RESUMO
Movement is a key means by which animals cope with variable environments. As they move, animals construct individual niches composed of the environmental conditions they experience. Niche axes may vary over time and covary with one another as animals make tradeoffs between competing needs. Seasonal migration is expected to produce substantial niche variation as animals move to keep pace with major life history phases and fluctuations in environmental conditions. Here, we apply a time-ordered principal component analysis to examine dynamic niche variance and covariance across the annual cycle for four species of migratory crane: common crane (Grus grus, n = 20), demoiselle crane (Anthropoides virgo, n = 66), black-necked crane (Grus nigricollis, n = 9), and white-naped crane (Grus vipio, n = 9). We consider four key niche components known to be important to aspects of crane natural history: enhanced vegetation index (resources availability), temperature (thermoregulation), crop proportion (preferred foraging habitat), and proximity to water (predator avoidance). All species showed a primary seasonal niche "rhythm" that dominated variance in niche components across the annual cycle. Secondary rhythms were linked to major species-specific life history phases (migration, breeding, and nonbreeding) as well as seasonal environmental patterns. Furthermore, we found that cranes' experiences of the environment emerge from time-dynamic tradeoffs among niche components. We suggest that our approach to estimating the environmental niche as a multidimensional and time-dynamical system of tradeoffs improves mechanistic understanding of organism-environment interactions.
Assuntos
Migração Animal , Aves , Ecossistema , Estações do Ano , Animais , Migração Animal/fisiologia , Aves/fisiologiaRESUMO
Paramagnetic defects of thin CaO(001) films grown on Mo(001) are characterized using electron paramagnetic resonance (EPR) spectroscopy under ultrahigh vacuum conditions. A variety of paramagnetic centers located in the volume of the films are identified whose speciation as well as relative abundance was found to depend on the growth rate of the films. Pristine films prepared at a lower growth rate exhibited a larger number and a different speciation of paramagnetic defects than films grown at a higher rate. Annealing of the films to 1030 K, which improves their long-range order, results in quenching of most of the paramagnetic species observed for the pristine film; however, films prepared at a lower growth rate exhibit new paramagnetic signals upon annealing, which are absent in films prepared at a higher growth rate. The signals can be assigned to paramagnetic Mo ions previously shown to diffuse into these films. These results indicate that the amount and speciation of the transition metal ions depend on the preparation conditions which in turn can also affect the surface chemistry of these systems.
RESUMO
INTRODUCTION: Recombinant coagulation factor VIII (FVIII) products are the standard of care for patients with haemophilia A. The development of modified FVIII products has provided benefit for patients but presented challenges for monitoring FVIII activity. AIM: This single-centre study evaluated the Roche FVIII one-stage clotting assay (OSA) in measuring FVIII activity in plasma samples spiked with seven FVIII products at clinically relevant concentrations. METHODS: FVIII-deficient plasma samples were spiked with two batches of recombinant FVIII products (octocog alfa, moroctocog alfa, simoctocog alfa, efmoroctocog alfa, damoctocog alfa pegol, rurioctocog alfa pegol, lonoctocog alfa) at 1-120 IU/dL FVIII activity, according to their labelled potency. Measurement was conducted on the cobas t 511/711 analysers using the Roche FVIII OSA and the Technoclone TECHNOCHROM FVIII:C chromogenic substrate assay (CSA). RESULTS: Using the OSA, FVIII activity was close to labelled potency for most analysed FVIII products including a recombinant FVIII Fc fusion protein. PEGylated FVIII product, damoctocog alfa pegol, was marginally above and single-chain product, lonoctocog alfa, below the predefined acceptance criteria: for FVIII activity < 25 IU/dL: ± 5 IU/dL; for FVIII activity ≥ 25 IU/dL: ± 20% (relative). The different principles of OSA and CSA led to discrepancies in the estimation of all analysed FVIII products. Additionally, in vitro recovery was increased at lower levels of FVIII activity using the OSA, whereas recovery was more consistent using the CSA. CONCLUSION: These data allow the interpretation of FVIII activity results for different FVIII products using the Roche FVIII OSA on the cobas t 511/711 analysers.
Assuntos
Hemofilia A , Hemostáticos , Testes de Coagulação Sanguínea , Fator VIII , Hemofilia A/tratamento farmacológico , HumanosRESUMO
Stereoselective methods for the synthesis of tetrahydro-ß-carbolines are of significant interest due to the broad spectrum of biological activity of the target molecules. In the plant kingdom, strictosidine synthases catalyze the C-C coupling through a Pictet-Spengler reaction of tryptamine and secologanin to exclusively form the (S)-configured tetrahydro-ß-carboline (S)-strictosidine. Investigating the biocatalytic Pictet-Spengler reaction of tryptamine with small-molecular-weight aliphatic aldehydes revealed that the strictosidine synthases give unexpectedly access to the (R)-configured product. Developing an efficient expression method for the enzyme allowed the preparative transformation of various aldehydes, giving the products with up to >98 % ee. With this tool in hand, a chemoenzymatic two-step synthesis of (R)-harmicine was achieved, giving (R)-harmicine in 67 % overall yield in optically pure form.
Assuntos
Carbolinas/metabolismo , Carbono-Nitrogênio Liases/metabolismo , Proteínas de Plantas/metabolismo , Biocatálise , Carbolinas/química , Catharanthus/enzimologia , Alcaloides Indólicos/química , Alcaloides Indólicos/metabolismo , Estereoisomerismo , Triptaminas/química , Triptaminas/metabolismoRESUMO
BACKGROUND: Transaminases have become a key tool in biocatalysis to introduce the amine functionality into a range of molecules like prochiral α-ketoacids and ketones. However, due to the necessity of shifting the equilibrium towards the product side (depending on the amine donor) an efficient amination system may require three enzymes. So far, this well-established transformation has mainly been performed in vitro by assembling all biocatalysts individually, which comes along with elaborate and costly preparation steps. We present the design and characterization of a flexible approach enabling a quick set-up of single-cell biocatalysts producing the desired enzymes. By choosing an appropriate co-expression strategy, a modular system was obtained, allowing for flexible plug-and-play combination of enzymes chosen from the toolbox of available transaminases and/or recycling enzymes tailored for the desired application. RESULTS: By using a two-plasmid strategy for the recycling enzyme and the transaminase together with chromosomal integration of an amino acid dehydrogenase, two enzyme modules could individually be selected and combined with specifically tailored E. coli strains. Various plug-and-play combinations of the enzymes led to the construction of a series of single-cell catalysts suitable for the amination of various types of substrates. On the one hand the fermentative amination of α-ketoacids coupled both with metabolic and non-metabolic cofactor regeneration was studied, giving access to the corresponding α-amino acids in up to 96% conversion. On the other hand, biocatalysts were employed in a non-metabolic, "in vitro-type" asymmetric reductive amination of the prochiral ketone 4-phenyl-2-butanone, yielding the amine in good conversion (77%) and excellent stereoselectivity (ee = 98%). CONCLUSIONS: The described modularized concept enables the construction of tailored single-cell catalysts which provide all required enzymes for asymmetric reductive amination in a flexible fashion, representing a more efficient approach for the production of chiral amines and amino acids.
Assuntos
Aminas/metabolismo , Proteínas de Bactérias/metabolismo , Escherichia coli/metabolismo , Cetoácidos/metabolismo , Cetonas/metabolismo , Transaminases/metabolismo , Aminação , Aminas/química , Proteínas de Bactérias/genética , Biocatálise , Isoleucina/metabolismo , Cetoácidos/química , Cetonas/química , Leucina/metabolismo , NAD/química , NAD/metabolismo , Plasmídeos , Estereoisomerismo , Especificidade por Substrato , Transaminases/genéticaRESUMO
The Friedel-Crafts acylation is commonly used for the synthesis of aryl ketones, and a biocatalytic version, which may benefit from the chemo- and regioselectivity of enzymes, has not yet been introduced. Described here is a bacterial acyltransferase which can catalyze Friedel-Crafts C-acylation of phenolic substrates in buffer without the need of CoA-activated reagents. Conversions reach up to >99 %, and various C- or O-acyl donors, such as DAPG or isopropenyl acetate, are accepted by this enzyme. Furthermore the enzyme enables a Fries rearrangement-like reaction of resorcinol derivatives. These findings open an avenue for the development of alternative and selective C-C bond formation methods.
Assuntos
Biocatálise , Acilação , Aciltransferases/metabolismo , Catálise , DNA Bacteriano/genética , Escherichia coli/crescimento & desenvolvimento , Cinética , Fenóis/metabolismo , Pseudomonas/enzimologia , Pseudomonas/genética , Especificidade por SubstratoRESUMO
Natural L-α-amino acids and L-norleucine were transformed to the corresponding α-hydroxy acids by formal biocatalytic inversion or retention of absolute configuration. The one-pot transformation was achieved by a concurrent oxidation reduction cascade in aqueous media. A representative panel of enantiopure (R)- and (S)-2-hydroxy acids possessing aliphatic, aromatic and heteroaromatic moieties were isolated in high yield (67-85 %) and enantiopure form (>99 % ee) without requiring chromatographic purification.
Assuntos
Aminoácidos/química , Hidroxiácidos/química , Estrutura Molecular , Oxirredução , EstereoisomerismoRESUMO
Time-synchronised data streams from bio-loggers are becoming increasingly important for analysing and interpreting intricate animal behaviour including split-second decision making, group dynamics, and collective responses to environmental conditions. With the increased use of AI-based approaches for behaviour classification, time synchronisation between recording systems is becoming an essential challenge. Current solutions in bio-logging rely on manually removing time errors during post processing, which is complex and typically does not achieve sub-second timing accuracies.We first introduce an error model to quantify time errors, then optimise three wireless methods for automated onboard time (re)synchronisation on bio-loggers (GPS, WiFi, proximity messages). The methods can be combined as required and, when coupled with a state-of-the-art real time clock, facilitate accurate time annotations for all types of bio-logging data without need for post processing. We analyse time accuracy of our optimised methods in stationary tests and in a case study on 99 Egyptian fruit bats (Rousettus aegyptiacus). Based on the results, we offer recommendations for projects that require high time synchrony.During stationary tests, our low power synchronisation methods achieved median time accuracies of 2.72 / 0.43 ms (GPS / WiFi), compared to UTC time, and relative median time accuracies of 5 ms between tags (wireless proximity messages). In our case study with bats, we achieved a median relative time accuracy of 40 ms between tags throughout the entire 10-day duration of tag deployment. Using only one automated resynchronisation per day, permanent UTC time accuracies of ≤ 185 ms can be guaranteed in 95% of cases over a wide temperature range between 0 and 50 °C. Accurate timekeeping required a minimal battery capacity, operating in the nano- to microwatt range.Time measurements on bio-loggers, similar to other forms of sensor-derived data, are prone to errors and so far received little scientific attention. Our combinable methods offer a means to quantify time errors and autonomously correct them at the source (i.e., on bio-loggers). This approach facilitates sub-second comparisons of simultaneously recorded time series data across multiple individuals and off-animal devices such as cameras or weather stations. Through automated resynchronisations on bio-loggers, long-term sub-second accurate timestamps become feasible, even for life-time studies on animals. We contend that our methods have potential to greatly enhance the quality of ecological data, thereby improving scientific conclusions.
RESUMO
Bio-telemetry from small tags attached to animals is one of the principal methods for studying the ecology and behaviour of wildlife. The field has constantly evolved over the last 80 years as technological improvement enabled a diversity of sensors to be integrated into the tags (e.g., GPS, accelerometers, etc.). However, retrieving data from tags on free-ranging animals remains a challenge since satellite and GSM networks are relatively expensive and or power hungry. Recently a new class of low-power communication networks have been developed and deployed worldwide to connect the internet of things (IoT). Here, we evaluated one of these, the Sigfox IoT network, for the potential as a real-time multi-sensor data retrieval and tag commanding system for studying fauna across a diversity of species and ecosystems. We tracked 312 individuals across 30 species (from 25 g bats to 3 t elephants) with seven different device concepts, resulting in more than 177,742 successful transmissions. We found a maximum line of sight communication distance of 280 km (on a flying cape vulture [Gyps coprotheres]), which sets a new documented record for animal-borne digital data transmission using terrestrial infrastructure. The average transmission success rate amounted to 68.3% (SD 22.1) on flying species and 54.1% (SD 27.4) on terrestrial species. In addition to GPS data, we also collected and transmitted data products from accelerometers, barometers, and thermometers. Further, we assessed the performance of Sigfox Atlas Native, a low-power method for positional estimates based on radio signal strengths and found a median accuracy of 12.89 km (MAD 5.17) on animals. We found that robust real-time communication (median message delay of 1.49 s), the extremely small size of the tags (starting at 1.28 g without GPS), and the low power demands (as low as 5.8 µAh per transmitted byte) unlock new possibilities for ecological data collection and global animal observation.
RESUMO
Previous research mostly focused on early parenting stress or postpartum symptoms of mental illness whereas the topic of a successful transition to motherhood and its long-term effects on parenting and child well-being remained more or less neglected. The present longitudinal study investigated whether a successful transition to motherhood influences emotionally warm parenting behavior, children's emotion regulation, and subjective life satisfaction. A successful transition to motherhood is feeling satisfied, self-efficient, and energetic in the maternal role during the first year after birth. Survey data from a large, nationally representative panel study with four measurement points across 11 years were analyzed using structural equation modeling (SEM). T1 corresponds to child's first year of life, at T2 children were around 3, at T3 the children were around 8, and at T4 children were around 12 years old. The study sample comprised 322 mother-child dyads. Mothers completed questionnaires to assess their early transition to motherhood (T1), children's emotion regulation (T1 and T2), and maternal warmth (T3). At age 12 (T4), children self-reported their life satisfaction. Results confirmed that a successful transition to motherhood had positive, long-term effects on maternal warmth and children's emotion regulation. Moreover, adapting optimally to motherhood had an indirect positive effect on children's subjective life satisfaction at age 12. Life satisfaction was in turn positively affected by maternal warmth and children's emotion regulation. The results highlight the importance of a successful transition to motherhood for parenting, children's emotion regulation, and life satisfaction. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
Assuntos
Regulação Emocional , Poder Familiar , Criança , Emoções , Feminino , Humanos , Estudos Longitudinais , Relações Mãe-Filho , MãesRESUMO
Background: Coagulation factor VIII (FVIII) inhibitor titer quantification is vital for optimizing care in people with hemophilia A. Objectives: This study analyzed the impact of the different kinetic profiles of four FVIII monoclonal antibodies on inhibitor titer quantification using the modified Nijmegen-Bethesda assay. Methods: Concentration-related and time-related profiles of FVIII antibodies (4A4, BO2C11, 2-54, ESH-8) were evaluated in vitro. FVIII residual activity was measured using a one-stage clotting assay and chromogenic substrate assay. Profiles of the FVIII antibodies were compared with the theoretical kinetic model: the ideal log (residual activity)-linear (inhibitor concentration) relationship. Different theoretical kinetic model-dependent and -independent criteria to calculate FVIII inhibitor titer were compared. Results: Factor VIII monoclonal antibodies had different concentration-related and time-related profiles, ideal for comparative analysis using the modified Nijmegen-Bethesda assay. The kinetic profile of 4A4 was similar to the theoretical kinetic model, while BO2C11 showed a steeper curve, and 2-54 and ESH-8 a flatter curve, than the model. In the modified Nijmegen-Bethesda assay, conversion of measured FVIII residual activities for different inhibitor dilutions into FVIII inhibitor titer is based on the theoretical kinetic model. Therefore, titer calculations for FVIII inhibitors that deviate from the model are prone to underestimation or overestimation. Calculating a theoretical dilution at 50% FVIII residual activity by sigmoidal regression reflecting different kinetic inhibition profiles can provide a more accurate titer result. Conclusion: Kinetic profiles of FVIII antibodies can deviate from the theoretical kinetic model in the modified Nijmegen-Bethesda assay, leading to differences in FVIII inhibitor titer quantification.
RESUMO
A recombinant enoate reductase from Gluconobacter oxydans was heterologously expressed, purified, characterised and applied in the asymmetric reduction of activated alkenes. In addition to the determination of the kinetic properties, the major focus of this work was to utilise the enzyme in the biotransformation of different interesting compounds such as 3,5,5-trimethyl-2-cyclohexen-1,4-dione (ketoisophorone) and (E/Z)-3,7-dimethyl-2,6-octadienal (citral). The reaction proceeded with excellent stereoselectivities (>99% ee) as well as absolute chemo- and regioselectivity, only the activated C=C bond of citral was reduced by the enoate reductase, while non-activated C=C bond and carbonyl moiety remained untouched. The described strategy can be used for the production of enantiomerically pure building blocks, which are difficult to prepare by chemical means. In general, the results show that the investigated enoate reductase is a promising catalyst for the use in asymmetric C=C bond reductions.
Assuntos
Alcenos/química , Alcenos/metabolismo , Proteínas de Bactérias/metabolismo , Gluconobacter oxydans/enzimologia , Oxirredutases/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Biocatálise , Biotransformação , Gluconobacter oxydans/química , Gluconobacter oxydans/genética , Gluconobacter oxydans/metabolismo , Cinética , Dados de Sequência Molecular , Oxirredução , Oxirredutases/química , Oxirredutases/genética , Alinhamento de Sequência , Estereoisomerismo , Especificidade por SubstratoRESUMO
A whole-cell catalyst using Escherichia coli BL21(DE3) as a host, co-expressing glycerol dehydrogenase (GlyDH) from Gluconobacter oxydans and glucose dehydrogenase (GDH) from Bacillus subtilis for cofactor regeneration, has been successfully constructed and used for the reduction of aliphatic aldehydes, such as hexanal or glyceraldehyde to the corresponding alcohols. This catalyst was characterized in terms of growth conditions, temperature and pH dependency, and regarding the influence of external cofactor and permeabilization. In the case of external cofactor addition we found a 4.6-fold increase in reaction rate caused by the addition of 1 mM NADP(+). Due to the fact that pH and temperature are also factors which may affect the reaction rate, their effect on the whole-cell catalyst was studied as well. Comparative studies between the whole-cell catalyst and the cell-free system were investigated. Furthermore, the successful application of the whole-cell catalyst in repetitive batch conversions could be demonstrated in the present study. Since the GlyDH was recently characterized and successfully applied in the kinetic resolution of racemic glyceraldehyde, we were now able to transfer and establish the process to a whole-cell system, which facilitated the access to L-glyceraldehyde in high enantioselectivity at 54% conversion. All in all, the whole-cell catalyst shows several advantages over the cell-free system like a higher thermal, a similar operational stability and the ability to recycle the catalyst without any loss-of-activity. The results obtained making the described whole-cell catalyst an improved catalyst for a more efficient production of enantiopure L-glyceraldehyde.
Assuntos
Bacillus subtilis/enzimologia , Escherichia coli/metabolismo , Gluconobacter oxydans/enzimologia , Glucose 1-Desidrogenase/metabolismo , Gliceraldeído/metabolismo , Desidrogenase do Álcool de Açúcar/metabolismo , Biotransformação , Escherichia coli/genética , Glucose 1-Desidrogenase/genética , Concentração de Íons de Hidrogênio , Cinética , NADP/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Desidrogenase do Álcool de Açúcar/genética , TemperaturaRESUMO
The cleavage of aryl methyl ethers is a common reaction in chemistry requiring rather harsh conditions; consequently, it is prone to undesired reactions and lacks regioselectivity. Nevertheless, O-demethylation of aryl methyl ethers is a tool to valorize natural and pharmaceutical compounds by deprotecting reactive hydroxyl moieties. Various oxidative enzymes are known to catalyze this reaction at the expense of molecular oxygen, which may lead in the case of phenols/catechols to undesired side reactions (e.g., oxidation, polymerization). Here an oxygen-independent demethylation via methyl transfer is presented employing a cobalamin-dependent veratrol-O-demethylase (vdmB). The biocatalytic demethylation transforms a variety of aryl methyl ethers with two functional methoxy moieties either in 1,2-position or in 1,3-position. Biocatalytic reactions enabled, for instance, the regioselective monodemethylation of substituted 3,4-dimethoxy phenol as well as the monodemethylation of 1,3,5-trimethoxybenzene. The methyltransferase vdmB was also successfully applied for the regioselective demethylation of natural compounds such as papaverine and rac-yatein. The approach presented here represents an alternative to chemical and enzymatic demethylation concepts and allows performing regioselective demethylation in the absence of oxygen under mild conditions, representing a valuable extension of the synthetic repertoire to modify pharmaceuticals and diversify natural products.
RESUMO
The acetic acid bacterium Gluconobacter oxydans has a high potential for oxidoreductases with a variety of different catalytic abilities. One putative oxidoreductase gene codes for an enzyme with a high similarity to the NADP+-dependent glycerol dehydrogenase (GlyDH) from Hypocrea jecorina. Due to this homology, the GlyDH (Gox1615) has been cloned, over-expressed in Escherichia coli, purified and characterised. Gox1615 shows an apparent native molecular mass of 39 kDa, which corresponds well to the mass of 37.213 kDa calculated from the primary structure. From HPLC measurements, a monomeric structure can be deduced. Kinetic parameters and the dependence of the activity on temperature and pH were determined. The enzyme shows a broad substrate spectrum in the reduction of different aliphatic, branched and aromatic aldehydes. Additionally, the enzyme has been shown to oxidize a variety of different alcohols. The highest activities were observed for the conversion of D-glyceraldehyde in the reductive and L-arabitol in the oxidative direction. Since high enantioselectivities were observed for the reduction of glyceraldehyde, the kinetic resolution of glyceraldehyde was investigated and found to yield enantiopure L-glyceraldehyde on preparative scale.
Assuntos
Gluconobacter oxydans/enzimologia , Gliceraldeído/metabolismo , Desidrogenase do Álcool de Açúcar/metabolismo , Sequência de Aminoácidos , Animais , Dados de Sequência Molecular , NADP/metabolismo , Oxirredução , Coelhos , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Homologia de Sequência de Aminoácidos , Especificidade por Substrato , Desidrogenase do Álcool de Açúcar/genética , Desidrogenase do Álcool de Açúcar/isolamento & purificaçãoRESUMO
Maternal well-being is assumed to be associated with well-being of individual family members, optimal parenting practices, and positive developmental outcomes for children. The objective of this study was to examine the interplay between maternal well-being, parent-child activities, and the well-being of 5- to 7-year-old children. In a sample of N = 291 mother-child dyads, maternal life satisfaction, the frequency of shared parent-child activities, as well as children's self-regulation, prosocial behavior, and receptive vocabulary were assessed using several methods. Data were collected in a special study of the Socio-Economic Panel Study (SOEP), a representative longitudinal survey of private households in Germany. Using structural equation modeling, significant positive direct and indirect relations between maternal life satisfaction, frequency of shared parent-child activities, children's self-regulation, prosocial behavior, and receptive vocabulary were found. The more satisfied the mother was, the more she shared activities with her child and the more the child acted prosocially. Furthermore, the higher the frequency of shared parent-child activities, the higher the child scored in all three analyzed indicators of children's well-being: self-regulation, prosocial behavior, and receptive vocabulary. The current study supports the assumption of maternal well-being as the basis of positive parenting practices and child well-being.
RESUMO
Organofluorine compounds have become important building blocks for a broad range of advanced materials, polymers, agrochemicals, and increasingly for pharmaceuticals. Despite tremendous progress within the area of fluorination chemistry, methods for the direct introduction of fluoroalkyl-groups into organic molecules without prefunctionalization are still highly desired. Here we present a concept for the introduction of the trifluoromethyl group into unprotected phenols by employing a biocatalyst (laccase), tBuOOH, and either the Langlois' reagent or Baran's zinc sulfinate. The method relies on the recombination of two radical species, namely, the phenol radical cation generated directly by the laccase and the CF3-radical. Various functional groups such as ketone, ester, aldehyde, ether and nitrile are tolerated. This laccase-catalysed trifluoromethylation proceeds under mild conditions and allows accessing trifluoromethyl-substituted phenols that were not available by classical methods.
RESUMO
Cobalamine cofactors (vitamin B12) are complex organometallic molecules that are crucial for the activity of a variety of different interesting enzymes such as isomerases, methyltransferases, and dehalogenases. Developments in understanding the structure, mechanism, and role in nature of methylcobalamin-dependent methyltransferases make them excellent candidates for biotechnological applications such as biocatalytic dealkylation.
Assuntos
Biotecnologia , Metiltransferases , Vitamina B 12 , MetilaçãoRESUMO
Combinatorial assembly and variation of promoters on a single expression plasmid allowed the balance of the catalytic steps of a three enzyme (l-AAD, HIC, FDH) cascade in E. coli. The designer cell catalyst quantitatively transformed l-amino acids to the corresponding optically pure (R)- and (S)-α-hydroxy acids at up to 200 mM substrate concentration.
Assuntos
Aminoácidos/metabolismo , Hidroxiácidos/química , Hidroxiácidos/metabolismo , Biologia Sintética , Biocatálise , Escherichia coli/genética , Escherichia coli/metabolismo , Plasmídeos/genética , EstereoisomerismoRESUMO
An efficient and sustainable biocatalytic route for the synthesis of important 17-α-amino steroids has been developed using an ω-transaminase variant from Arthrobacter sp. Optimisation of the reaction conditions facilitated the synthesis of these valuable synthons on a preparative scale, affording excellent isolated yields and stereocontrol.