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1.
Clin Exp Rheumatol ; 41(4): 943-947, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36995315

RESUMO

OBJECTIVES: Although management of vasculitis has evolved over the last decades, glucocorticoids (GC) have remained the cornerstone of treatment. The side effects (SE) of GC are well known by the clinicians; their importance for patients with vasculitis has not been investigated as extensively as in other rheumatological conditions. METHODS: An online questionnaire surveyed between April 29th. to July 31st, 2022 with Vasculitis Foundation Canada about the patient experience and SE of prednisone. The survey included 5 questions about prednisone dose and duration, 21 about specific SE (with a rating of 1-10, and one question each on worst prednisone, and worst vasculitis, SE), and four other questions about knowledge and perception of possible alternatives to prednisone (namely, avacopan). RESULTS: A total of 97 patients (53 GPA/MPA, 44 other vasculitides) completed the survey. Their mean duration of GC use was 62.7±83.7 months, and 49.5% of patients were still on GC (daily dose, 8.4±6.2mg). All the patients reported ≥1 GC-related SE, and 67.0% reported ≥11/19 pre-specified SE of interest. Among ranked SEs, acne was the lowest score, whereas moon face/torso hump had the highest score, just above weight gain, insomnia and decreased quality of life. Around half of the GPA/MPA patients and one-third of the others had heard about avacopan, and 68% of patients (similarly in both groups) stated they would prefer being the first to take a very new medication, such as avacopan, instead of prednisone. CONCLUSIONS: Ranking given to some GC-related SEs may differ between patients and physicians. GC toxicity/SE indexes should reflect this difference.


Assuntos
Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Vasculite , Humanos , Prednisona/efeitos adversos , Qualidade de Vida , Canadá , Glucocorticoides/efeitos adversos , Vasculite/induzido quimicamente , Vasculite/tratamento farmacológico , Inquéritos e Questionários
2.
MMWR Morb Mortal Wkly Rep ; 71(49): 1547-1549, 2022 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-36480462

RESUMO

In late August 2021, a boy aged 7 years was bitten by a bat while he was playing outside his apartment home in Medina County, Texas. He informed his parents; however, no rabies postexposure prophylaxis (PEP) was sought because there were no visible bite marks, and the family was unaware that contact with a bat, including in the absence of visible bite marks, might cause rabies. Approximately 2 months later, the child was hospitalized for altered mental status, seizures, and hypersalivation and ultimately received a diagnosis of rabies. Experimental therapies were attempted; however, the child died 22 days after symptom onset. Fifty-seven persons who met criteria for suspected or known exposure to infectious secretions in this case were advised to consult with a medical provider about the need for rabies PEP in accordance with Advisory Committee on Immunization Practices (ACIP) guidelines (1). Rabies, an acute, progressive neuroencephalitis, is nearly always fatal. Although dogs are the most common source of human rabies deaths worldwide and account for an estimated 59,000 annual cases of human rabies globally (2), bats are the most common source of domestically acquired rabies in the United States and have been implicated in 31 (81.6%) of 38 human infections since 2000 (3). Attempts to prevent death or poor neurologic outcomes once rabies symptoms develop have been largely unsuccessful (4). Administration of rabies PEP, comprising rabies immunoglobulin and a series of doses of rabies vaccine, is critical to preventing rabies after an exposure; enhanced public education about the risk posed by bats, and the availability of PEP to prevent rabies, is needed.


Assuntos
Pais , Criança , Humanos , Cães , Animais , Texas/epidemiologia
3.
Nano Lett ; 22(13): 5151-5157, 2022 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-35776079

RESUMO

Metasurfaces, artificially engineered surfaces comprised of subwavelength resonators, show promise for realizing a new generation of optical materials and devices. However, current metasurface architectures suffer from environmental degradation, a limited spectral range, and a lack of scalability. Here, we demonstrate a novel large-area embedded metasurface architecture that is environmentally robust and capable of a spectrally selective absorption of greater than 80% spanning from 330 to 2740 nm. These fully encapsulated metasurfaces leverage the capabilities of colloidal plasmonic nanoparticles with various crystallinities, materials, shapes, and sizes to access a larger spectral range and allow for control of nanoscale spatial losses and subsequent heat generation within the constituent elements of the metasurface. Through the selection of material, particle size, and shape, these metasurfaces can be designed across the ultraviolet (UV) to short-wave infrared (SWIR) region for various hot-electron, photodetection, photocatalysis, and photothermal processes.

4.
Nano Lett ; 22(9): 3525-3531, 2022 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-35472261

RESUMO

Actively tunable optical materials integrated with engineered subwavelength structures could enable novel optoelectronic devices, including reconfigurable light sources and tunable on-chip spectral filters. The phase-change material vanadium dioxide (VO2) provides a promising solid-state solution for dynamic tuning; however, previous demonstrations have been limited to thicker and often rough VO2 films or require a lattice-matched substrate for growth. Here, sub-10-nm-thick VO2 films are realized by atomic layer deposition (ALD) and integrated with plasmonic nanogap cavities to demonstrate tunable, spectrally selective absorption across 1200 nm in the near-infrared (NIR). Upon inducing the phase transition via heating, the absorption resonance is blue-shifted by as much as 60 nm. This process is reversible upon cooling and repeatable over more than ten temperature cycles. Dynamic, ultrathin VO2 films deposited by ALD, as demonstrated here, open up new potential architectures and applications where VO2 can be utilized to provide reconfigurability including three-dimensional, flexible and large-area structures.

5.
Foods ; 11(3)2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-35159579

RESUMO

The sustainable extraction of secondary metabolites from Brassica agro-industrial by-products often involves the use of high concentrations of ethanol, and/or high temperatures, which tends to decrease the efficiency of protein extraction (yield, profile, etc.). To understand the limits of the combination of these two extraction processes, aqueous ethanol extraction of secondary metabolites (e.g., phenolic compounds and glucosinolates) from Brassica carinata defatted meal was optimized using Response Surface Methodology. The validated models predicted that aqueous ethanol extraction of defatted Carinata meal, with a low aqueous EtOH concentration (22% EtOH) at moderate Te (50 °C), enables the efficient recovery of secondary metabolites (sinapine = 9.12 ± 0.05 mg/gDM, sinigrin = 86.54 ± 3.18 µmol/gDM) while maintaining good protein extractability (59.8 ± 2.1%) from successive alkaline extractions. The evaluation of functional properties of the resulting protein isolates revealed that aqueous extraction, under optimized conditions, improves foaming activity while preserving emulsion ability.

6.
Front Chem ; 9: 664602, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34055737

RESUMO

Sinapic acid (SinA) and corresponding esters are secondary metabolites abundantly found in plants of Brassica family. Belonging to the family of p-hydroxycinnamic acids, SinA and its esters analogues are present in different plant parts and involved in multiple biological processes in planta. Moreover, these metabolites are also found in relatively large quantities in agro-industrial wastes. Nowadays, these metabolites are increasingly drawing attention due to their bioactivities which include antioxidant, anti-microbial, anti-cancer and UV filtering activities. As a result, these metabolites find applications in pharmaceutical, cosmetic and food industries. In this context, this article reviews innate occurrence, biosynthesis, accessibility via chemical synthesis or direct extraction from agro-industrial wastes. Biological activities of SinA and its main corresponding esters will also be discussed.

7.
Molecules ; 25(19)2020 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-33022970

RESUMO

Glucosinolates (GSLs) are secondary plant metabolites abundantly found in plant order Brassicales. GSLs are constituted by an S-ß-d-glucopyrano unit anomerically connected to O-sulfated (Z)-thiohydroximate moiety. The side-chain of the O-sulfate thiohydroximate moiety, which is derived from a different amino acid, contributes to the diversity of natural GSL, with more than 130 structures identified and validated to this day. Both the structural diversity of GSL and their biological implication in plants have been biochemically studied. Although chemical syntheses of GSL have been devised to give access to these secondary metabolites, direct extraction from biomass remains the conventional method to isolate natural GSL. While intact GSLs are biologically inactive, various products, including isothiocyanates, nitriles, epithionitriles, and cyanides obtained through their hydrolysis of GSLs, exhibit many different biological activities, among which several therapeutic benefits have been suggested. This article reviews natural occurrence, accessibility via chemical, synthetic biochemical pathways of GSL, and the current methodology of extraction, purification, and characterization. Structural information, including the most recent classification of GSL, and their stability and storage conditions will also be discussed. The biological perspective will also be explored to demonstrate the importance of these prominent metabolites.


Assuntos
Glucosinolatos/química , Glucosinolatos/isolamento & purificação , Domínio Catalítico , Glucosinolatos/biossíntese , Glucosinolatos/farmacologia , Glicosídeo Hidrolases/metabolismo , Hidrólise , Plantas/metabolismo , Soluções
8.
Enzyme Microb Technol ; 137: 109515, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32423667

RESUMO

Serine palmitoyltransferase (SPTase), the first enzyme of the sphingolipid biosynthesis pathway, produces 3-ketodihydrosphingosine by a Claisen-like condensation/decarboxylation reaction of l-Ser and palmitoyl-CoA (n-C16-CoA). Previous structural analysis of Sphingomonas paucimobilis SPTase (SpSPTase) revealed a dynamic active site loop (RPPATP; amino acids 378-383) in which R378 (underlined) forms a salt bridge with the carboxylic acid group of the PLP : l-Ser external aldimine. We hypothesized that this interaction might play a key role in acyl group substrate selectivity and therefore performed site-saturation mutagenesis at position 378 based on semi-rational design to expand tolerance for shorter acyl-CoA's. The resulting library was initially screened for the reaction between l-Ser and dodecanoyl-CoA (n-C12-CoA). The most interesting mutant (R378 K) was then purified and compared to wild-type SpSPTase against a panel of acyl-CoA's. These data showed that the R378 K substitution shifted the acyl group preference to shorter chain lengths, opening the possibility of using this and other engineered variants for biocatalytic C-C bond-forming reactions.


Assuntos
Acil Coenzima A/metabolismo , Engenharia Metabólica/métodos , Serina C-Palmitoiltransferase/genética , Serina C-Palmitoiltransferase/metabolismo , Sphingomonas/enzimologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Domínio Catalítico , Ensaios de Triagem em Larga Escala , Modelos Moleculares , Esfingosina/análogos & derivados , Esfingosina/metabolismo , Especificidade por Substrato
9.
Nat Mater ; 19(2): 158-162, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31768011

RESUMO

Thermal detectors, such as bolometric, pyroelectric and thermoelectric devices, are uniquely capable of sensing incident radiation for any electromagnetic frequency; however, the response times of practical devices are typically on the millisecond scale1-7. By integrating a plasmonic metasurface with an aluminium nitride pyroelectric thin film, we demonstrate spectrally selective, room-temperature pyroelectric detectors from 660-2,000 nm with an instrument-limited 1.7 ns full width at half maximum and 700 ps rise time. Heat generated from light absorption diffuses through the subwavelength absorber into the pyroelectric film producing responsivities up to 0.18 V W-1 due to the temperature-dependent spontaneous polarization of the pyroelectric films. Moreover, finite-element simulations reveal the possibility of reaching a 25 ps full width at half maximum and 6 ps rise time rivalling that of semiconductor photodiodes8. This design approach has the potential to realize large-area, inexpensive gigahertz pyroelectric detectors for wavelength-specific detection from the ultraviolet to short-wave infrared or beyond for, for example, high-speed hyperspectral imaging.

10.
Enzyme Microb Technol ; 128: 67-71, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31186112

RESUMO

The substrate selectivity of the Trp416Gly mutant of Methanothermobacter thermautotrophicus acetyl-CoA synthetase (Trp416Gly MT-ACS1) was explored. The goal was to identify its substrate range, particularly for functionalized carboxylic acid substrates that would allow post-synthesis functionalization of CoA thioesters or downstream products using metathesis or Click chemistry. Relative activities were determined by in situ formation of acyl-hydroxamate iron (III) complexes. Trp416Gly MT-ACS1 showed good activities for saturated straight chain carboxylic acids from C2 to C8, for ω-alkenyl straight chain carboxylic acids from C4 to C7 and for ω-alkynyl straight chain carboxylic acids from C5 to C7. Carboxylic acids showing ≥20% conversion in screening reactions were used in preparative conversions that completely consumed the added CoASH.


Assuntos
Acetato-CoA Ligase/metabolismo , Substituição de Aminoácidos , Methanobacteriaceae/enzimologia , Proteínas Mutantes/metabolismo , Acetato-CoA Ligase/genética , Ácidos Carboxílicos/metabolismo , Proteínas Mutantes/genética , Mutação Puntual , Especificidade por Substrato
11.
Plant J ; 99(1): 23-40, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30746832

RESUMO

Cereal yields decrease when grain fill proceeds under conditions of prolonged, moderately elevated temperatures. Endosperm-endogenous processes alter both rate and duration of dry weight gain, but underlying mechanisms remain unclear. Heat effects could be mediated by either abnormal, premature cessation of storage compound deposition or accelerated implementation of normal development. This study used controlled environments to isolate temperature as the sole environmental variable during Zea mays kernel-fill, from 12 days after pollination to maturity. Plants subjected to elevated day, elevated night temperatures (38°C day, 28°C night (38/28°C])) or elevated day, normal night (38/17°C), were compared with those from controls grown under normal day and night conditions (28/17°C). Progression of change over time in endosperm tissue was followed to dissect contributions at multiple levels, including transcriptome, metabolome, enzyme activities, product accumulation, and tissue ultrastructure. Integrated analyses indicated that the normal developmental program of endosperm is fully executed under prolonged high-temperature conditions, but at a faster rate. Accelerated development was observed when both day and night temperatures were elevated, but not when daytime temperature alone was increased. Although transcripts for most components of glycolysis and respiration were either upregulated or minimally affected, elevated temperatures decreased abundance of mRNAs related to biosynthesis of starch and storage proteins. Further analysis of 20 central-metabolic enzymes revealed six activities that were reduced under high-temperature conditions, indicating candidate roles in the observed reduction of grain dry weight. Nonetheless, a striking overall resilience of grain filling in the face of elevated temperatures can be attributed to acceleration of normal endosperm development.


Assuntos
Endosperma/metabolismo , Zea mays/metabolismo , Grão Comestível/genética , Grão Comestível/metabolismo , Grão Comestível/fisiologia , Endosperma/genética , Endosperma/fisiologia , RNA Mensageiro/metabolismo , RNA de Plantas/metabolismo , Temperatura , Zea mays/genética , Zea mays/fisiologia
12.
Enzyme Microb Technol ; 119: 1-9, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30243380

RESUMO

Three threonine aldolases (TAs) were cloned and overexpressed in Escherichia coli (Aeromonas jandaeil-allo-threonine aldolase, E. colil-threonine aldolase and Thermotoga maritimal-allo-threonine aldolase). A Design of Experiments strategy was used to identify optimal reaction conditions for each enzyme. These conditions were used to characterize the substrate- and stereoselectivity of each TA toward a panel of aldehyde acceptors. In general, the A. jandaei TA performed best, and six representative conversions were scaled up 10-fold in order to develop downstream steps for product isolation. One key improvement was to treat the crude reaction product with Bacillus subtilis glycine oxidase, which eliminated residual starting material and significantly simplified product isolation. NMR studies were used to identify the major and minor diastereomers from the preparative-scale reactions and the absolute configurations for three representative cases.


Assuntos
Aeromonas/enzimologia , Escherichia coli/enzimologia , Glicina Hidroximetiltransferase/metabolismo , Thermotoga maritima/enzimologia , Aldeídos/metabolismo , Aminoácido Oxirredutases/genética , Aminoácido Oxirredutases/metabolismo , Bacillus subtilis/enzimologia , Glicina Hidroximetiltransferase/genética , Glicina Hidroximetiltransferase/isolamento & purificação , Especificidade por Substrato , Treonina/metabolismo
13.
Nano Lett ; 18(2): 853-858, 2018 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-29284087

RESUMO

Active plasmonic nanostructures with tunable resonances promise to enable smart materials with multiple functionalities, on-chip spectral-based imaging and low-power optoelectronic devices. A variety of tunable materials have been integrated with plasmonic structures, however, the tuning range in the visible regime has been limited to less than the line width of the resonance resulting in small on/off ratios. Here we demonstrate dynamic tuning of plasmon resonances up to 71 nm through multiple cycles by incorporating photochromic molecules into plasmonic nanopatch antennas. Exposure to ultraviolet (UV) light switches the molecules into a photoactive state enabling dynamic control with on/off ratios up to 9.2 dB and a tuning figure of merit up to 1.43, defined as the ratio between the spectral shift and the initial line width of the plasmonic resonance. Moreover, the physical mechanisms underlying the large spectral shifts are elucidated by studying over 40 individual nanoantennas with fundamental resonances from 550 to 720 nm revealing good agreement with finite-element simulations.

14.
Proc Natl Acad Sci U S A ; 115(1): E24-E33, 2018 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-29255019

RESUMO

Maize opaque2 (o2) mutations are beneficial for endosperm nutritional quality but cause negative pleiotropic effects for reasons that are not fully understood. Direct targets of the bZIP transcriptional regulator encoded by o2 include pdk1 and pdk2 that specify pyruvate phosphate dikinase (PPDK). This enzyme reversibly converts AMP, pyrophosphate, and phosphoenolpyruvate to ATP, orthophosphate, and pyruvate and provides diverse functions in plants. This study addressed PPDK function in maize starchy endosperm where it is highly abundant during grain fill. pdk1 and pdk2 were inactivated individually by transposon insertions, and both genes were simultaneously targeted by endosperm-specific RNAi. pdk2 accounts for the large majority of endosperm PPDK, whereas pdk1 specifies the abundant mesophyll form. The pdk1- mutation is seedling-lethal, indicating that C4 photosynthesis is essential in maize. RNAi expression in transgenic endosperm eliminated detectable PPDK protein and enzyme activity. Transgenic kernels weighed the same on average as nontransgenic siblings, with normal endosperm starch and total N contents, indicating that PPDK is not required for net storage compound synthesis. An opaque phenotype resulted from complete PPDK knockout, including loss of vitreous endosperm character similar to the phenotype conditioned by o2-. Concentrations of multiple glycolytic intermediates were elevated in transgenic endosperm, energy charge was altered, and starch granules were more numerous but smaller on average than normal. The data indicate that PPDK modulates endosperm metabolism, potentially through reversible adjustments to energy charge, and reveal that o2- mutations can affect the opaque phenotype through regulation of PPDK in addition to their previously demonstrated effects on storage protein gene expression.


Assuntos
Endosperma/enzimologia , Metabolismo Energético/fisiologia , Proteínas de Plantas/metabolismo , Piruvato Ortofosfato Diquinase/metabolismo , Zea mays/enzimologia , Endosperma/genética , Mutação , Proteínas de Plantas/genética , Piruvato Ortofosfato Diquinase/genética , Amido/biossíntese , Amido/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Zea mays/genética
15.
Nat Commun ; 8(1): 2135, 2017 12 12.
Artigo em Inglês | MEDLINE | ID: mdl-29233993

RESUMO

The originally published version of this Article contained an error in Equation 1. The two ℏ terms were missing from this equation. This has now been corrected in the PDF and HTML versions of the Article.

16.
Nat Commun ; 8(1): 986, 2017 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-29042536

RESUMO

The creation of energetic electrons through plasmon excitation of nanostructures before thermalization has been proposed for a wide number of applications in optical energy conversion and ultrafast nanophotonics. However, the use of "nonthermal" electrons is primarily limited by both a low generation efficiency and their ultrafast decay. We report experimental and theoretical results on the use of broadband plasmonic nanopatch metasurfaces comprising a gold substrate coupled to silver nanocubes that produce large concentrations of hot electrons, which we measure using transient absorption spectroscopy. We find evidence for three subpopulations of nonthermal carriers, which we propose arise from anisotropic electron-electron scattering within sp-bands near the Fermi surface. The bimetallic character of the metasurface strongly impacts the physics, with dissipation occurring primarily in the gold, whereas the quantum process of hot electron generation takes place in both components. Our calculations show that the choice of geometry and materials is crucial for producing strong ultrafast nonthermal electron components.The creation of energetic electrons through plasmon excitation has implications in optical energy conversion and ultrafast nanophotonics. Here, the authors find evidence for three subpopulations of nonthermal carriers which arise from anisotropic electron-electron scattering near the Fermi surface.

17.
Adv Mater ; 29(6)2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27966235

RESUMO

Multispectral colloidal metasurfaces are fabricated that exhibit greater than 85% absorption and ≈100 nm linewidths by patterning film-coupled nanocubes in pixels using a fusion of bottom-up and top-down fabrication techniques over wafer-scale areas. With this technique, the authors realize a multispectral pixel array consisting of six resonances between 580 and 1125 nm and reconstruct an RGB image with 9261 color combinations.

18.
Biomacromolecules ; 16(8): 2374-81, 2015 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-26151628

RESUMO

Polymers of similar molecular weights and chemical constitution but varying in their macromolecular architectures were conjugated to osteoprotegerin (OPG) to determine the effect of polymer topology on protein activity in vitro and in vivo. OPG is a protein that inhibits bone resorption by preventing the formation of mature osteoclasts from the osteoclast precursor cell. Accelerated bone loss disorders, such as osteoporosis, rheumatoid arthritis, and metastatic bone disease, occur as a result of increased osteoclastogenesis, leading to the severe weakening of the bone. OPG has shown promise as a treatment in bone disorders; however, it is rapidly cleared from circulation through rapid liver uptake, and frequent, high doses of the protein are necessary to achieve a therapeutic benefit. We aimed to improve the effectiveness of OPG by creating OPG-polymer bioconjugates, employing reversible addition-fragmentation chain transfer polymerization to create well-defined polymers with branching densities varying from linear, loosely branched to densely branched. Polymers with each of these architectures were conjugated to OPG using a "grafting-to" approach, and the bioconjugates were characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The OPG-polymer bioconjugates showed retention of activity in vitro against osteoclasts, and each bioconjugate was shown to be nontoxic. Preliminary in vivo studies further supported the nontoxic characteristics of the bioconjugates, and measurement of the bone mineral density in rats 7 days post-treatment via peripheral quantitative computed tomography suggested a slight increase in bone mineral density after administration of the loosely branched OPG-polymer bioconjugate.


Assuntos
Artrite Reumatoide/tratamento farmacológico , Reabsorção Óssea/tratamento farmacológico , Osteoporose/tratamento farmacológico , Osteoprotegerina/química , Animais , Artrite Reumatoide/patologia , Densidade Óssea/efeitos dos fármacos , Reabsorção Óssea/patologia , Humanos , Osteoclastos/efeitos dos fármacos , Osteoclastos/patologia , Osteoporose/patologia , Osteoprotegerina/administração & dosagem , Polímeros/administração & dosagem , Polímeros/química , Ratos
19.
Biotechnol Adv ; 33(5): 624-31, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25940546

RESUMO

In the 20 years since Massey's initial report in 1995, interest in using alkene reductases to prepare chiral intermediates for synthesis has grown rapidly. While native alkene reductases often show very high stereoselectivities toward favorable substrates, these enzymes have somewhat size-restricted active sites that limit their substrate ranges to small alkenes. In addition, most alkene reductases have the same stereoselectivities, which makes it difficult to access the "other" product enantiomers. Protein engineering strategies have been used to address both of these issues and good progress has been made in several cases. This review summarizes published examples through late 2014 and focuses on studies of six enzymes: Saccharomyces pastorianus OYE 1, tomato OPR1, Zymomonas mobilis NCR, Enterobacter cloacae PB2 PETN reductase, Bacillus subtilis YqjM and Pichia stipitis OYE 2.6.


Assuntos
Biotecnologia , NADPH Desidrogenase , Engenharia de Proteínas
20.
Arch Biochem Biophys ; 568: 28-37, 2015 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-25600571

RESUMO

Iterative saturation mutagenesis (ISM) has been used to improve the thermostability of maize endosperm ADP-glucose pyrophosphorylase (AGPase), a highly-regulated, rate-limiting and temperature-sensitive enzyme essential for starch biosynthesis. The thermo-sensitivity of heterotetrameric AGPase has been linked to grain loss in cereals and improving this property might therefore have direct impacts on grain yield. Nine amino acids were selected for site-saturation mutagenesis on the basis of elevated B-factors in the crystal structure of the closest available homolog (a small subunit homotetramer of potato AGPase). After each round of mutagenesis, iodine staining and antibody capture activity assays at varying temperatures were used to select the optimum positions and amino acid changes for the next rounds of mutagenesis. After three iterations, the signals from whole-colony iodine staining were saturated and a heat stable AGPase variant was obtained. Kinetic studies of the heat stable mutant showed that it also had an unexpected increased affinity for the activator, 3-PGA. This is particularly valuable as both the temperature stability and allosteric properties of AGPase significantly influence grain yield.


Assuntos
Endosperma/enzimologia , Estabilidade Enzimática , Glucose-1-Fosfato Adenililtransferase/genética , Glucose-1-Fosfato Adenililtransferase/metabolismo , Zea mays/enzimologia , Cristalografia por Raios X , Endosperma/química , Endosperma/genética , Regulação da Expressão Gênica de Plantas , Glucose-1-Fosfato Adenililtransferase/química , Temperatura Alta , Cinética , Modelos Moleculares , Mutagênese Sítio-Dirigida , Zea mays/química , Zea mays/genética
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