Hemopathogens in naturally infected bovine fetuses in Brazil.

The transplacental transmission of parasites and hemoparasites is crucial for understanding the epidemiology of diseases. This study aimed to assess the prevalence of hemopathogens in bovine fetuses at various gestational periods. Samples were obtained from a slaughterhouse in the state of Minas Gerais, Brazil, and a total of 236 fetuses were collected. DNA extracted from blood samples (145) and organ samples (a pool of brain and spleen) (236) underwent a nested PCR (nPCR) assay to detect Babesia spp., Theileria spp., Trypanosoma vivax, Anaplasma marginale, Anaplasma bovis, Anaplasma phagocytophilum, Ehrlichia minasensis, and hemotropic Mycoplasma spp. Additionally, serological analysis of 145 plasma samples was conducted using the indirect fluorescent antibody test-IFAT to detect IgG against Babesia bovis, Babesia bigemina, A. marginale, and Trypanosoma vivax. The observed prevalence of transplacental transmission was 19.3 %, 6.2 %, 42.7 % and 2.7 %, for A. marginale, B. bigemina, 'Candidatus M. haemobos', and Mycoplasma wenyonii, respectively. The prevalence of A. marginale by gestational trimester was 16 % (13/81) in the second trimester and 23 % (14/60) in the third trimester, with no positive samples in the first trimester. Regarding the species B. bovis and B. bigemina, all evaluated animals tested negative by nPCR, and no serological evidence for B. bovis was found by the IFAT. Babesia bigemina demonstrated an overall seroprevalence of 6.2 % (9/145), with 4.8 % (7/145) in the last trimester and 1.3 % (2/145) in the second trimester of pregnancy. In total, 42.7 % (62/145) of blood samples were positive for 'Candidatus M. haemobos', with 42 % (34/81) in the middle trimester, and 43 % (26/60) in the final trimester of pregnancy. Mycoplasma wenyonni was detected in 2.7 % (4/145) blood samples, all in coinfection with 'C. M. haemobos'. The prevalence by pregnancy trimester was 25 % (1/4) in the first trimester; 1.2 % (1/81) in the second trimester and 3.3 % (2/60) in the third trimester of pregnancy. Hemopathogen DNA was detected in fetus blood samples but not the brain or spleen samples. All the samples were negative for T. vivax, Theileria spp., Anaplasma spp. and Ehrlichia spp. Overall, in this study, approximately 70 % of fetuses were positive for one or more of the studied parasites. No significant associations were observed between pairs of pathogens, except 'C. M. haemobos' and A. marginale.

Urea Decomposition Mechanism by Dinuclear Nickel Complexes.

Urease is an enzyme containing a dinuclear nickel active center responsible for the hydrolysis of urea into carbon dioxide and ammonia. Interestingly, inorganic models of urease are unable to mimic its mechanism despite their similarities to the enzyme active site. The reason behind the discrepancy in urea decomposition mechanisms between inorganic models and urease is still unknown. To evaluate this factor, we synthesized two bis-nickel complexes, [Ni2L(OAc)] (1) and [Ni2L(Cl)(Et3N)2] (2), based on the Trost bis-Pro-Phenol ligand (L) and encompassing different ligand labilities with coordination geometries similar to the active site of jack bean urease. Both mimetic complexes produced ammonia from urea, (1) and (2), were ten- and four-fold slower than urease, respectively. The presence and importance of several reaction intermediates were evaluated both experimentally and theoretically, indicating the aquo intermediate as a key intermediate, coordinating urea in an outer-sphere manner. Both complexes produced isocyanate, revealing an activated water molecule acting as a base. In addition, the reaction with different substrates indicated the biomimetic complexes were able to hydrolyze isocyanate. Thus, our results indicate that the formation of an outer-sphere complex in the urease analogues might be the reason urease performs a different mechanism.

Essential role of extracytoplasmic proteins in the resistance of Gluconacetobacter diazotrophicus to cadmium.

Cadmium (Cd) is a heavy metal used as raw material for several fertilizers and pesticides. The increase of Cd concentration in soils has been observed in cultivated areas, affecting animals, plants, and microorganisms. Gluconacetobacter diazotrophicus is a plant growth-promoting bacterium able to survive under adverse environmental conditions. Here, we investigated key mechanisms involved with the resistance of G. diazotrophicus to Cd. Proteomic analyses revealed that the main pathways regulated in response to Cd are nutrient uptake, multidrug efflux pumps, response to oxidative stress, and protein quality control system. Extracytoplasmic proteins related to multidrug efflux pumps were up-accumulated, while several proteins related to nutrients uptake were down-accumulated. The relevance of these pathways for bacterial resistance to Cd was investigated by reverse genetic analysis using mutants defective for nutrient uptake (tdbr, ompW, and oprB), multidrug efflux (czcC), response to oxidative stress (ggt), and protein quality control system (clpX). Our data demonstrated the essential role of the tdbr and czcC genes for resistance to Cd in G. diazotrophicus. These results contribute to a better understanding of the resistance mechanisms to Cd in G. diazotrophicus, shedding light on responses associated with extracytoplasmic compartments.

Ultrasound-mediated radical cascade reactions: Fast synthesis of functionalized indolines from 2-(((N-aryl)amino)methyl)acrylates.

Novel functionalized indolines were synthesized from 2-(((N-aryl)amino)methyl)acrylates and formamides under ultrasonic irradiation for the first time. Aiming to develop a straightforward and easy-to-implement methodology for the synthesis of indolines, an instrumentation setup was designed, including ultrasound (US) equipment (Ultrasonic Horn; tip diameter of 12.7 mm, 20 kHz, maximum power of 400 W), an open reaction flask, and an inexpensive and green catalyst (1 mol%; FeSO4·7H2O; CAS: 7782-63-0) without the need for anhydrous conditions. The use of the sono-Fenton process in the presence of formamides and 2-(((N-aryl)amino)methyl)acrylates afforded a broad range of functionalized indolines within 60 s in high yields. Several experimental parameters of the ultrasound-assisted reaction were evaluated, such as amplitude (40-80%), sonication time (15-60 s), and pulsed ultrasonic irradiation. A 60 s silent reaction did not produce the desired indoline. The optimized conditions for US-mediated reactions allowed the production of functionalized indolines in high isolated yields (up to 99%, 60 s reaction, pulse ration 1 s:1 s, US amplitude 60 %).

Combination of osmotic stress and sugar stress response mechanisms is essential for Gluconacetobacter diazotrophicus tolerance to high-sucrose environments.

Sugar-rich environments represent an important challenge for microorganisms. The osmotic and molecular imbalances resulting from this condition severely limit microbial metabolism and growth. Gluconacetobacter diazotrophicus is one of the most sugar-tolerant prokaryotes, able to grow in the presence of sucrose concentrations up to 30%. However, the mechanisms that control its tolerance to such conditions remain poorly exploited. The present work investigated the key mechanisms of tolerance to high sugar in G. diazotrophicus. Comparative proteomics was applied to investigate the main functional pathways regulated in G. diazotrophicus when cultivated in the presence of high sucrose. Among 191 proteins regulated by high sucrose, regulatory pathways related to sugar metabolism, nutrient uptake, compatible solute synthesis, amino acid metabolism, and proteolytic system were highlighted. The role of these pathways on high-sucrose tolerance was investigated by mutagenesis analysis, which revealed that the knockout mutants zwf::Tn5 (sugar metabolism), tbdr::Tn5 (nutrient uptake), mtlK::Tn5 (compatible solute synthesis), pepN::Tn5 (proteolytic system), metH::Tn5 (amino acid metabolism), and ilvD::Tn5 (amino acid metabolism) became more sensitive to high sucrose. Together, our results identified mechanisms involved in response to high sugar in G. diazotrophicus, shedding light on the combination of osmotolerance and sugar-tolerance mechanisms. KEY POINTS: • G. diazotrophicus intensifies glycolysis to metabolize the excess of sugar. • G. diazotrophicus turns down the uptake of nutrients in response to high sugar. • G. diazotrophicus requires amino acid availability to resist high sugar.

New detection of the occurrence of trypanosomiasis in a bovine herd in a rural property in the state of Bahia/BA ­ case report / Nova detecção da ocorrência de tripanossomíase em rebanho bovino em propriedade rural no estado da Bahia/BA ­ relato de caso

This report aims to discuss the occurrence of protozoan infestation in a Girolanda cattle herd in the state of Bahia / BA. Bovine trypanosomiasis is a severe disease that is harmful to cattle, inducing large productive and economic losses. The animals are affected by protozoa of the genus Trypanosoma spp., giving rise to infestations in the vast majority of them in a silent and lasting way. In the Bahian rural property described, 10% of adult cows died and the rest of the animals showed clinical signs of anemia, drop in milk production, low body score, apathy, among others. Among the information obtained through the farm manager, who helped in the diagnosis and in ordering tests for the respective disease were: purchase of cattle from the region of the state of Minas Gerais and dubious management of oxytocin for improvements in milk production (suspected shared needles). Faced with the suspicion and in conjunction with the information obtained, laboratory tests and molecular tests were carried out to confirm the suspicion. After the examinations, it was found that the animals were affected by protozoa of the genus Trypanossoma vivax. The animals were treated with volume replenishers and drugs such as isometamidium chloride in a single dose calculated according to the body weight.

O presente relato tem por objetivo discorrer sobre a ocorrência da infestação protozoária em um rebanho bovino da raça Girolanda no estado da Bahia/BA. A tripanossomíase bovina é uma doença severa e prejudicial aos bovinos, induzindo-os a grandes perdas produtivas e econômicas. Os animais são afetados por protozoários do gênero Trypanosoma spp., dandoorigem a infestações em sua grande maioria de forma silenciosa e duradoura. Na propriedade rural baiana descrita, 10% das vacas adultas morreram e o restante dos animais apresentava sinais clínicos de anemia, queda da produção leiteira, baixo escore corpóreo, apatia, prostração, entre outros. Dentre as informações obtidas através do gerente da fazenda, que auxiliaram no diagnóstico e na requisição de exames para a respectiva doença estavam: compra de bovinos da região do estado de Minas Gerais e manejo duvidoso de ocitocina para melhorias na produção leiteira (suspeita de agulhas compartilhadas). Diante da suspeita e em conjunto com informações obtidas, foram realizados exames laboratoriais e testes moleculares para confirmar a suspeita. Após a realização dos exames, constatou-se que os animais estavam acometidos por protozoários do gênero Trypanossoma vivax. Os animais foram tratados com repositores de volume e fármacos como o cloreto de isometamidium em uma única dose calculada de acordo com o peso corpóreo.

Cascade Reactions Assisted by Microwave Irradiation: Ultrafast Construction of 2-Quinolinone-Fused γ-Lactones from N-(o-Ethynylaryl)acrylamides and Formamide.

An ultrafast (10 s) methodology to construct novel highly functionalized 2-quinolinones from N-(o-ethynylaryl)acrylamides (1,7-enynes) is described for the first time. Microwave irradiation enabled the ultrafast synthesis of 2-quinolinone-fused γ-lactones from Fenton's reagents in formamide. After six key consecutive reactions, including a diastereoselective step, 2-quinolinone-fused γ-lactones were obtained in good overall yield (up to 46%; 10 s).

Home physical exercise improves functional mobility and quality of life in the elderly: A CONSORT-prospective, randomised controlled clinical trial.

AIMS: To test the hypothesis of a semi-supervised home physical exercise programme that is likely to improve the functional mobility and quality of life (QOL) of elderly in the community. METHODS: This trial included elderly adults (88% female) aged 60 years or older and who were sedentary and without cognitive decline. The participants were randomly assigned to an intervention group (IG, home physical exercise and sleep hygiene) and a control group (CG, sleep hygiene). The International Questionnaire on Physical Activity, mental state mini-exam, World Health Organization Quality of Life Instrument-Older Adults Module (WHOQOL-OLD) and the Timed Up and Go (TUG) tests were conducted before and after the 12-week intervention period. RESULTS: The study was concluded with 125 elderly participants. Anthropometric data were indicative of pre-obesity, with a mean body mass index of 27.3 ± 4, a low-income socio-economic profile (78% ≤ 2 SM) and low schooling rates (76% ≤ 3 years of study). Most of the elderly (87%) were considered physically active with IPAQ > 150 min/week. The group of elderly people who performed the home physical exercise programme showed a significant improvement in functional mobility according to the time of execution of the TUG test before (9.1 ± 2) and after (7.1 ± 1) with an average reduction of 2 ± 1 s (P < .01). The difference in the QOL of the elderly who participated in the exercise protocol was also observed, verified through the WHOQOL-OLD global score, which presented an initial score of 85 ± 10, changing to 90.4 ± 9 after the intervention. CONCLUSION: Semi-supervised physical home exercise is safe and effective in improving the functional mobility and QOL of sedentary elderly people in the community.

Flow Biocatalysis: A Challenging Alternative for the Synthesis of APIs and Natural Compounds.

Biocatalysts represent an efficient, highly selective and greener alternative to metal catalysts in both industry and academia. In the last two decades, the interest in biocatalytic transformations has increased due to an urgent need for more sustainable industrial processes that comply with the principles of green chemistry. Thanks to the recent advances in biotechnologies, protein engineering and the Nobel prize awarded concept of direct enzymatic evolution, the synthetic enzymatic toolbox has expanded significantly. In particular, the implementation of biocatalysts in continuous flow systems has attracted much attention, especially from industry. The advantages of flow chemistry enable biosynthesis to overcome well-known limitations of "classic" enzymatic catalysis, such as time-consuming work-ups and enzyme inhibition, as well as difficult scale-up and process intensifications. Moreover, continuous flow biocatalysis provides access to practical, economical and more sustainable synthetic pathways, an important aspect for the future of pharmaceutical companies if they want to compete in the market while complying with European Medicines Agency (EMA), Food and Drug Administration (FDA) and green chemistry requirements. This review focuses on the most recent advances in the use of flow biocatalysis for the synthesis of active pharmaceutical ingredients (APIs), pharmaceuticals and natural products, and the advantages and limitations are discussed.

DegP protease is essential for tolerance to salt stress in the plant growth-promoting bacterium Gluconacetobacter diazotrophicus PAL5.

The use of plant growth-promoting bacteria represents an alternative to the massive use of mineral fertilizers in agriculture. However, some abiotic stresses commonly found in the environment, like salinity, can affect the efficiency of this approach. Here, we investigated the key mechanisms involved in the response of the plant growth-promoting bacterium Gluconacetobacter diazotrophicus to salt stress by using morphological and cell viability analyses, comparative proteomics, and reverse genetics. Our results revealed that the bacteria produce filamentous cells in response to salt at 100 mM and 150 mM NaCl. However, such a response was not observed at higher concentrations, where cell viability was severely affected. Proteomic analysis showed that salt stress modulates proteins involved in several pathways, including iron uptake, outer membrane efflux, osmotic adjustment, cell division and elongation, and protein transport and quality control. Proteomic data also revealed the repression of several extracytoplasmic proteins, especially those located at periplasm and outer membrane. The role of such pathways in the tolerance to salt stress was analyzed by the use of mutant defectives for Δtbdr (iron uptake), ΔmtlK and ΔotsA (compatible solutes synthesis), and ΔdegP (quality control of nascent extracytoplasmic proteins). ΔdegP presented the highest sensitivity to salt stress, Δtbdr, andΔmtlK also showed increased sensitivity, but ΔotsA was not affected. This is the first demonstration that DegP protein, a protease with minor chaperone activity, is essential for tolerance to salt stress in G. diazotrophicus. Our data contribute to a better understanding of the molecular bases that control the bacterial response/tolerance to salt stress, shedding light on quality control of nascent extracytoplasmic proteins.

Comparative proteomics reveals essential mechanisms for osmotolerance in Gluconacetobacter diazotrophicus.

Plant growth-promoting bacteria are a promising alternative to improve agricultural sustainability. Gluconacetobacter diazotrophicus is an osmotolerant bacterium able to colonize several plant species, including sugarcane, coffee, and rice. Despite its biotechnological potential, the mechanisms controlling such osmotolerance remain unclear. The present study investigated the key mechanisms of resistance to osmotic stress in G. diazotrophicus. The molecular pathways regulated by the stress were investigated by comparative proteomics, and proteins essential for resistance were identified by knock-out mutagenesis. Proteomics analysis led to identify regulatory pathways for osmotic adjustment, de novo saturated fatty acids biosynthesis, and uptake of nutrients. The mutagenesis analysis showed that the lack of AccC protein, an essential component of de novo fatty acid biosynthesis, severely affected G. diazotrophicus resistance to osmotic stress. Additionally, knock-out mutants for nutrients uptake (Δtbdr and ΔoprB) and compatible solutes synthesis (ΔmtlK and ΔotsA) became more sensitive to osmotic stress. Together, our results identified specific genes and mechanisms regulated by osmotic stress in an osmotolerant bacterium, shedding light on the essential role of cell envelope and extracytoplasmic proteins for osmotolerance.

Exercise Improves Lung Inflammation, but Not Lung Remodeling and Mechanics in a Model of Bleomycin-Induced Lung Fibrosis.

INTRODUCTION: Moderate aerobic exercise training accelerates the resolution of lung fibrosis in a model of bleomycin-induced pulmonary fibrosis. However, whether it can inhibit the development of lung fibrosis is unknown. MATERIALS AND METHODS: C57Bl/6 mice were distributed into four groups: Control (Co), Exercise (Exe), Bleomycin (Bleo), and Bleomycin+Exercise (Bleo+Exe). A single bleomycin dose (1.5 UI/kg) was administered orotracheally and treadmill exercise started in the same day, enduring for 4 weeks, 5x/week, 60 minutes/session, at moderate intensity. Lung mechanics, systemic and pulmonary inflammation, and lung remodeling were evaluated. Lung homogenates were used to evaluate the antioxidant status. RESULTS: Total cells, macrophages, lymphocytes, and neutrophils numbers, in agreement with IL-6 levels, were higher in the BAL and serum of Bleo group, compared to other groups. In addition, lung levels of LTB4 in Bleo were higher than other groups, whereas SOD activity and nitric oxide levels in exercised groups (Exe and Exe+Bleo) compared to the Bleo group. Lung GPX activity was lower in Bleo and Exe+Bleo groups compared to others. Exe and Exe+Bleo groups also showed higher IL-10 expression by lung macrophages than other groups, whereas TGF-ß expression was higher in Exe, Bleo, and Exe+Bleo groups compared to control. CCR7 expression was induced only in the Exe group. However, exercise did not improve lung remodeling and mechanics, or serum and pulmonary levels of VEGF, IGF-1, and TGF-ß. CONCLUSION: Aerobic exercise training initiated concomitantly with induction of pulmonary fibrosis reduces lung and systemic inflammation but fails to inhibit lung fibrosis and mechanics impairment.

An efficient approach for the synthesis of new (±)-coixspirolactams.

Coixspirolactams, spiro[oxindole-γ-lactones], are found in adlay seeds and exhibit anticancer activity. A novel synthetic methodology was developed to enable an easy access to (±)-coixspirolactam A and a large number of new coixspirolactams in excellent overall yields. The exquisite exploitation of formamide reactivity was essential for the construction of oxindole and lactone scaffolds.

Magnetic bio-nanocomposite catalysts of CoFe2O4/hydroxyapatite-lipase for enantioselective synthesis provide a framework for enzyme recovery and reuse.

Enzymatic catalysis is a sustainable alternative for cost-prohibitive catalysts based on noble metals and rare earths. Enzymes can catalyze selective reactions under mild conditions. Enzyme recovery after a reaction for its reuse is still a challenge for industrial application. Herein, a biocompatible magnetic nanocomposite is presented as alternative for enzyme stabilization and easy recovery. The magnetic core of CoFe2O4 provides capabilities for magnetic recovery. Two different functionalization methods based on adsorption of enzyme onto biocompatible hydroxyapatite (HAP) and through covalent bonding using a molecular spacer based on 3-Aminopropyl)triethoxysilane (APTES) have been evaluated. Both enzymatic bio-nanocomposites presented high selectivity for the transesterification reaction of racemic mixtures of (R,S)-1-phenylethanol, with complete conversion of (R)-1-phenylethanol enantiomer. Studies with different solvent and temperature had demonstrated high range of operation conditions due to enzyme stabilization provided by surface attachment. Meanwhile, magnetic properties allowed easy recovery through application of an external magnetic field for enzyme reuse. Results showed high stability of lipase covalently bond to CoFe2O4/HAP over several reaction cycles.

Green synthesis of Au decorated CoFe2O4 nanoparticles for catalytic reduction of 4-nitrophenol and dimethylphenylsilane oxidation.

Gold nanoparticles (Au NPs) have been widely employed in catalysis. Here, we report on the synthesis and catalytic evaluation of a hybrid material composed of Au NPs deposited at the surface of magnetic cobalt ferrite (CoFe2O4). Our reported approach enabled the synthesis of well-defined Au/CoFe2O4 NPs. The Au NPs were uniformly deposited at the surface of the support, displayed spherical shape, and were monodisperse in size. Their catalytic performance was investigated towards the reduction of 4-nitrophenol and the selective oxidation of dimethylphenylsilane to dimethylphenylsilanol. The material was active towards both transformations. In addition, the LSPR excitation in Au NPs could be employed to enhance the catalytic performance, which was demonstrated in the 4-nitrophenol reduction. Finally, the magnetic support allowed for the easy recovery and reuse of the Au/CoFe2O4 NPs. In this case, our data showed that no significant loss of performance took place even after 10 reaction cycles in the oxidation of dimethylphenylsilane to dimethylphenylsilanol. Overall, our results indicate that Au/CoFe2O4 are interesting systems for catalytic applications merging high performances, recovery and re-use, and enhancement of activities under solar light illumination.

Enzymatic reactions involving the heteroatoms from organic substrates.

Several enzymatic reactions of heteroatom-containing compounds have been explored as unnatural substrates. Considerable advances related to the search for efficient enzymatic systems able to support a broader substrate scope with high catalytic performance are described in the literature. These reports include mainly native and mutated enzymes and whole cells biocatalysis. Herein, we describe the historical background along with the progress of biocatalyzed reactions involving the heteroatom(S, Se, B, P and Si) from hetero-organic substrates.

Prevalence of lameness and hoof lesions in all year-round grazing cattle in Brazil.

Lameness is a growing concern to the dairy industry worldwide. However, little is known about lameness and its causes in grazing cattle, especially in tropical climates. This study aimed to assess the prevalence of hoof lesions and lameness in dairy herds of all year-round grazing cattle under tropical condition, and to identify the main lesions associated with lameness. We visited 48 farms located in the Minas Gerais state, Brazil, equally divided into four groups based on daily milk production. All lactating cows in the visited farms were locomotion scored, and a representative sample was randomly chosen for hoof inspection. Among the 2267 lactating cows evaluated, 16% were scored as lame and 7% as severely lame. Nearly all cows presented at least one type of hoof lesion, of which heel horn erosion (90%), white line fissure (50%), and digital dermatitis (33%) were the most prevalent. Heel horn erosion was present in all farms and digital dermatitis was present in 96% of the farms. Sole ulcer was observed in a single animal. Additionally, digital dermatitis and white line fissure were correlated to a 2.5 times increase in the odds of a poor mobility score. Collectively, our results demonstrate that digital dermatitis and white line fissure are the main concern and the biggest cause of lameness in grazing cattle under tropical conditions.

One pot biocatalytic synthesis of a biodegradable electroactive macromonomer based on 3,4-ethylenedioxytiophene and poly(l-lactic acid).

A novel electroactive macromonomer based on poly(l-lactic acid) (PLLA) with (3,4-ethylenedioxythiophene) (EDOT) functional end groups, was prepared by a traditional approach of organometallic polymerization with stannous octanoate [Sn(oct2)] and enzymatic polymerization using immobilized Candida antarctica Lipase B (CAL-B) and Amano lipase Pseudomonas cepacia(PS-IM), as catalysts. In the synthetic strategy, (2,3-dihydrothieno[3,4-b] dioxin-2-yl)methanol (EDOT-OH) was used to initiate the ring opening polymerization of lactide to yield PLLA with EDOT end group. All macromonomers (EDOT-PLLA) were characterized by 1H and 13C RMN, MALDI-TOF, GPC and EDX. Moreover, ICP-OES analysis showed the presence of Sn traces in the material synthesized by the traditional approach, but that pathway led to macromonomers with higher molecular weight while the enzymatic route led to completely metal-free macromonomers with medium and lower molecular weights. Also, electrochemical and chemical polymerization of EDOT-PLLA were tested showing that it is possible to prepare degradable conducting polymers based on poly(3,4-ethylenedioxythiphene) (PEDOT). The biocatalytic synthesis is a very promising and environmental friendly pathway for the preparation of biodegradable materials for short time applications.

Carbon dioxide/methanol conversion cycle based on cascade enzymatic reactions supported on superparamagnetic nanoparticles.

The conversion of carbon dioxide into important industrial feedstock is a subject of growing interest in modern society. A possible way to achieve this goal is by carrying out the CO2/methanol cascade reaction, allowing the recycle of CO2 using either chemical catalysts or enzymes. Efficient and selective reactions can be performed by enzymes; however, due to their low stability, immobilization protocols are required to improve their performance. The cascade reaction to reduce carbon dioxide into methanol has been explored by the authors, using, sequentially, alcohol dehydrogenase (ADH), formaldehyde dehydrogenase (FalDH), and formate dehydrogenase (FDH), powered by NAD+/NADH and glutamate dehydrogenase (GDH) as the co-enzyme regenerating system. All the enzymes have been immobilized on functionalized magnetite nanoparticles, and their reactions investigated separately in order to establish the best performance conditions. Although the stepwise scheme led to only 2.3% yield of methanol per NADH; in a batch system under CO2 pressure, the combination of the four immobilized enzymes increased the methanol yield by 64 fold. The studies indicated a successful regeneration of NADH in situ, envisaging a real possibility of using immobilized enzymes to perform the cascade CO2-methanol reaction.

Enzymatic reactions involving the heteroatoms from organic substrates

ABSTRACT Several enzymatic reactions of heteroatom-containing compounds have been explored as unnatural substrates. Considerable advances related to the search for efficient enzymatic systems able to support a broader substrate scope with high catalytic performance are described in the literature. These reports include mainly native and mutated enzymes and whole cells biocatalysis. Herein, we describe the historical background along with the progress of biocatalyzed reactions involving the heteroatom(S, Se, B, P and Si) from hetero-organic substrates.