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Scientific Reports Feb 2020Hydrogen has the potential to play an important role in decarbonising our energy systems. Crucial to achieving this is the ability to produce clean sources of hydrogen...
Hydrogen has the potential to play an important role in decarbonising our energy systems. Crucial to achieving this is the ability to produce clean sources of hydrogen using renewable energy sources. Currently platinum is commonly used as a hydrogen evolution catalyst, however, the scarcity and expense of platinum is driving the need to develop non-platinum-based catalysts. Here we report a protein-based hydrogen evolution catalyst based on a recombinant silk protein from honeybees and a metal macrocycle, cobalt protoporphyrin (CoPPIX). We enhanced the hydrogen evolution activity three fold compared to the unmodified silk protein by varying the coordinating ligands to the metal centre. Finally, to demonstrate the use of our biological catalyst, we built a proton exchange membrane (PEM) water electrolysis cell using CoPPIX-silk as the hydrogen evolution catalyst that is able to produce hydrogen with a 98% Faradaic efficiency. This represents an exciting advance towards allowing protein-based catalysts to be used in electrolysis cells.
Topics: Animals; Bees; Catalysis; Hydrogen; Insect Proteins; Metalloproteins; Protein Engineering; Protoporphyrins; Recombinant Proteins; Silk
PubMed: 32111964
DOI: 10.1038/s41598-020-60730-y -
Journal of Inorganic Biochemistry Oct 2022Engineering non-native metal active sites into proteins using canonical amino acids offers many advantages but is hampered by significant challenges. The TIM barrel...
Engineering non-native metal active sites into proteins using canonical amino acids offers many advantages but is hampered by significant challenges. The TIM barrel protein, imidazole glycerol phosphate synthase from the hyperthermophilic organism Thermotoga maritima (tHisF), is well-suited for the construction of artificial metalloenzymes by this approach. To this end, we have generated a tHisF variant (tHisF) with a Glu/His/His motif for metal ion coordination. Crystal structures of Zn:tHisF and Ni:tHisF reveal that both metal ions bind to the engineered histidines. However, the two metals bind at distinct sites with different geometries, demonstrating the adaptability of tHisF. Only Zn additionally ligates the Glu residue and adopts a tetrahedral geometry. The pseudo-octahedral Ni site comprises the two His and a native Ser residue. Ni:tHisF catalyzes the oxidative cleavage of the flavanols quercetin and myricetin, providing an unprecedented example of an artificial metalloprotein with quercetinase activity.
Topics: Binding Sites; Dioxygenases; Metalloproteins; Metals; Nickel
PubMed: 35841720
DOI: 10.1016/j.jinorgbio.2022.111914 -
Biochemical Society Transactions Feb 2018The single-molecule properties of metalloproteins have provided an intensely active research area in recent years. This brief review covers some of the techniques used... (Review)
Review
The single-molecule properties of metalloproteins have provided an intensely active research area in recent years. This brief review covers some of the techniques used to prepare, measure and analyse the electron transfer properties of metalloproteins, concentrating on scanning tunnelling microscopy-based techniques and advances in attachment of proteins to electrodes.
Topics: Electrodes; Electron Transport; Metalloproteins; Microscopy, Scanning Tunneling; Molecular Probes; Single Molecule Imaging
PubMed: 29273619
DOI: 10.1042/BST20170229 -
Current Opinion in Structural Biology Aug 2018The ability to rationally design metalloproteins with desired functions remains a difficult challenge despite many years of effort. Recently, the potential of using... (Review)
Review
The ability to rationally design metalloproteins with desired functions remains a difficult challenge despite many years of effort. Recently, the potential of using genetically encoded metal-chelating non-canonical amino acids (NCAAs) to circumvent longstanding difficulties in this field has begun to be explored. In this review, we describe the development of this approach and its application to the rational design or directed evolution of NCAA-containing metalloproteins in which the bound metal ions serve in structural roles, as catalysts, or as regulators of the assembly or disassembly of protein complexes. These successes highlight the fact that amino acids not found in nature can recapitulate the functions of their naturally occurring counterparts and suggest the promise of this nascent approach for simplifying the metalloprotein design problem.
Topics: Amino Acids; Chelating Agents; Metalloendopeptidases; Metalloproteins; Metals; Models, Molecular; Molecular Conformation; Protein Binding; Protein Engineering; Structure-Activity Relationship
PubMed: 29980106
DOI: 10.1016/j.sbi.2018.06.001 -
Chemphyschem : a European Journal of... Jul 2013We have briefly overviewed recent efforts in the electrochemistry of single transition metal complex, redox metalloprotein, and redox-marked oligonucleotide (ON)... (Review)
Review
We have briefly overviewed recent efforts in the electrochemistry of single transition metal complex, redox metalloprotein, and redox-marked oligonucleotide (ON) molecules. We have particularly studied self-assembled molecular monolayers (SAMs) of several 5'-C6-SH single- (ss) and double-strand (ds) ONs immobilized on Au(111) electrode surfaces via Au-S bond formation, using a combination of nucleic acid chemistry, electrochemistry and electrochemically controlled scanning tunnelling microscopy (in situ STM). Ds ONs stabilized by multiply charged cations and locked nucleic acid (LNA) monomers have been primary targets, with a view on stabilizing the ds-ONs and improving voltammetric signals of intercalating electrochemical redox probes. Voltammetric signals of the intercalator anthraquinone monosulfonate (AQMS) at ds-DNA/Au(111) surfaces diluted by mercaptohexanol are significantly sharpened and more robust in the presence than in the absence of [Co(NH3)6](3+). AQMS also displays robust Faradaic voltammetric signals specific to the ds form on binding to similar LNA/Au(111) surfaces, but this signal only evolves after successive voltammetric scanning into negative potential ranges. Triply charged spermidine (Spd) invokes itself a strong voltammetric signal, which is specific to the ds form and fully matched sequences. This signal is of non-Faradaic, capacitive origin but appears in the same potential range as the Faradaic AQMS signal. In situ STM shows that molecular scale structures of the size of Spd-stabilized ds-ONs are densely packed over the Au(111) surface in potential ranges around the capacitive peak potential.
Topics: DNA; Electrochemical Techniques; Electrodes; Gold; Metalloproteins; Particle Size; Surface Properties
PubMed: 23788363
DOI: 10.1002/cphc.201300299 -
Dalton Transactions (Cambridge, England... Apr 2011Numerous metalloproteins are important therapeutic targets that are gaining increased attention in the medicinal and bioinorganic chemistry communities. This Perspective... (Review)
Review
Numerous metalloproteins are important therapeutic targets that are gaining increased attention in the medicinal and bioinorganic chemistry communities. This Perspective article describes some emerging trends and recent findings in the area of metalloprotein inhibitor discovery and development. In particular, increasing recognition of the importance of the metal-ligand interactions in these systems calls for more input and consideration from the bioinorganic community to address questions traditionally confined to the medicinal chemistry community.
Topics: Aldose-Ketose Isomerases; Aminopeptidases; Animals; Drug Discovery; Enzyme Inhibitors; Humans; Metalloproteins; Methionyl Aminopeptidases; Multienzyme Complexes; Oxidoreductases; Prodrugs
PubMed: 21290034
DOI: 10.1039/c0dt01743d -
Current Topics in Medicinal Chemistry 2016
Topics: Humans; Metalloproteins; Protease Inhibitors; Small Molecule Libraries; Structure-Activity Relationship
PubMed: 26281912
DOI: 10.2174/1568026615999150818120217 -
BioEssays : News and Reviews in... Jul 1996In many cells, a nitric oxide (NO) synthase inducible by immunological stimuli produces a sustained flow of NO that lasts a long time. NO is a short-lived molecule but... (Review)
Review
In many cells, a nitric oxide (NO) synthase inducible by immunological stimuli produces a sustained flow of NO that lasts a long time. NO is a short-lived molecule but it is a diffusible ligand believed to be capable of reaching distal target sites. Further, several lines of evidence indicate that cysteine-rich motifs of metal-binding proteins, as well as redox-sensitive metal clusters of metalloproteins, are natural sensors of bioradicals like NO. In metalloregulatory proteins, metals are often conveniently located at binding sites and bound to cysteine residues. Accordingly, disruption of the metal-thiolate polymetallic clusters should trigger significant remodelling of the protein structure involved in regulation. We can therefore postulate that the nitrosation reaction occurring at metal centres or cysteine-rich motifs will preclude correct binding to regulatory sites. Several examples are given of metalloregulatory proteins whose metal is bound to thiols and may then become sensitive to NO. Recent observations indicate that in response to NO synthesis, iron regulatory protein, a eukaryotic bifunctional [Fe-S] protein, switches from acting as aconitase to being an RNA-binding regulator, and we suggest that the interplay between NO or a NO-derived molecule and metal clusters at critical allosteric sites may be a crucial component of the cellular response to environmental stress.
Topics: DNA-Binding Proteins; Iron; Iron-Regulatory Proteins; Iron-Sulfur Proteins; Metalloproteins; Models, Chemical; Nitric Oxide; Nitric Oxide Synthase; RNA-Binding Proteins
PubMed: 8757934
DOI: 10.1002/bies.950180706 -
Methods in Molecular Biology (Clifton,... 2019An overview of modern methods used in the preparation and characterization of molybdenum-containing enzymes is presented, with an emphasis on those methods that have...
An overview of modern methods used in the preparation and characterization of molybdenum-containing enzymes is presented, with an emphasis on those methods that have been developed over the past decade to address specific difficulties frequently encountered in studies of these enzymes.
Topics: Anaerobiosis; Metalloproteins; Molybdenum; Oxygen
PubMed: 30317474
DOI: 10.1007/978-1-4939-8864-8_4 -
Nature Chemistry Apr 2016Enzymes use binding energy to stabilize their substrates in high-energy states that are otherwise inaccessible at ambient temperature. Here we show that a de novo...
Enzymes use binding energy to stabilize their substrates in high-energy states that are otherwise inaccessible at ambient temperature. Here we show that a de novo designed Zn(II) metalloprotein stabilizes a chemically reactive organic radical that is otherwise unstable in aqueous media. The protein binds tightly to and stabilizes the radical semiquinone form of 3,5-di-tert-butylcatechol. Solution NMR spectroscopy in conjunction with molecular dynamics simulations show that the substrate binds in the active site pocket where it is stabilized by metal-ligand interactions as well as by burial of its hydrophobic groups. Spectrochemical redox titrations show that the protein stabilized the semiquinone by reducing the electrochemical midpoint potential for its formation via the one-electron oxidation of the catechol by approximately 400 mV (9 kcal mol(-1)). Therefore, the inherent chemical properties of the radical were changed drastically by harnessing its binding energy to the metalloprotein. This model sets the basis for designed enzymes with radical cofactors to tackle challenging chemistry.
Topics: Amino Acid Sequence; Benzoquinones; Magnetic Resonance Spectroscopy; Metalloproteins; Models, Theoretical; Molecular Dynamics Simulation; Molecular Sequence Data
PubMed: 27001731
DOI: 10.1038/nchem.2453