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Asymmetric and Selective Biocatalysis

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ISBN: 9783038978466 9783038978473 Year: Pages: 154 DOI: 10.3390/books978-3-03897-847-3 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Chemistry (General)
Added to DOAB on : 2019-06-26 09:16:44
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Abstract

This Issue contains one communication, six articles, and two reviews. The communication from Paola Vitale et al. represents a work where whole cells were used as biocatalysts for the reduction of optically active chloroalkyl arylketones followed by a chemical cyclization to give the desired heterocycles. Among the various whole cells screened (baker’s yeast, Kluyveromyces marxianus CBS 6556, Saccharomyces cerevisiae CBS 7336, Lactobacillus reuteri DSM 20016), baker’s yeast provided the best yields and the highest enantiomeric ratios (95:5) in the bioreduction of the above ketones. In this respect, valuable chiral non-racemic functionalized oxygen-containing heterocycles (e.g., (S)-styrene oxide, (S)-2-phenyloxetane, (S)-2-phenyltetrahydrofuran), amenable to be further elaborated on, can be smoothly and successfully generated from their prochiral precursors. Studies about pure biocatalysts with mechanistical studies, application in different reactions, and new immobilization methods for improving their stability were reported in five different articles. The article by Su-Yan Wang et al. describes the cloning, expression, purification, and characterization of an N-acetylglucosamine 2-epimerase from Pedobacter heparinus (PhGn2E). For this, several N-acylated glucosamine derivatives were chemically synthesized and used to test the substrate specificity of the enzyme. The mechanism of the enzyme was studied by hydrogen/deuterium NMR. The study at the anomeric hydroxyl group and C-2 position of the substrate in the reaction mixture confirmed the epimerization reaction via ring-opening/enolate formation. Site-directed mutagenesis was also used to confirm the proposed mechanism of this interesting enzyme. The article by Forest H. Andrews et al. studies two enzymes, benzoylformate decarboxylase (BFDC) and pyruvate decarboxylase (PDC), which catalyze the non-oxidative decarboxylation of 2-keto acids with different specificity. BFDC from Pseudomonas putida exhibited very limited activity with pyruvate, whereas the PDCs from S. cerevisiae or from Zymomonas mobilis showed virtually no activity with benzoylformate (phenylglyoxylate). After studies using saturation mutagenesis, the BFDC T377L/A460Y variant was obtained, with 10,000-fold increase in pyruvate/benzoylformate. The change was attributed to an improvement in the Km value for pyruvate and a decrease in the kcat value for benzoylformate. The characterization of the new catalyst was performed, providing context for the observed changes in the specificity. The article by Xin Wang et al. compares two types of biocatalysts to produce D-lysine L-lysine in a cascade process catalyzed by two enzymes: racemase from microorganisms that racemize L-lysine to give D,L-lysine and decarboxylase that can be in cells, permeabilized cells, and the isolated enzyme. The comparison between the different forms demonstrated that the isolated enzyme showed the higher decarboxylase activity. Under optimal conditions, 750.7 mmol/L D-lysine was finally obtained from 1710 mmol/L L-lysine after 1 h of racemization reaction and 0.5 h of decarboxylation reaction. D-lysine yield could reach 48.8% with enantiomeric excess (ee) of 99%. In the article by Rivero and Palomo, lipase from Candida rugosa (CRL) was highly stabilized at alkaline pH in the presence of PEG, which permitted its immobilization for the first time by multipoint covalent attachment on different aldehyde-activated matrices. Different covalent immobilized preparation of the enzyme was successfully obtained. The thermal and solvent stability was highly increased by this treatment, and the novel catalysts showed high regioselectivity in the deprotection of per-O-acetylated nucleosides. The article by Robson Carlos Alnoch et al. describes the protocol and use of a new generation of tailor-made bifunctional supports activated with alkyl groups that allow the immobilization of proteins through the most hydrophobic region of the protein surface and aldehyde groups that allows the covalent immobilization of the previously adsorbed proteins. These supports were especially used in the case of lipase immobilization. The immobilization of a new metagenomic lipase (LipC12) yielded a biocatalyst 3.5-fold more active and 5000-fold more stable than the soluble enzyme. The PEGylated immobilized lipase showed high regioselectivity, producing high yields of the C-3 monodeacetylated product at pH 5.0 and 4 °C. Hybrid catalysts composed of an enzyme and metallic complex are also treated in this Special Issue. The article by Christian Herrero et al. describes the development of the Mn(TpCPP)-Xln10A artificial metalloenzyme, obtained by non-covalent insertion of Mn(III)-meso-tetrakis(p-carboxyphenyl)porphyrin [Mn(TpCPP), 1-Mn] into xylanase 10A from Streptomyces lividans (Xln10A). The complex was found able to catalyze the selective photo-induced oxidation of organic substrates in the presence of [RuII(bpy)3]2+ as a photosensitizer and [CoIII(NH3)5Cl]2+ as a sacrificial electron acceptor, using water as oxygen atom source. The two published reviews describe different subjects with interest in the fields of biocatalysis and mix metallic-biocatalysis, respectively. The review by Anika Scholtissek et al. describes the state-of-the-art regarding ene-reductases from the old yellow enzyme family (OYEs) to catalyze the asymmetric hydrogenation of activated alkenes to produce chiral products with industrial interest. The dependence of OYEs on pyridine nucleotide coenzyme can be avoided by using nicotinamide coenzyme mimetics. In the review, three main classes of OYEs are described and characterized. The review by Yajie Wang and Huimin Zhao highlights some of the recent examples in the past three years that combine transition metal catalysis with enzymatic catalysis. With recent advances in protein engineering, catalyst synthesis, artificial metalloenzymes, and supramolecular assembly, there is great potential to develop more sophisticated tandem chemoenzymatic processes for the synthesis of structurally complex chemicals. In conclusion, these nine publications give an overview of the possibilities of different catalysts, both traditional biocatalysts and hybrids with metals or organometallic complexes to be used in different processes—particularly in synthetic reactions—under very mild reaction conditions.

Plant Genetics and Molecular Breeding

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ISBN: 9783039211753 9783039211760 Year: Pages: 628 DOI: 10.3390/books978-3-03921-176-0 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Biology
Added to DOAB on : 2019-08-28 11:21:27
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Abstract

The development of new plant varieties is a long and tedious process involving the generation of large seedling populations for the selection of the best individuals. While the ability of breeders to generate large populations is almost unlimited, the selection of these seedlings is the main factor limiting the generation of new cultivars. Molecular studies for the development of marker-assisted selection (MAS) strategies are particularly useful when the evaluation of the character is expensive, time-consuming, or with long juvenile periods. The papers published in the Special Issue “Plant Genetics and Molecular Breeding” report highly novel results and testable new models for the integrative analysis of genetic (phenotyping and transmission of agronomic characters), physiology (flowering, ripening, organ development), genomic (DNA regions responsible for the different agronomic characters), transcriptomic (gene expression analysis of the characters), proteomic (proteins and enzymes involved in the expression of the characters), metabolomic (secondary metabolites), and epigenetic (DNA methylation and histone modifications) approaches for the development of new MAS strategies. These molecular approaches together with an increasingly accurate phenotyping will facilitate the breeding of new climate-resilient varieties resistant to abiotic and biotic stress, with suitable productivity and quality, to extend the adaptation and viability of the current varieties.

Keywords

sugarcane --- cry2A gene --- particle bombardment --- stem borer --- resistance --- NPK fertilizers --- agronomic traits --- molecular markers --- quantitative trait loci --- common wild rice --- Promoter --- Green tissue-specific expression --- light-induced --- transgenic chrysanthemum --- WRKY transcription factor --- salt stress --- gene expression --- DgWRKY2 --- Cucumis sativus L. --- RNA-Seq --- DEGs --- sucrose --- ABA --- drought stress --- Aechmea fasciata --- squamosa promoter binding protein-like --- flowering time --- plant architecture --- bromeliad --- Oryza sativa --- endosperm development --- rice quality --- WB1 --- the modified MutMap method --- abiotic stress --- Cicer arietinum --- candidate genes --- genetics --- heat-stress --- molecular breeding --- metallothionein --- Brassica --- Brassica napus --- As3+ stress --- broccoli --- cytoplasmic male sterile --- bud abortion --- gene expression --- transcriptome --- RNA-Seq --- sesame --- genome-wide association study --- yield --- QTL --- candidate gene --- cabbage --- yellow-green-leaf mutant --- recombination-suppressed region --- bulk segregant RNA-seq --- differentially expressed genes --- marker–trait association --- haplotype block --- genes --- root traits --- D-genome --- genotyping-by-sequencing --- single nucleotide polymorphism --- durum wheat --- bread wheat --- complex traits --- Brassica oleracea --- Ogura-CMS --- iTRAQ --- transcriptome --- pollen development --- rice --- OsCDPK1 --- seed development, starch biosynthesis --- endosperm appearance --- Chimonanthus praecox --- nectary --- floral scent --- gene expression --- Prunus --- flowering --- bisulfite sequencing --- genomics --- epigenetics --- breeding --- AP2/ERF genes --- Bryum argenteum --- transcriptome --- gene expression --- stress tolerance --- SmJMT --- transgenic --- Salvia miltiorrhiza --- overexpression --- transcriptome --- phenolic acids --- Idesia polycarpa var --- glycine --- FAD2 --- linoleic acid --- oleic acid --- anther wall --- tapetum --- pollen accumulation --- OsGPAT3 --- rice --- cytoplasmic male sterility (CMS) --- phytohormones --- differentially expressed genes --- pollen development --- Brassica napus --- Rosa rugosa --- RrGT2 gene --- Clone --- VIGS --- Overexpression --- Tobacco --- Flower color --- Anthocyanin --- sugarcane --- WRKY --- subcellular localization --- gene expression pattern --- protein-protein interaction --- transient overexpression --- soybean --- branching --- genome-wide association study (GWAS) --- near-isogenic line (NIL) --- BRANCHED1 (BRC1) --- TCP transcription factor --- Zea mays L. --- MADS transcription factor --- ZmES22 --- starch --- flowering time --- gene-by-gene interaction --- Hd1 --- Ghd7 --- rice --- yield trait --- Oryza sativa L. --- leaf shape --- yield trait --- molecular breeding --- hybrid rice --- nutrient use efficiency --- quantitative trait loci (QTLs), molecular markers --- agronomic efficiency --- partial factor productivity --- P. suffruticosa --- R2R3-MYB --- overexpression --- anthocyanin --- transcriptional regulation --- ethylene-responsive factor --- Actinidia deliciosa --- AdRAP2.3 --- gene expression --- waterlogging stress --- regulation --- Chrysanthemum morifolium --- WUS --- CYC2 --- gynomonoecy --- reproductive organ --- flower symmetry --- Hs1pro-1 --- cZR3 --- gene pyramiding --- Heterodera schachtii --- resistance --- tomato --- Elongated Internode (EI) --- QTL --- GA2ox7 --- n/a

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