PURIFICACIÓN E INMOVILIZACIÓN DE ENZIMAS INDUSTRIALES

La purificación e inmovilización sencilla y correcta de una enzima nos permitirá diseñar biocatalizadores heterogéneos con una gran cantidad de enzima por gramo de catalizador y un elevado porcentaje de actividad catalítica por molécula de enzima. También existen protocolos de inmovilización que nos permiten mejorar notablemente las propiedades funcionales de las enzimas: actividad, estabilidad, selectividad, posibilidades de reactivación, etc. De este modo, la implantación masiva de las enzimas como catalizadores industriales será cada día más sencilla

Nuevos catalizadores altamente estabilizados de la enzima β-galactosidasa de Kluyveromyces lactis inmovilizada sobre soportes glioxil

La presente invención se refiere a un procedimiento de estabilización de una β-galactosidasa de Kluyveromyces lactis, preferentemente inmovilizada en un soporte, que comprende unir la enzima a un polímero activado con al menos un agente conservante de estabilización de enzimas, dicho polímero activado comprendiendo grupos aldehído y/o carboxilo, y donde la unión es de tipo covalente y/o electrostática entre al menos un grupo amino de la enzima con un grupo aldehído o carboxilo del polímero activado. Es asimismo objeto de la presente invención, el catalizador de β-galactosidasa de Kluyveromyces lactis obtenido por el procedimiento anterior, así como sus diferentes usos tales como la hidrólisis de lactosa en leche y sueros ácidos, la síntesis de galactooligosacáridos o su uso en reactores de tanque agitado, de lecho fijo o de lecho fluidizadoPeer reviewedConsejo Superior de Investigaciones CientíficasA1 Solicitud de adición a la patent

Engineering the substrate specificity of a thermophilic penicillin acylase from thermus thermophilus

A homologue of the Escherichia coli penicillin acylase is encoded in the genomes of several thermophiles, including in different Thermus thermophilus strains. Although the natural substrate of this enzyme is not known, this acylase shows a marked preference for penicillin K over penicillin G. Three-dimensional models were created in which the catalytic residues and the substrate binding pocket were identified. Through rational redesign, residues were replaced to mimic the aromatic binding site of the E. coli penicillin G acylase. A set of enzyme variants containing between one and four amino acid replacements was generated, with altered catalytic properties in the hydrolyses of penicillins K and G. The introduction of a single phenylalanine residue in position α188, α189, or β24 improved the Km for penicillin G between 9- and 12-fold, and the catalytic efficiency of these variants for penicillin G was improved up to 6.6-fold. Structural models, as well as docking analyses, can predict the positioning of penicillins G and K for catalysis and can demonstrate how binding in a productive pose is compromised when more than one bulky phenylalanine residue is introduced into the active site. © 2013, American Society for Microbiology.Spanish Ministry of Science (CIT no. 010000-2009-29, RyC2006-02441, and BIO2010-18875); Fundación Ramón ArecesPeer Reviewe

Protein hydrolysis by immobilized and stabilized trypsin

El pdf del artículo es la versión pre-print.-- et al.The preparation of novel immobilized and stabilized derivatives of trypsin is reported here. The new derivatives preserved 80% of the initial catalytic activity toward synthetic substrates [benzoyl-arginine p-nitroanilide (BAPNA)] and were 50,000-fold more thermally stable than the diluted soluble enzyme in the absence of autolysis. Trypsin was immobilized on highly activated glyoxyl-Sepharose following a two-step immobilization strategy: (a) first, a multipoint covalent immobilization at pH 8.5 that only involves low pKa amino groups (e.g., those derived from the activation of trypsin from trypsinogen) is performed and (b) next, an additional alkaline incubation at pH 10 is performed to favor an intense, additional multipoint immobilization between the high concentration of proximate aldehyde groups on the support surface and the high pKa amino groups at the enzyme surface region that participated in the first immobilization step. Interestingly, the new, highly stable trypsin derivatives were also much more active in the proteolysis of high molecular weight proteins when compared with a nonstabilized derivative prepared on CNBr-activated Sepharose. In fact, all the proteins contained a cheese whey extract had been completely proteolyzed after 6 h at pH 9 and 50°C, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Under these experimental conditions, the immobilized biocatalysts preserve more than 90% of their initial activity after 20 days. Analysis of the three-dimensional (3D) structure of the best immobilized trypsin derivative showed a surface region containing two amino terminal groups and five lysine (Lys) residues that may be responsible for this novel and interesting immobilization and stabilization. Moreover, this region is relatively far from the active site of the enzyme, which could explain the good results obtained for the hydrolysis of high-molecular weight proteins. © 2011 American Institute of Chemical Engineers (AIChE).Peer Reviewe

High Stabilization of Enzymes Immobilized on Rigid Hydrophobic Glyoxyl-Supports: Generation of Hydrophilic Environments on Support Surfaces

© 2020 by the authors.Very rigid supports are useful for enzyme immobilization to design continuous flow reactors and/or to work in non-conventional media. Among them, epoxy-methacrylic supports are easily functionalized with glyoxyl groups, which makes them ideal candidates for enzyme stabilization via multipoint covalent immobilization. However, these supports present highly hydrophobic surfaces, which might promote very undesirable effects on enzyme activity and/or stability. The hydrophilization of the support surface after multipoint enzyme immobilization is proposed here as an alternative to reduce these undesirable effects. The remaining aldehyde groups on the support are modified with aminated hydrophilic small molecules (glycine, lysine or aspartic acid) in the presence of 2-picoline borane. The penicillin G acylase from Escherichia coli (PGA) and alcohol dehydrogenase from Thermus thermophilus HB27 (ADH2) were immobilized on glyoxyl-functionalized agarose, Relizyme and Relisorb. Despite the similar density of aldehyde groups displayed by functionalized supports, their stabilization effects on immobilized enzymes were quite different: up to 300-fold lower by hydrophobic supports than by highly hydrophilic glyoxyl-agarose. A dramatic increase in the protein stabilities was shown when a hydrophilization treatment of the hydrophobic support surface was done. The PGA immobilized on the glyoxyl-Relisorb hydrophilized with aspartic acid becomes 280-fold more stable than without any treatment, and it is even more stable than the PGA immobilized on the glyoxyl agarose.This research was funded by the Spanish Ministry of Economy, Industry and Competitiveness (projects BIO2012-36861 and CTQ2015-70348) and the EU FP7 project SuSy (Sucrose Synthase as Cost-Effective Mediator of Glycosylation Reactions, C-KBBE/3293). Javier Rocha-Martin is grateful for the Juan de la Cierva fellowship (IJCI-2014-19260) funded by the Spanish Ministry of Economy, Industry and Competitiveness.Peer reviewe

A Novel Halophilic Lipase, LipBL, Showing High Efficiency in the Production of Eicosapentaenoic Acid (EPA)

Background: Among extremophiles, halophiles are defined as microorganisms adapted to live and thrive in diverse extreme saline environments. These extremophilic microorganisms constitute the source of a number of hydrolases with great biotechnological applications. The interest to use extremozymes from halophiles in industrial applications is their resistance to organic solvents and extreme temperatures. Marinobacter lipolyticus SM19 is a moderately halophilic bacterium, isolated previously from a saline habitat in South Spain, showing lipolytic activity. Methods and Findings: A lipolytic enzyme from the halophilic bacterium Marinobacter lipolyticus SM19 was isolated. This enzyme, designated LipBL, was expressed in Escherichia coli. LipBL is a protein of 404 amino acids with a molecular mass of 45.3 kDa and high identity to class C b-lactamases. LipBL was purified and biochemically characterized. The temperature for its maximal activity was 80uC and the pH optimum determined at 25uC was 7.0, showing optimal activity without sodium chloride, while maintaining 20% activity in a wide range of NaCl concentrations. This enzyme exhibited high activity against short-medium length acyl chain substrates, although it also hydrolyzes olive oil and fish oil. The fish oil hydrolysis using LipBL results in an enrichment of free eicosapentaenoic acid (EPA), but not docosahexaenoic acid (DHA), relative to its levels present in fish oil. For improving the stability and to be used in industrial processes LipBL was immobilized in different supports. The immobilized derivatives CNBr-activated Sepharose were highly selective towards the release of EPA versus DHA. The enzyme is also active towards different chiral and prochiral esters. Exposure of LipBL to buffer-solvent mixtures showed that the enzyme had remarkable activity and stability in all organic solvents tested. Conclusions: In this study we isolated, purified, biochemically characterized and immobilized a lipolytic enzyme from a halophilic bacterium M. lipolyticus, which constitutes an enzyme with excellent properties to be used in the food industry, in the enrichment in omega-3 PUFAs

Dextran-coated nanoparticles as immunosensing platforms: Consideration of polyaldehyde density, nanoparticle size and functionality

Magnetic nanoparticles (MNPs) can be used as antibody carriers in a wide range of immunosensing applications. The conjugation chemistry for preparing antibody-MNP bionanohybrids should assure the nanoparticle’s colloidal dispersity, directional conformation and high biofunctionality retention of attached antibodies. In this work, peroxidase (HRP) was selected as model target analyte, and stable antibody-MNP conjugates were prepared using polyaldehyde-dextrans as multivalent linkers, also to prevent nanoparticles agglomeration and steric shielding of non-specific proteins. Under the manipulation of the oxidation variables, MNP-conjugated antibody showed the highest Fab accessibility, of 1.32 μmol analyte per μmol antibody, corresponding to 139 μmol aldehyde per gram of nanocarrier (5 mM NaIO4, 4 h). Demonstrating anti-interference advantage up to 10% serum, colorimetric immunoassay gave a detection limit (LOD) of 300 ng mL− 1 , while electrochemical transduction led to a considerable (680 times) improvement, with a LOD of 0.44 ng mL− 1 . In addition, polyaldehydedextran showed priority over polycarboxylated-dextran as the multivalent antibody crosslinker for MNPs in terms of sensitivity and LOD value, while immunosensors constructed with carboxylated magnetic microbeads (HOOC-MBs) outperformed MNPs-based immunoplatforms. This work sheds light on the importance of surface chemistry (type and density of functional groups) and the dimension (nanosize vs micrometer) of magnetic carriers to conjugate antibodies with better directional orientation and improve the analytical performance of the resulting immunosensors

Human breast milk microRNAs, potential players in the regulation of nervous system

Human milk is the biological fluid with the highest exosome amount and is rich in microRNAs (miRNAs). These are key regulators of gene expression networks in both normal physiologic and disease contexts, miRNAs can influence many biological processes and have also shown promise as biomarkers for disease. One of the key aspects in the regeneration of the nervous system is that there are practically no molecules that can be used as potential drugs. In the first weeks of lactation, we know that human breast milk must contain the mechanisms to transmit molecular and biological information for brain development. For this reason, our objective is to identify new modulators of the nervous system that can be used to investigate neurodevelopmental functions based on miRNAs. To do this, we collected human breast milk samples according to the time of delivery and milk states: mature milk and colostrum at term; moderate and very preterm mature milk and colostrum; and late preterm mature milk. We extracted exosomes and miRNAs and realized the miRNA functional assays and target prediction. Our results demonstrate that miRNAs are abundant in human milk and likely play significant roles in neurodevelopment and normal function. We found 132 different miRNAs were identified across all samples. Sixty-nine miRNAs had significant differential expression after paired group comparison. These miRNAs are implicated in gene regulation of dopaminergic/glutamatergic synapses and neurotransmitter secretion and are related to the biological process that regulates neuron projection morphogenesis and synaptic vesicle transport. We observed differences according to the delivery time and with less clarity according to the milk type. Our data demonstrate that miRNAs are abundant in human milk and likely play significant roles in neurodevelopment and normal function.Sociedad de Pediatría Gallega | Ref. BecaSOPEGA2016Axencia Galega de Innovación | Ref. IN607B-2018/17Axencia Galega de Innovación | Ref. PI20/00937Axencia Galega de Innovación | Ref. IN606A-2019/02

Copper-catalyzed diastereo- and enantioselective desymmetrization of cyclopropenes: Synthesis of cyclopropylboronates

This document is the accepted manuscript version of a Published Work that appeared in final form in Journal of American Chemical Society 136.45, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see DOI: 10.1021/ja510419zA novel Cu-catalyzed diastereo- and enantioselective desymmetrization of cyclopropenes to afford nonracemic cyclopropylboronates is described. Trapping the cyclopropylcopper intermediate with electrophilic amines allows for the synthesis of cyclopropylaminoboronic esters and demonstrates the potential of the approach for the synthesis of functionalized cyclopropanesWe thank the European Research Council (ERC-337776) and MINECO (CTQ2012-35957) for financial support. M. T. and A. P. thank MICINN for RyC and JdC contract

New opportunities for immobilization of enzymes

In this chapter, as a general introduction, we summarize our personal point of view on immobilization technique in order to prepare optimal and cost-effective biocatalysts. Special attention is paid to the improvement of enzyme properties via immobilization techniques. From the stabilization by multipoint covalent attachment to the generation of hydrophilic environments via post-immobilization techniques are here discussed. Immobilization techniques, a necessary tool to reuse enzyme, have to be simple and, if possible, may become a very powerful tool to greatly improve properties of every kind of enzymes: monomeric, multimeric, stable, labile, poorly selective, etc.Peer Reviewe