Hydrogen Peroxide in Biocatalysis. A Dangerous Liaison

Hydrogen peroxide is a substrate or side-product in many enzyme-catalyzed reactions. For example, it is a side-product of oxidases, resulting from the re-oxidation of FAD with molecular oxygen, and it is a substrate for peroxidases and other enzymes. However, hydrogen peroxide is able to chemically modify the peptide core of the enzymes it interacts with, and also to produce the oxidation of some cofactors and prostetic groups (e.g., the hemo group). Thus, the development of strategies that may permit to increase the stability of enzymes in the presence of this deleterious reagent is an interesting target. This enhancement in enzyme stability has been attempted following almost all available strategies: site-directed mutagenesis (eliminating the most reactive moieties), medium engineering (using stabilizers), immobilization and chemical modification (trying to generate hydrophobic environments surrounding the enzyme, to confer higher rigidity to the protein or to generate oxidation-resistant groups), or the use of systems capable of decomposing hydrogen peroxide under very mild conditions. If hydrogen peroxide is just a side-product, its immediate removal has been reported to be the best solution. In some cases, when hydrogen peroxide is the substrate and its decomposition is not a sensible solution, researchers coupled one enzyme generating hydrogen peroxide “in situ” to the target enzyme resulting in a continuous supply of this reagent at low concentrations thus preventing enzyme inactivation. This review will focus on the general role of hydrogen peroxide in biocatalysis, the main mechanisms of enzyme inactivation produced by this reactive and the different strategies used to prevent enzyme inactivation caused by this “dangerous liaison”.This work has been supported by grant CTQ2009-07568 from Spanish Ministerio de Ciencia e Innovación. A. Berenguer-Murcia thanks the Spanish Ministerio de Ciencia e Innovación for a Ramon y Cajal fellowship (RyC-2009-03813). Mr. Hernandez is a holder of a MAEC-AECID fellowship

- LA COMPRA IMPULSIVA Y LA COMPRA PATOLÓGICA: EL MODELO CAC#

In recent years there is a new trend researching impulsive and compulsive buying in consumption. Although there has been literature from 1940, this topic has been continuously misunderstood by the scientifics, mainly because their applied and business perspective. It is our effort to understand and formulate a new model, the structural and functional model CAC (Affective and Cognitive Buying) where we try to overcome the general assumptions drew by the consumer involvement conceptualization. Moreover, this model supposes an introduction to the emotional face of consumers coherently with new approaches that grow in consumer literature. En los últimos años ha aparecido una nueva tendencia de investigación relacionada con la compra compulsiva y la compra impulsiva. Aunque existe literatura desde los años 40, este tema ha sido continuamente entendido desde una perspectiva empresarial y aplicada que ha dificultado su estudio. En este trabajo pretendemos comprender y formular un nuevo modelo de consumo, el modelo CAC (Compra Afectivo-Cognitiva) donde intentamos superar las líneas generales que plantea la conceptualización de la implicación del consumidor. Más aún, este modelo supone una introducción a la cara emocional de los consumidores de modo coherente con las nuevas tendencias que están surgiendo en la literatura del consumidor.Compra impulsiva, compra compulsiva, compra adictiva, compra patológica. Impulse buying, compulsive buying, addictive buying, pathological buying.

Ficin: A protease extract with relevance in biotechnology and biocatalysis

Due to the problems raised by the use of animal or microbial recombinant proteases, the use of proteases from vegetable origin is becoming increasingly popular.. Among them, sulfidryl proteases have a special interest. Ficin is an outstanding example of this kind of proteases. This paper aims to be to make a comprehensive review of the recent uses of this enzyme, including for example protein hydrolysis, the production of bioactive peptides and antibodies fragments (researchers point that ficin results are more reproducible than using other proteases), meat tenderization, milk coagulations in cheese making or peptide synthesis. Efforts to get industrial immobilized biocatalysts of the enzyme will be also described. The review shows the huge potential and brilliant prospect that this enzyme can have in the near future.We gratefully recognize the support from the Ministerio de Ciencia e Innovación from Spanish Government (project number CTQ2017-86170-R). The FPU fellowship (Ministerio de Educacion) for Mr. Morellon–Sterling and the fellowship for Mr. Siar from the Algerian Ministry of Higher Education and Scientific Research are also thanked

Madeira-a tourist destination for asthma sufferers

Madeira Island is a famous tourist destination due to its natural and climatic values. Taking into account optimal weather conditions, flora richness and access to various substrates facilitating fungal growth, we hypothesised a very high risk of elevated fungal spore and pollen grain concentrations in the air of Funchal, the capital of Madeira. Concentration levels of the most allergenic taxa were measured from 2003 to 2009, using a 7-day volumetric air sampler, followed by microscopy analysis. Dependence of bioaerosols on the weather conditions and land use were assessed using spatial and statistical tools. Obtained results were re-visited by a comparison with hospital admission data recorded at the Dr. Nélio Mendonça Hospital in Funchal. Our results showed that despite propitious climatic conditions, overall pollen grain and fungal spore concentrations in the air were very low and did not exceed any clinically established threshold values. Pollen and spore peak concentrations also did not match with asthma outbreaks in the winter. Identification of places that are "free" from biological air pollution over the summer, such as Madeira Island, is very important from the allergic point of view.info:eu-repo/semantics/publishedVersio

Nanocatalysts for ethanol oxidation: Synthesis and characterisation

Carbon-supported binary PtSn/C and ternary PtSnNi/C catalysts were prepared for the electro-oxidation of ethanol. The carbon-supported nanoparticles were synthesised by employing a modified polyol methodology and characterised in terms of structure, morphology and composition by using XRD, EDX and TEM techniques. Their electrocatalytic behaviour for ethanol oxidation (EO) was investigated by employing a disccomposite electrode covered by a thin layer of catalyst imbedded in a Nafion polymer electrolyte film. An enhancement of the EO through a negative shift of the onset oxidation potential and higher current density at constant potentials were observed on the PtSnNi/C electrodes as compared to those for PtSn/C electrodes. The temperature was changed in the range 40 °C ≤ t ≤ 80 °C, and the variation of the activation energy calculated by linear regression of the Arrhenius plots.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Nanocatalysts for ethanol oxidation: Synthesis and characterisation

Carbon-supported binary PtSn/C and ternary PtSnNi/C catalysts were prepared for the electro-oxidation of ethanol. The carbon-supported nanoparticles were synthesised by employing a modified polyol methodology and characterised in terms of structure, morphology and composition by using XRD, EDX and TEM techniques. Their electrocatalytic behaviour for ethanol oxidation (EO) was investigated by employing a disccomposite electrode covered by a thin layer of catalyst imbedded in a Nafion polymer electrolyte film. An enhancement of the EO through a negative shift of the onset oxidation potential and higher current density at constant potentials were observed on the PtSnNi/C electrodes as compared to those for PtSn/C electrodes. The temperature was changed in the range 40 °C ≤ t ≤ 80 °C, and the variation of the activation energy calculated by linear regression of the Arrhenius plots.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Reconfigurable DPD based on ANNs for wideband load modulated balanced amplifiers under dynamic operation from 1.8 to 2.4 GHz

This article proposes a methodology to ensure linear amplification of a load modulated balanced amplifier (LMBA) while keeping the power efficiency as high as possible over a frequency band ranging from 1.8 to 2.4 GHz and where the transmitted signals can present different bandwidth (BW) configurations. The proposed reconfigurable linearization methodology consists of, in a first step, tuning some free parameters (with dependence on the signal BW and frequency of operation) of the LMBA to trade-off linearity and power efficiency. In a second step, two multipurpose adaptive digital predistortion (DPD) linearizers are considered, properly combined with crest factor reduction (CFR) techniques, to meet the required linearity specifications. Either a DPD based on artificial neural networks or a DPD based on polynomials can be selected taking into account the compromise between computational complexity and linearization performance. Experimental results will validate the proposed methodology to guarantee the linearity levels (ACPR < -45 dBc and EVM < 1%) with high power efficiency in an LMBA under dynamic transmission, where both the signal BW (from 20 and up to 200-MHz instantaneous BW) and frequency of operation (in the range of 1.8-2.4 GHz) change.This work was supported in part by the Spanish Government (Ministerio de Ciencia, Innovación y Universidades) and FEDER (Fondo Europeo de Desarrollo Regional) under Grant TEC2017-83343-C4-2-R and in part by the Generalitat de Catalunya under Grant 2017 SGR 813. This paper is an expanded version from the International Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits (INMMiC), Cardiff, United Kingdom, July 2020.Peer ReviewedPostprint (author's final draft

Glutaraldehyde in bio-catalysts design: a useful crosslinker and a versatile tool in enzyme immobilization

Glutaraldehyde is one of the most widely used reagents in the design of biocatalysts. It is a powerful crosslinker, able to react with itself, with the advantages that this may bring forth. In this review, we intend to give a general vision of its potential and the precautions that must be taken when using this effective reagent. First, the chemistry of the glutaraldehyde/amino reaction will be commented upon. This reaction is still not fully clarified, but it seems to be based on the formation of 6-membered heterocycles formed by 5 C and one O. Then, we will discuss the production of intra- and inter-molecular enzyme crosslinks (increasing enzyme rigidity or preventing subunit dissociation in multimeric enzymes). Special emphasis will be placed on the preparation of cross-linked enzyme aggregates (CLEAs), mainly in enzymes that have low density of surface reactive groups and, therefore, may be problematic to obtain a final solid catalyst. Next, we will comment on the uses of glutaraldehyde in enzymes previously immobilized on supports. First, the treatment of enzymes immobilized on supports that cannot react with glutaraldehyde (only inter and intramolecular cross-linkings will be possible) to prevent enzyme leakage and obtain some enzyme stabilization via cross-linking. Second, the cross-linking of enzymes adsorbed on aminated supports, where together with other reactions enzyme/support crosslinking is also possible; the enzyme is incorporated into the support. Finally, we will present the use of aminated supports preactivated with glutaraldehyde. Optimal glutaraldehyde modifications will be discussed in each specific case (one or two glutaraldehyde molecules for amino group in the support and/or the protein). Using preactivated supports, the heterofunctional nature of the supports will be highlighted, with the drawbacks and advantages that the heterofunctionality may have. Particular attention will be paid to the control of the first event that causes the immobilization depending on the experimental conditions to alter the enzyme orientation regarding the support surface. Thus, glutaraldehyde, an apparently old fashioned reactive, remains the most widely used and with broadest application possibilities among the compounds used for the design of biocatalyst

Strategies for the one-step immobilization–purification of enzymes as industrial biocatalysts

In this review, we detail the efforts performed to couple the purification and the immobilization of industrial enzymes in a single step. The use of antibodies, the development of specific domains with affinity for some specific supports will be revised. Moreover, we will discuss the use of domains that increase the affinity for standard matrices (ionic exchangers, silicates). We will show how the control of the immobilization conditions may convert some unspecific supports in largely specific ones. The development of tailor-made heterofunctional supports as a tool to immobilize–stabilize–purify some proteins will be discussed in deep, using low concentration of adsorbent groups and a dense layer of groups able to give an intense multipoint covalent attachment. The final coupling of mutagenesis and tailor made supports will be the last part of the review.This work has been supported by grant CTQ2013-41507-R from Spanish MINECO, grant no.1102-489-25428 from COLCIENCIAS and Universidad Industrial de Santander (VIE-UIS Research Program) (Colombia) and CNPq grant 403505/2013-5 (Brazil). A. Berenguer-Murcia thanks the Spanish MINECO for a Ramon y Cajal fellowship (RyC-2009-03813)

TIC y cocreación de valor en B2B: la nueva forma de fidelización en el servicio

[EN] In today’s competitive environment, it is emphasised that business digitalisation is one of the most important strategies to deal with new market challenges. This article argues that technology is a driving force behind business relationships, showing the origins of new ways to achieve loyalty. Through a model which has been tested in a sample of 256 travel agencies, technology can facilitate coordination in the management of relationships between tourism companies, promoting value co-creation between suppliers and customers. Co-creation in turn maximises trust and commitment between organisations and lays the foundations for achievement of dual social and economic satisfaction, for client companies, which ultimately enhances their loyalty. This research contributes to the literature in the interorganizational context, showing quantitative evidence on how technology triggers a sequence of effects that, through value co-creation, trust, and commitment in the channel, between agents in the tourism field, trace a new route of relationships that leads to the achievement of dual satisfaction and loyalty. Additionally, the interrelationships between the two satisfactions are analysed, concluding the mediating effect of economic satisfaction between social satisfaction and loyalty.[ES] En el entorno competitivo actual, se insiste en que la digitalización empresarial es una de las estrategias más im-portantes para hacer frente a los nuevos retos del mercado. En este artículo se argumenta que la tecnología es una fuerza impulsora de las relaciones comerciales, que muestra el origen de nuevos caminos hacia la consecución de la lealtad. A través de un modelo que ha sido probado en una muestra de 256 agencias de viajes, la tecnología puede facilitar la coordinación en la gestión de las relaciones entre las empresas turísticas, promoviendo la co-creación de valor entre proveedores y clientes. A su vez, la co-creación maximiza la confianza y el compromiso entre las organizaciones y sienta las bases para la consecución de una doble satisfacción social y económica, para las empresas clientes, lo que en última instancia aumenta su lealtad. Esta investigación contribuye a la literatura en el contexto interorganizacional, mostrando evidencias cuantitativas sobre cómo la tecnología desencadena una secuencia de efectos que, a través de la co-creación de valor, la confianza y el compromiso en el canal, entre agentes del ámbito turístico, traza una nueva ruta de relaciones que conduce a la consecución de la doble satisfacción y lealtad. Además, se analizan las interrelaciones entre ambas satisfacciones, concluyendo el efecto mediador de la satisfacción económica entre la satisfacción social y la lealtad.This research has been developed within the framework of the project grant PID2020-112660RB-I00 funded by MCIN/AEI/10.13039/501100011033 and the grant for consolidated re-search group AICO/2021/144 funded by the Conselleria d’Inno-vació, Universitats, Ciència i Societat Digital of the Generalitat Valenciana