@article{ZengFrascaRumschoetteletal.2016,
  author    = {Zeng, Ting and Frasca, Stefano and Rumsch{\"o}ttel, Jens and Koetz, Joachim and Leimk{\"u}hler, Silke and Wollenberger, Ursula},
  title     = {Role of Conductive Nanoparticles in the Direct Unmediated Bioelectrocatalysis of Immobilized Sulfite Oxidase},
  series = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis},
  volume    = {28},
  journal   = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1040-0397},
  doi       = {10.1002/elan.201600246},
  pages     = {2303 -- 2310},
  year      = {2016},
  language  = {en}
}
@misc{YanFriemelAloisietal.2016,
  author    = {Yan, Robert and Friemel, Martin and Aloisi, Claudia and Huynen, Martijn and Taylor, Ian A. and Leimk{\"u}hler, Silke and Pastore, Annalisa},
  title     = {The eukaryotic-specific Isd11 is a complex- orphan protein with ability to bind the prokaryotic IscS},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {551},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-41190},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-411906},
  pages     = {14},
  year      = {2016},
  abstract  = {The eukaryotic protein Isd11 is a chaperone that binds and stabilizes the central component of the essential metabolic pathway responsible for formation of iron-sulfur clusters in mitochondria, the desulfurase Nfs1. Little is known about the exact role of Isd11. Here, we show that human Isd11 (ISD11) is a helical protein which exists in solution as an equilibrium between monomer, dimeric and tetrameric species when in the absence of human Nfs1 (NFS1). We also show that, surprisingly, recombinant ISD11 expressed in E. coli co-purifies with the bacterial orthologue of NFS1, IscS. Binding is weak but specific suggesting that, despite the absence of Isd11 sequences in bacteria, there is enough conservation between the two desulfurases to retain a similar mode of interaction. This knowledge may inform us on the conservation of the mode of binding of Isd11 to the desulfurase. We used evolutionary evidence to suggest Isd11 residues involved in the interaction.},
  language  = {en}
}
@article{YanFriemelAloisietal.2016,
  author    = {Yan, Robert and Friemel, Martin and Aloisi, Claudia and Huynen, Martijn and Taylor, Ian A. and Leimk{\"u}hler, Silke and Pastore, Annalisa},
  title     = {The Eukaryotic-Specific ISD11 Is a Complex-Orphan Protein with Ability to Bind the Prokaryotic IscS},
  series = {PLoS one},
  volume    = {11},
  journal   = {PLoS one},
  publisher = {PLoS},
  address   = {San Fransisco},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0157895},
  pages     = {383 -- 395},
  year      = {2016},
  abstract  = {The eukaryotic protein Isd11 is a chaperone that binds and stabilizes the central component of the essential metabolic pathway responsible for formation of iron-sulfur clusters in mitochondria, the desulfurase Nfs1. Little is known about the exact role of Isd11. Here, we show that human Isd11 (ISD11) is a helical protein which exists in solution as an equilibrium between monomer, dimeric and tetrameric species when in the absence of human Nfs1 (NFS1). We also show that, surprisingly, recombinant ISD11 expressed in E. coli co-purifies with the bacterial orthologue of NFS1, IscS. Binding is weak but specific suggesting that, despite the absence of Isd11 sequences in bacteria, there is enough conservation between the two desulfurases to retain a similar mode of interaction. This knowledge may inform us on the conservation of the mode of binding of Isd11 to the desulfurase. We used evolutionary evidence to suggest Isd11 residues involved in the interaction.},
  language  = {en}
}
@misc{TeraoRomaoLeimkuehleretal.2016,
  author    = {Terao, Mineko and Romao, Maria Joao and Leimk{\"u}hler, Silke and Bolis, Marco and Fratelli, Maddalena and Coelho, Catarina and Santos-Silva, Teresa and Garattini, Enrico},
  title     = {Structure and function of mammalian aldehyde oxidases},
  series = {Archives of toxicology : official journal of EUROTOX},
  volume    = {90},
  journal   = {Archives of toxicology : official journal of EUROTOX},
  publisher = {Springer},
  address   = {Heidelberg},
  issn      = {0340-5761},
  doi       = {10.1007/s00204-016-1683-1},
  pages     = {753 -- 780},
  year      = {2016},
  abstract  = {Mammalian aldehyde oxidases (AOXs; EC1.2.3.1) are a group of conserved proteins belonging to the family of molybdo-flavoenzymes along with the structurally related xanthine dehydrogenase enzyme. AOXs are characterized by broad substrate specificity, oxidizing not only aromatic and aliphatic aldehydes into the corresponding carboxylic acids, but also hydroxylating a series of heteroaromatic rings. The number of AOX isoenzymes expressed in different vertebrate species is variable. The two extremes are represented by humans, which express a single enzyme (AOX1) in many organs and mice or rats which are characterized by tissue-specific expression of four isoforms (AOX1, AOX2, AOX3, and AOX4). In vertebrates each AOX isoenzyme is the product of a distinct gene consisting of 35 highly conserved exons. The extant species-specific complement of AOX isoenzymes is the result of a complex evolutionary process consisting of a first phase characterized by a series of asynchronous gene duplications and a second phase where the pseudogenization and gene deletion events prevail. In the last few years remarkable advances in the elucidation of the structural characteristics and the catalytic mechanisms of mammalian AOXs have been made thanks to the successful crystallization of human AOX1 and mouse AOX3. Much less is known about the physiological function and physiological substrates of human AOX1 and other mammalian AOX isoenzymes, although the importance of these proteins in xenobiotic metabolism is fairly well established and their relevance in drug development is increasing. This review article provides an overview and a discussion of the current knowledge on mammalian AOX.},
  language  = {en}
}
@article{SarauliBorowskiPetersetal.2016,
  author    = {Sarauli, David and Borowski, Anja and Peters, Kristina and Schulz, Burkhard and Fattakhova-Rohlfing, Dina and Leimk{\"u}hler, Silke and Lisdat, Fred},
  title     = {Investigation of the pH-Dependent Impact of Sulfonated Polyaniline on Bioelectrocatalytic Activity of Xanthine Dehydrogenase},
  series = {ACS catalysis},
  volume    = {6},
  journal   = {ACS catalysis},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {2155-5435},
  doi       = {10.1021/acscatal.6b02011},
  pages     = {7152 -- 7159},
  year      = {2016},
  abstract  = {We report on the pH-dependent bioelectrocatalytic activity of the redox enzyme xanthine dehydrogenase (XDH) in the presence of sulfonated polyaniline PMSA1 (poly(2-methoxyaniline-5-sulfonic acid)-co-aniline). Ultraviolet-visible (UV-vis) spectroscopic measurements with both components in solution reveal electron transfer from the hypoxanthine (HX)-reduced enzyme to the polymer. The enzyme shows bioelectrocatalytic activity on indium tin oxide (ITO) electrodes, when the polymer is present. Depending on solution pH, different processes can be identified. It can be demonstrated that not only product-based communication with the electrode but also efficient polymer-supported bioelectrocatalysis occur. Interestingly, substrate dependent catalytic currents can be obtained in acidic and neutral solutions, although the highest activity of XDH with natural reaction partners is in the alkaline region. Furthermore, operation of the enzyme electrode without addition of the natural cofactor of XDH is feasible. Finally, macroporous ITO electrodes have been used as an immobilization platform for the fabrication of HX-sensitive electrodes. The study shows that the efficient polymer/enzyme interaction can be advantageously combined with the open structure of an electrode material of controlled pore size, resulting in good processability, stability, and defined signal transfer in the presence of a substrate.},
  language  = {en}
}
@article{PinyouRuffPoelleretal.2016,
  author    = {Pinyou, Piyanut and Ruff, Adrian and Poeller, Sascha and Alsaoub, Sabine and Leimk{\"u}hler, Silke and Wollenberger, Ursula and Schuhmann, Wolfgang},
  title     = {Wiring of the aldehyde oxidoreductase PaoABC to electrode surfaces via entrapment in low potential phenothiazine-modified redox polymers},
  series = {Bioelectrochemistry : an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry ; official journal of the Bioelectrochemical Society},
  volume    = {109},
  journal   = {Bioelectrochemistry : an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry ; official journal of the Bioelectrochemical Society},
  publisher = {Elsevier},
  address   = {Lausanne},
  issn      = {1567-5394},
  doi       = {10.1016/j.bioelechem.2015.12.005},
  pages     = {24 -- 30},
  year      = {2016},
  abstract  = {Phenothiazine-modified redox hydrogels were synthesized and used for the wiring of the aldehyde oxidoreductase PaoABC to electrode surfaces. The effects of the pH value and electrode surface modification on the biocatalytic activity of the layers were studied in the presence of vanillin as the substrate. The enzyme electrodes were successfully employed as bioanodes in vanillin/O-2 biofuel cells in combination with a high potential bilirubin oxidase biocathode. Open circuit voltages of around 700 mV could be obtained in a two compartment biofuel cell setup. Moreover, the use of a rather hydrophobic polymer with a high degree of crosslinking sites ensures the formation of stable polymer/enzyme films which were successfully used as bioanode in membrane-less biofuel cells. (C) 2015 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@misc{LeimkuehlerIobbiNivol2016,
  author    = {Leimk{\"u}hler, Silke and Iobbi-Nivol, Chantal},
  title     = {Bacterial molybdoenzymes: old enzymes for new purposes},
  series = {FEMS microbiology reviews},
  volume    = {40},
  journal   = {FEMS microbiology reviews},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0168-6445},
  doi       = {10.1093/femsre/fuv043},
  pages     = {1 -- 18},
  year      = {2016},
  abstract  = {Molybdoenzymes are widespread in eukaryotic and prokaryotic organisms where they play crucial functions in detoxification reactions in the metabolism of humans and bacteria, in nitrate assimilation in plants and in anaerobic respiration in bacteria. To be fully active, these enzymes require complex molybdenum-containing cofactors, which are inserted into the apoenzymes after folding. For almost all the bacterial molybdoenzymes, molybdenum cofactor insertion requires the involvement of specific chaperones. In this review, an overview on the molybdenum cofactor biosynthetic pathway is given together with the role of specific chaperones dedicated for molybdenum cofactor insertion and maturation. Many bacteria are involved in geochemical cycles on earth and therefore have an environmental impact. The roles of molybdoenzymes in bioremediation and for environmental applications are presented.This review gives an overview of the diverse mechanisms leading to the insertion of the different forms of the molybdenum cofactor into the respective target enzymes and summarizes the roles of different molybdoenzymes in the environment.This review gives an overview of the diverse mechanisms leading to the insertion of the different forms of the molybdenum cofactor into the respective target enzymes and summarizes the roles of different molybdoenzymes in the environment.},
  language  = {en}
}
@article{HartmannSchrapersUteschetal.2016,
  author    = {Hartmann, Tobias and Schrapers, Peer and Utesch, Tillmann and Nimtz, Manfred and Rippers, Yvonne and Dau, Holger and Mroginski, Maria Andrea and Haumann, Michael and Leimk{\"u}hler, Silke},
  title     = {The Molybdenum Active Site of Formate Dehydrogenase Is Capable of Catalyzing C-H Bond Cleavage and Oxygen Atom Transfer Reactions},
  series = {Biochemistry},
  volume    = {55},
  journal   = {Biochemistry},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0006-2960},
  doi       = {10.1021/acs.biochem.6b00002},
  pages     = {2381 -- 2389},
  year      = {2016},
  abstract  = {Formate dehydrogenases (FDHs) are capable of performing the reversible oxidation of formate and are enzymes of great interest for fuel cell applications and for the production of reduced carbon compounds as energy sources from CO2. Metal containing FDHs in general contain a highly conserved active site, comprising a molybdenum (or tungsten) center coordinated by two molybdopterin guanine dinucleotide molecules, a sulfido and a (seleno-)cysteine ligand, in addition to a histidine and arginine residue in the second coordination sphere. So far, the role of these amino acids in catalysis has not been studied in detail, because of the lack of suitable expression systems and the lability or oxygen sensitivity of the enzymes. Here, the roles of these active site residues is revealed using the Mo-containing FDH from Rhodobacter capsulatus. Our results show that the cysteine ligand at the Mo ion is displaced by the formate substrate during the reaction, the arginine has a direct role in substrate binding and stabilization, and the histidine elevates the pK(a) of the active site cysteine. We further found that in addition to reversible formate oxidation, the enzyme is further capable of reducing nitrate to nitrite. We propose a mechanistic scheme that combines both functionalities and provides important insights into the distinct mechanisms of C-H bond cleavage and oxygen atom transfer catalyzed by formate dehydrogenase.},
  language  = {en}
}
@article{HanLiOeneretal.2016,
  author    = {Han, Xiao Xia and Li, Junbo and {\"O}ner, Ibrahim Halil and Zhao, Bing and Leimk{\"u}hler, Silke and Hildebrandt, Peter and Weidinger, Inez M.},
  title     = {Nickel electrodes as a cheap and versatile platform for studying structure and function of immobilized redox proteins},
  series = {Analytica chimica acta : an international journal devoted to all branches of analytical chemistry},
  volume    = {941},
  journal   = {Analytica chimica acta : an international journal devoted to all branches of analytical chemistry},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0003-2670},
  doi       = {10.1016/j.aca.2016.08.053},
  pages     = {35 -- 40},
  year      = {2016},
  abstract  = {Practical use of many bioelectronic and bioanalytical devices is limited by the need of expensive materials and time consuming fabrication. Here we demonstrate the use of nickel electrodes as a simple and cheap solid support material for bioelectronic applications. The naturally nanostructured electrodes showed a surprisingly high electromagnetic surface enhancement upon light illumination such that immobilization and electron transfer reactions of the model redox proteins cytochrome b(5) (Cyt b(5)) and cytochrome c (Cyt c) could be followed via surface enhanced resonance Raman spectroscopy. It could be shown that the nickel surface, when used as received, promotes a very efficient binding of the proteins upon preservation of their native structure. The immobilized redox proteins could efficiently exchange electrons with the electrode and could even act as an electron relay between the electrode and solubilized myoglobin. Our results open up new possibility for nickel electrodes as an exceptional good support for bioelectronic devices and biosensors on the one hand and for surface enhanced spectroscopic investigations on the other hand. (C) 2016 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@article{FotiHartmannCoelhoetal.2016,
  author    = {Foti, Alessandro and Hartmann, Tobias and Coelho, Catarina and Santos-Silva, Teresa and Romao, Maria Joao and Leimk{\"u}hler, Silke},
  title     = {Optimization of the Expression of Human Aldehyde Oxidase for Investigations of Single-Nucleotide Polymorphisms},
  series = {Drug metabolism and disposition : the biological fate of chemicals},
  volume    = {44},
  journal   = {Drug metabolism and disposition : the biological fate of chemicals},
  publisher = {American Society for Pharmacology and Experimental Therapeutics},
  address   = {Bethesda},
  issn      = {0090-9556},
  doi       = {10.1124/dmd.115.068395},
  pages     = {1277 -- 1285},
  year      = {2016},
  abstract  = {Aldehyde oxidase (AOX1) is an enzyme with broad substrate specificity, catalyzing the oxidation of a wide range of endogenous and exogenous aldehydes as well as N-heterocyclic aromatic compounds. In humans, the enzyme's role in phase I drug metabolism has been established and its importance is now emerging. However, the true physiologic function of AOX1 in mammals is still unknown. Further, numerous single-nucleotide polymorphisms (SNPs) have been identified in human AOX1. SNPs are a major source of interindividual variability in the human population, and SNP-based amino acid exchanges in AOX1 reportedly modulate the catalytic function of the enzyme in either a positive or negative fashion. For the reliable analysis of the effect of amino acid exchanges in human proteins, the existence of reproducible expression systems for the production of active protein in ample amounts for kinetic, spectroscopic, and crystallographic studies is required. In our study we report an optimized expression system for hAOX1 in Escherichia coli using a codon-optimized construct. The codon-optimization resulted in an up to 15-fold increase of protein production and a simplified purification procedure. The optimized expression system was used to study three SNPs that result in amino acid changes C44W, G1269R, and S1271L. In addition, the crystal structure of the S1271L SNP was solved. We demonstrate that the recombinant enzyme can be used for future studies to exploit the role of AOX in drug metabolism, and for the identification and synthesis of new drugs targeting AOX when combined with crystallographic and modeling studies.},
  language  = {en}
}