Nickel-iron-selenium hydrogenases - An overview

[NiFeSe] hydrogenases are a subgroup of the large family of [NiFe] hydrogenases in which a selenocysteine ligand coordinates the Ni atom at the active site. As observed for other selenoproteins, the [NiFeSe] hydrogenases display much higher catalytic activities than their Cys-containing homologues. Here, we review the biochemical, catalytic, spectroscopic and structural properties of known [NiFeSe] hydrogenases, namely from the Hys (group 1 [NiFeSe] hydrogenase), Fru (F420-reducing [NiFeSe] hydrogenases) and Vhu families (F420-non-reducing [NiFeSe] hydrogenases). A survey of new [NiFeSe] hydrogenases present in the databases showed that all enzymes belong to either group 1 periplasmic uptake hydrogenases (Hys) or to group 3 cytoplasmic hydrogenases (Fru and Vhu) and are present in either sulfate-re-ducing or methanogenic microorganisms. In both kinds of organisms, the [NiFeSe] hydrogenases are preferred over their Cys-containing homologues if selenium is available. Since no structural information is available for the Vhu and Fru enzymes, we have modelled the large subunit of these enzymes and analyzed the area surrounding the active site. Three [NiFeSe] hydrogenases of the Hys and Vhu types were identified in which the selenocysteine residue is found in a different location in the sequence, which could result in a different coordination to the Ni atom. The high activity and fast reactivation, together with a degree of oxygen tolerance for the H2-production activity, make the Hys hydrogenases attractive catalysts for technological applications. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA.This work was supported by research grants PTDC/BIAPRO/70429/2006 funded by Fundação para a Ciência e Tecnologia (FCT, MCES, Portugal) and European Union FEDER program, and CTQ2006-12097 funded by the Ministerio de Ciencia e Innovacion (Spain).Peer Reviewe

Laccase-modified gold nanorods for electrocatalytic reduction of oxygen

The multicopper oxidase Trametes hirsuta laccase (ThLc) served as a bioelectrocatalyst on nanostructured cathodes. Nanostructuring was provided by gold nanorods (AuNRs), which were characterized and covalently attached to electrodes made of low-density graphite. The nanostructured electrode was the scaffold for covalent and oriented attachment of ThLc. The bioelectrocatalytic currents measured for oxygen reductionwere as high as 0.5 mA/cm2 and 0.7 mA/cm2, which were recorded under direct and mediated electron transfer regimes, respectively. The experimental data were fitted to mathematical models showing that when the O2 is bioelectroreduced at high rotation speed of the electrode the heterogeneous electron transfer step is the rateliming stage. The electrochemical measurement hints a wider population of non-optimally wired laccases than previously reported for 5-8 nmsize Au nanoparticle-modified electrode, which could be due to a larger size of the AuNRs when compared to the laccases as well as their different crystal facets. © 2015 Elsevier B.V.This work was funded by the Seventh Framework Programme (BIOENERGY FP7-PEOPLE-2013-607793 project).Peer Reviewe

Electricity generation by microorganisms in the sediment-water interface of an extreme acidic microcosm

The attachment of microorganisms to electrodes is of great interest for electricity generation in microbial fuel cells (MFC) or other applications in bioelectrochemical systems (BES). In this work, a microcosm of the acidic ecosystem of Río Tinto was built and graphite electrodes were introduced at different points. This allowed the study of electricity generation in the sediment/water interface and the involvement of acidophilic microorganisms as biocatalysts of the anodic and cathodic reactions in a fuel-cell configuration. Current densities and power outputs of up to 3.5 A/m2 and 0.3 W/m2 , , respectively, were measured at pH 3. Microbial analyses of the electrode surfaces showed that Acidiphilium spp., which uses organic compounds as electron donors, were the predominant biocatalysts of the anodic reactions, whereas the aerobic iron oxidizers Acidithiobacillus ferrooxidans and Leptospirillum spp. were detected mainly on the cathode surface. [Int Microbiol 2011; 14(2):73-81]Peer reviewe

Lacasa de alto potencial redox funcional en sangre mediante evolución dirigida método de obtención y sus aplicaciones

La presente invención describe una lacasa de alto potencial redox obtenida mediante evolución molecular dirigida que es activa en condiciones electrofisiológicas, que resiste elevadas concentraciones de haluros, que tiene una actividad significativa a pHs neutros/alcalinos y que es activa en sangre y plasma humano. La presente invención se refiere a la secuencia aminoacídica de dicha lacasa, a la secuencia nucleotídica que codifica para dicha lacasa y células que permiten su obtención. La lacasa de la invención presenta aplicaciones en diversos sectores: nano-biotecnología, biomedicina, procesos de biorremediación, industria papelera y química fina.Peer reviewedConsejop Superior de Investigaciones CientíficasA1 Solicitud de patente con informe sobre el estado de la técnic

Lacasa de alto potencial redox funcional en sangre mediante evolución dirigida método de obtención y sus aplicaciones

La presente invención describe una lacasa de alto potencial redox obtenida mediante evolución molecular dirigida que es activa en condiciones electrofisiológicas, que resiste elevadas concentraciones de haluros, que tiene una actividad significativa a pHs neutros/alcalinos y que es activa en sangre y plasma humano. La presente invención se refiere a la secuencia aminoacídica de dicha lacasa, a la secuencia nucleotídica que codifica para dicha lacasa y células que permiten su obtención. La lacasa de la invención presenta aplicaciones en diversos sectores: nano-biotecnología, biomedicina, procesos de biorremediación, industria papelera y química fina.Peer reviewedConsejop Superior de Investigaciones CientíficasB1 Patente sin examen previ

Antioxidant and antimicrobial peptide fractions from squid and tuna skin gelatin

27 páginas, 4 figuras, 4 tablas.Gelatin extracted from tuna skins and giant squid tunics were hydrolysed with Alcalase at 50ºC for 3h. Two peptide fractions (1-10K and ≤1K) were obtained from each gelatin hydrolysate by subjecting them to centrifugal ultrafiltration using successively a 10 kDa and a 1 kDa membrane. The peptide fractions were characterized in terms of amino acid composition and Fourier transform infrared (FTIR) spectroscopy. Antioxidant properties were tested according to the Ferric Reducing Antioxidant Power (FRAP) assay and the radical scavenging capacity (ABTS) assay. A disk diffusion test was performed to test antimicrobial action against a panel of Gram-positive and Gramnegative pathogenic and fish spoilage-associated microorganisms. Although antioxidant and antimicrobial properties could be detected in all tested peptide fractions, the lowermost molecular weight fraction from squid hydrolysate presented the highest reducing and radical scavenging capacities, whereas microbial growth inhibition was found to be specifically related to the type of microorganism.This study was supported by the Spanish “Ministerio de Educación y Ciencia” (project AGL2005-02380/ALI and AGL2008-02135/ALI).Peer reviewe

Reconstitution of respiratory complex I on a biomimetic membrane supported on gold electrodes

For the first time, respiratory complex I has been reconstituted on an electrode preserving its structure and activity. Respiratory complex I is a membrane-bound enzyme that has an essential function in cellular energy production. It couples NADH:quinone oxidoreduction to translocation of ions across the cellular (in prokaryotes) or mitochondrial membranes. Therefore, complex I contributes to the establishment and maintenance of the transmembrane difference of electrochemical potential required for adenosine triphosphate synthesis, transport, and motility. Our new strategy has been applied for reconstituting the bacterial complex I from Rhodothermus marinus onto a biomimetic membrane supported on gold electrodes modified with a thiol self-assembled monolayer (SAM). Atomic force microscopy and faradaic impedance measurements give evidence of the biomimetic construction, whereas electrochemical measurements show its functionality. Both electron transfer and proton translocation by respiratory complex I were monitored, simulating in vivo conditions. © 2014 American Chemical Society.This work was funded by the Spanish MINECO (project CTQ2012-32448) and by Fundação para a Ciência e a Tecnologia (PTDC/BBB-BQB/2294/2012 to M.M.P.). The work was also supported by Fundação para a Ciência e a Tecnologia through grant # PEst-OE/EQB/LA0004/2011. M.P. and O.G.-S. acknowledge the Ramon y Cajal and the FPI programs respectively from the Spanish MINECO. A.P.B. is recipient of a grant from Fundação para a Ciência e a Tecnologia (SFRH/BPD/80741/2011).Peer Reviewe

Electro-enzymatic ATP regeneration coupled to biocatalytic phosphorylation reactions

Funding Information: A.L.D, M.P. and M.V. thank grants RTI2018-095090-B-I00 and PID2021-1241160B-I00 funded by MCIN/AEI/ 10.13039/501100011033 and by the European Union, and 2021AEP014 funded by CSIC. G.G.M. thanks grant BES-2016-078815 funded by MCIN/AEI/ 10.13039/501100011033 and by the European Union. I.L.-M. and M.V. acknowledge financial support through grant S2018/BAA-4403 SINOXPHOS-CM (EU-FEDER). I.A.C.P. and A.M.C. thank support from the Fundação para a Ciência e Tecnologia through fellowship SFRH/BD/146475/2019 and MOSTMICRO-ITQB R&D Unit (UIDB/04612/2020, UIDP/04612/2020) and LS4FUTURE Associated Laboratory (LA/P/0087/2020). Publisher Copyright: © 2023 The Author(s)Adenosine-5-triphosphate (ATP) is the main energy vector in biological systems, thus its regeneration is an important issue for the application of many enzymes of interest in biocatalysis and synthetic biology. We have developed an electroenzymatic ATP regeneration system consisting in a gold electrode modified with a floating phospholipid bilayer that allows coupling the catalytic activity of two membrane-bound enzymes: NiFeSe hydrogenase from Desulfovibrio vulgaris and F1Fo-ATP synthase from Escherichia coli. Thus, H2 is used as a fuel for producing ATP. This electro-enzymatic assembly is studied as ATP regeneration system of phosphorylation reactions catalysed by kinases, such as hexokinase and NAD+-kinase for respectively producing glucose-6-phosphate and NADP+.publishersversionpublishe

Combinatorial saturation mutagenesis of the Myceliophthora thermophila laccase T2 mutant: The connection between the C-terminal plug and the conserved509VSG511 tripeptide

A mutant laccase from the Ascomycete Myceliophthora thermophila has been submitted to iterative cycles of combinatorial saturation mutagenesis through in vivo overlap extension in Saccharomyces cerevisiae. Over 180,000 clones were explored, among which the S510G mutant revealed a direct interaction between the conserved 509VSG511 tripeptide, located in the neighborhood of the T1 site, and the C-terminal plug. The Km O 2 value of the mutant increased 1.5-fold, and the electron transfer pathway between the reducing substrate and the T1 copper ion was altered, improving the catalytic efficiency towards non-phenolic and phenolic substrates by about 3- and 8-fold. Although the geometry at the T1 site was perturbed by the mutation, paradoxically the laccase redox potential was not significantly altered. Together, the results obtained in this study suggest that the 509VSG511 tripeptide may play a hitherto unrecognized role in regulating the traffic of oxygen through the C-terminal plug, the latter blocking access to the T2/T3 copper cluster in the native enzyme.This research was funded by the Spanish Ministry of Education and Science projects VEM2004-08559, CTQ2005-08925-C02-02/PPQ and CTQ2006-12097/BQU; the EU project NMP2-CT-2006-026456; a CSIC project 200580M121, the Ramón y Cajal Program, and the Swedish Research Council (Vetenskapsårdet, project ärandenummer: 621-2005-3581). MZ was supported by a fellowship from the “Gobierno Vasco” and CV by a fellowship from the FPU program of the “Ministerio de Educación y Ciencia”.Peer Reviewe

The Origin of the Hubble Sequence in Lambda-CDM Cosmology

The Galform semi-analytic model of galaxy formation is used to explore the mechanisms primarily responsible for the three types of galaxies seen in the local universe: bulge, bulge+disk and disk, identified with the visual morphological types E, S0/a-Sbc, and Sc-Scd, respectively. With a suitable choice of parameters the Galform model can accurately reproduce the observed local K_s-band luminosity function (LF) for galaxies split by visual morphological type. The successful set of model parameters is used to populate the Millennium Simulation with 9.4 million galaxies and their dark matter halos. The resulting catalogue is then used to explore the evolution of galaxies through cosmic history. The model predictions concur with recent observational results including the galaxy merger rate, the star formation rate and the seemingly anti-hierarchical evolution of ellipticals. However, the model also predicts significant evolution of the elliptical galaxy LF that is not observed. The discrepancy raises the possibility that samples of z~1 galaxies which have been selected using colour and morphological criteria may be contaminated with galaxies that are not actually ellipticals.Comment: Accepted for publication in MNRAS. Missing reference adde