides the cisplatin-binding site. The addition of cisplatin to DNA also causes changes in the UVRR spectrum, consistent with binding of platinum to purine N7 and disruption of hydrogen-bonding interactions between base pairs. Equally important is that transplatin treatment of DNA generates similar UVRR spectral changes, when compared to cisplatin-treated samples. Kinetic analysis, performed by monitoring decreases of the 1492 cm-1 band, reveals biphasic kinetics and is consistent with a two-step binding mechanism for both platinum compounds. For cisplatin-DNA, the rate constants (6.8 × 10-5 and 6.5 × 10-6 s-1) are assigned to the formation of monofunctional adducts and to bifunctional, intrastrand cross-linking, respectively. In transplatin-DNA, there is a 3.4-fold decrease in the rate constant of the slow phase, compared with the cisplatin samples. This change is attributed to generation of interstrand, rather than intrastrand, adducts. This longer reaction time may result in increased competition in the cellular environment and account, at least in part, for the lower pharmacological efficacy of transplatin.
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Affiliation(s)
- Jiafeng Geng
- School of Chemistry and Biochemistry, ‡Parker H. Petit Institute of Bioengineering and Bioscience, and §Laser Dynamics Laboratory, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Mena Aioub
- School of Chemistry and Biochemistry, ‡Parker H. Petit Institute of Bioengineering and Bioscience, and §Laser Dynamics Laboratory, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Mostafa A El-Sayed
- School of Chemistry and Biochemistry, ‡Parker H. Petit Institute of Bioengineering and Bioscience, and §Laser Dynamics Laboratory, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Bridgette A Barry
- School of Chemistry and Biochemistry, ‡Parker H. Petit Institute of Bioengineering and Bioscience, and §Laser Dynamics Laboratory, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
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22
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Hwang H, McCaslin TG, Hazel A, Pagba CV, Nevin CM, Pavlova A, Barry BA, Gumbart JC. Redox-Driven Conformational Dynamics in a Photosystem-II-Inspired β-Hairpin Maquette Determined through Spectroscopy and Simulation. J Phys Chem B 2017; 121:3536-3545. [DOI: 10.1021/acs.jpcb.6b09481] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Hyea Hwang
- School
of Materials Science and Engineering, ‡School of Chemistry and Biochemistry, §Petit Institute for
Bioengineering and Biosciences, and ∥School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Tyler G. McCaslin
- School
of Materials Science and Engineering, ‡School of Chemistry and Biochemistry, §Petit Institute for
Bioengineering and Biosciences, and ∥School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Anthony Hazel
- School
of Materials Science and Engineering, ‡School of Chemistry and Biochemistry, §Petit Institute for
Bioengineering and Biosciences, and ∥School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Cynthia V. Pagba
- School
of Materials Science and Engineering, ‡School of Chemistry and Biochemistry, §Petit Institute for
Bioengineering and Biosciences, and ∥School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Christina M. Nevin
- School
of Materials Science and Engineering, ‡School of Chemistry and Biochemistry, §Petit Institute for
Bioengineering and Biosciences, and ∥School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Anna Pavlova
- School
of Materials Science and Engineering, ‡School of Chemistry and Biochemistry, §Petit Institute for
Bioengineering and Biosciences, and ∥School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Bridgette A. Barry
- School
of Materials Science and Engineering, ‡School of Chemistry and Biochemistry, §Petit Institute for
Bioengineering and Biosciences, and ∥School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - James C. Gumbart
- School
of Materials Science and Engineering, ‡School of Chemistry and Biochemistry, §Petit Institute for
Bioengineering and Biosciences, and ∥School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
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23
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Bradley JM, Svistunenko DA, Moore GR, Le Brun NE. Tyr25, Tyr58 and Trp133 ofEscherichia colibacterioferritin transfer electrons between iron in the central cavity and the ferroxidase centre. Metallomics 2017; 9:1421-1428. [DOI: 10.1039/c7mt00187h] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Tyr58 and Trp133 play key roles in the formation and decay of the Tyr25 radical species ofE. coliBFR.
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Affiliation(s)
- Justin M. Bradley
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich Research Park
- Norwich
| | | | - Geoffrey R. Moore
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich Research Park
- Norwich
| | - Nick E. Le Brun
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich Research Park
- Norwich
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24
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Pagba CV, McCaslin TG, Chi SH, Perry JW, Barry BA. Proton-Coupled Electron Transfer and a Tyrosine-Histidine Pair in a Photosystem II-Inspired β-Hairpin Maquette: Kinetics on the Picosecond Time Scale. J Phys Chem B 2016; 120:1259-72. [PMID: 26886811 DOI: 10.1021/acs.jpcb.6b00560] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photosystem II (PSII) and ribonucleotide reductase employ oxidation and reduction of the tyrosine aromatic ring in radical transport pathways. Tyrosine-based reactions involve either proton-coupled electron transfer (PCET) or electron transfer (ET) alone, depending on the pH and the pKa of tyrosine's phenolic oxygen. In PSII, a subset of the PCET reactions are mediated by a tyrosine-histidine redox-driven proton relay, YD-His189. Peptide A is a PSII-inspired β-hairpin, which contains a single tyrosine (Y5) and histidine (H14). Previous electrochemical characterization indicated that Peptide A conducts a net PCET reaction between Y5 and H14, which have a cross-strand π-π interaction. The kinetic impact of H14 has not yet been explored. Here, we address this question through time-resolved absorption spectroscopy and 280-nm photolysis, which generates a neutral tyrosyl radical. The formation and decay of the neutral tyrosyl radical at 410 nm were monitored in Peptide A and its variant, Peptide C, in which H14 is replaced by cyclohexylalanine (Cha14). Significantly, both electron transfer (ET, pL 11, L = lyonium) and PCET (pL 9) were accelerated in Peptide A and C, compared to model tyrosinate or tyrosine at the same pL. Increased electronic coupling, mediated by the peptide backbone, can account for this rate acceleration. Deuterium exchange gave no significant solvent isotope effect in the peptides. At pL 9, but not at pL 11, the reaction rate decreased when H14 was mutated to Cha14. This decrease in rate is attributed to an increase in reorganization energy in the Cha14 mutant. The Y5-H14 mechanism in Peptide A is reminiscent of proton- and electron-transfer events involving YD-H189 in PSII. These results document a mechanism by which proton donors and acceptors can regulate the rate of PCET reactions.
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Affiliation(s)
- Cynthia V Pagba
- School of Chemistry and Biochemistry, the Petit Institute for Bioengineering and Bioscience, and the ‡Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Tyler G McCaslin
- School of Chemistry and Biochemistry, the Petit Institute for Bioengineering and Bioscience, and the ‡Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - San-Hui Chi
- School of Chemistry and Biochemistry, the Petit Institute for Bioengineering and Bioscience, and the ‡Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Joseph W Perry
- School of Chemistry and Biochemistry, the Petit Institute for Bioengineering and Bioscience, and the ‡Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Bridgette A Barry
- School of Chemistry and Biochemistry, the Petit Institute for Bioengineering and Bioscience, and the ‡Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
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