Vicente Gotor-Fernández

Bio: Vicente Gotor-Fernández is an academic researcher from University of Oviedo. The author has contributed to research in topics: Lipase & Candida antarctica. The author has an hindex of 32, co-authored 178 publications receiving 3869 citations. Previous affiliations of Vicente Gotor-Fernández include University of the Free State & University of Edinburgh.

Candida antarctica Lipase B: An Ideal Biocatalyst for the Preparation of Nitrogenated Organic Compounds

Abstract: Candida antarctica lipase B (CAL-B) is a very effective catalyst for the production of amines and amides using different enzymatic procedures. Simplicity of use, low cost, commercial availability and recycling possibility make this lipase an ideal tool for the synthesis and resolution of a wide range of nitrogenated compounds that can be used for the production of pharmaceuticals and interesting manufactures in the industrial sector.

Lipases: Useful biocatalysts for the preparation of pharmaceuticals

Abstract: Biocatalysis offers a clean and ecological way to perform chemical processes, in mild reaction conditions and with high degree of selectivity. The use of enzymes, specially lipases, in organic solvents proves an excellent methodology for the preparation of single-isomer chiral drugs. This review covers some general aspects and representative examples of the use of lipases for the enantioselective or regioselective preparation of alcohol and amine intermediates in the synthesis of pharmaceuticals.

Hydrolases: Catalytically promiscuous enzymes for non-conventional reactions in organic synthesis

Abstract: During the last three decades the use of hydrolases for the catalysis of environmentally friendly organic processes under mild reaction conditions has been well documented. Hydrolases have shown themselves to be ideal tools for the acceleration of synthetic transformations because of their high stability, catalytic efficiency, commercial availability and broad substrate specificity in a wide spectrum of biocatalyzed processes. In recent years, novel examples have appeared related to non-conventional reactions catalyzed by hydrolytic enzymes. Amongst these, lipases and acylases have gained much attention as promiscuous biocatalysts showing good levels of reactivity in C–C bond formation, C–heteroatom bond formation, oxidative processes, and novel hydrolytic reactions. This critical review covers recent investigation in the field of catalytic promiscuity, and highlights the most surprising and uncommon activities that this class of enzymes shows in organic synthetic transformations (111 references).

Directed Evolution of an Amine Oxidase for the Preparative Deracemisation of Cyclic Secondary Amines

Abstract: Enantiomerically pure primary and secondary amines are widely used as chiral auxiliaries and resolving agents and are also valuable intermediates for the synthesis of pharmaceuticals and agrochemicals. Although enantiomerically pure amines are traditionally prepared by classical resolution of the corresponding racemate, alternative approaches have been developed based upon i) asymmetric reduction of imines, ii) hydroamination of alkenes and iii) lipase-catalysed kinetic resolution of racemic amines. However, secondary amines, many of which have pronounced biological activity, are poor substrates for lipases compared to the corresponding primary amines, with only a few documented examples in the literature. Hence the use of lipase resolution does not offer a general route to this class of chiral molecule. Moreover, to date it has generally not been possible to achieve the in situ racemisation of amines to effect a dynamic kinetic resolution process due to the relatively harsh conditions required to racemise amines. Against this backdrop, we sought to extend our chemo-enzymatic deracemisation method to encompass chiral secondary amines. Based upon our earlier work with a-amino acids, we recently reported the deracemisation of a-methylbenzyl amine (a-MBA, 1) in a one-pot procedure by the combined use of an enantioselective amine oxidase and ammonia borane as the reducing agent (Scheme 1). In order to identify an enzyme with appropriate activity and enantioselectivity towards a-methylbenzylamine, the amine oxidase from Aspergillus niger (MAO-N) was subjected to directed evolution, with (S)-1 as the probe substrate, by random mutagenesis and selection employing a high-throughput agarplate-based colorimetric screen. This approach led to the identification of an important amino acid substitution (Asn336Ser) that resulted in a variant enzyme possessing significantly enhanced activity (ca. 50-fold) and greater enantioselectivity towards 1 than the wild-type enzyme. Subsequently, we showed that this variant was also characterised by broad substrate specificity, being able to oxidize a wide range of chiral primary amines with high enantioselectivity. However, although this variant showed some activity towards chiral secondary amines (relative activity of 1-methyltetrahydroisoquinoline (MTQ, 2) 15 % of a-MBA), the rates of oxidation were too low to permit efficient preparative deracemisation reactions. Our goal therefore was to evolve a “secondary amine oxidase” for preparative-scale deracemisation reactions to complement the existing “primary amine oxidase”. The MAO-N gene used as the starting point for further directed evolution contained four amino acid substitutions compared to the wild-type. In addition to the Asn336Ser mutation, which is important for catalytic activity/enantioselectivity, mutations were Arg259Lys and Arg260Lys (improved expression) and Met348Lys (improved activity). This gene was subjected to random mutagenesis, by using the E. coli XL1-Red mutator strain (mutation frequency ca. 1–2 base changes per gene), followed by transformation and screening of the library (ca. 20 000 clones) against (R/S)-2 as the substrate, as previously described. A number of clones (ca. 10) showed greater activity than the parent, with one in particular appearing to be significantly more active. Purification of this variant amine oxidase showed that it possessed a kcat value about 5.5-fold higher than the parent towards (S)-2 (Table 1) and also a higher KM

Enzyme immobilisation in biocatalysis : Why, what and how

Abstract: In this tutorial review, an overview of the why, what and how of enzyme immobilisation for use in biocatalysis is presented. The importance of biocatalysis in the context of green and sustainable chemicals manufacture is discussed and the necessity for immobilisation of enzymes as a key enabling technology for practical and commercial viability is emphasised. The underlying reasons for immobilisation are the need to improve the stability and recyclability of the biocatalyst compared to the free enzyme. The lower risk of product contamination with enzyme residues and low or no allergenicity are further advantages of immobilised enzymes. Methods for immobilisation are divided into three categories: adsorption on a carrier (support), encapsulation in a carrier, and cross-linking (carrier-free). General considerations regarding immobilisation, regardless of the method used, are immobilisation yield, immobilisation efficiency, activity recovery, enzyme loading (wt% in the biocatalyst) and the physical properties, e.g. particle size and density, hydrophobicity and mechanical robustness of the immobilisate, i.e. the immobilised enzyme as a whole (enzyme + support). The choice of immobilisate is also strongly dependent on the reactor configuration used, e.g. stirred tank, fixed bed, fluidised bed, and the mode of downstream processing. Emphasis is placed on relatively recent developments, such as the use of novel supports such as mesoporous silicas, hydrogels, and smart polymers, and cross-linked enzyme aggregates (CLEAs).

Directed evolution drives the next generation of biocatalysts

Abstract: Enzymes are increasingly being used as biocatalysts in the generation of products that have until now been derived using traditional chemical processes. Such products range from pharmaceutical and agrochemical building blocks to fine and bulk chemicals and, more recently, components of biofuels. For a biocatalyst to be effective in an industrial process, it must be subjected to improvement and optimization, and in this respect the directed evolution of enzymes has emerged as a powerful enabling technology. Directed evolution involves repeated rounds of (i) random gene library generation, (ii) expression of genes in a suitable host and (iii) screening of libraries of variant enzymes for the property of interest. Both in vitro screening–based methods and in vivo selection–based methods have been applied to the evolution of enzyme function and properties. Significant developments have occurred recently, particularly with respect to library design, screening methodology, applications in synthetic transformations and strategies for the generation of new enzyme function.

Comprehensive Review in Current Developments of Imidazole‐Based Medicinal Chemistry

Abstract: Imidazole ring is an important five-membered aromatic heterocycle widely present in natural products and synthetic molecules. The unique structural feature of imidazole ring with desirable electron-rich characteristic is beneficial for imidazole derivatives to readily bind with a variety of enzymes and receptors in biological systems through diverse weak interactions, thereby exhibiting broad bioactivities. The related research and developments of imidazole-based medicinal chemistry have become a rapidly developing and increasingly active topic. Particularly, numerous imidazole-based compounds as clinical drugs have been extensively used in the clinic to treat various types of diseases with high therapeutic potency, which have shown the enormous development value. This work systematically gives a comprehensive review in current developments of imidazole-based compounds in the whole range of medicinal chemistry as anticancer, antifungal, antibacterial, antitubercular, anti-inflammatory, antineuropathic, antihypertensive, antihistaminic, antiparasitic, antiobesity, antiviral, and other medicinal agents, together with their potential applications in diagnostics and pathology. It is hoped that this review will be helpful for new thoughts in the quest for rational designs of more active and less toxic imidazole-based medicinal drugs, as well as more effective diagnostic agents and pathologic probes.