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1.
ACS Synth Biol ; 9(10): 2639-2647, 2020 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-33025786

RESUMO

Synthetic protein-level circuits offer an extra layer of cellular control on top of conventional gene-level circuits. Here, we describe a technology that allows conditional protein rescue (CPR) from proteasomal degradation using different protein inputs as masking agents. A target protein is fused to a degron tag and an affinity sensor domain. The use of nanobodies as the sensor domain offers a generalizable strategy to execute a wide range of protein-level circuits with ease. The utility of this new strategy was successfully demonstrated to distinguish cancer cells out of a healthy population using the HPV-specific E7 protein as a cellular marker. Because CPR can be programmed to execute more complex Boolean logic designs using cell-specific proteomes, this platform offers a highly modular and scalable framework for a wide range of applications based on synthetic protein circuits.


Assuntos
Complexo de Endopeptidases do Proteassoma/metabolismo , Engenharia de Proteínas/métodos , Proteínas/genética , Proteínas/imunologia , Proteólise , Anticorpos de Domínio Único/imunologia , Antígenos/imunologia , Citosina Desaminase/metabolismo , Redes Reguladoras de Genes , Células HEK293 , Células HeLa , Humanos , Proteínas E7 de Papillomavirus/metabolismo , Plasmídeos/genética , Pró-Fármacos/metabolismo , Transfecção , Leveduras/enzimologia
2.
Bioorg Chem ; 100: 103919, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32417524

RESUMO

Chemical investigation of the aerial parts of Cnidoscolus spinosus resulted in the isolation of relatively infrequent hopane-type triterpenes, 3ß-acetoxy-hop-22(29)-ene (1), first reported here as natural product, together with 3-oxo-hop-22(29)-ene (2), and 3ß-hydroxy-hop-22(29)-ene (3). ß-Amyrin palmitate and three phytosterols were also characterized. The structures of the compounds were established using spectroscopic methods, and those of 1 and 2 were confirmed by crystallographic analysis. Selected biological activities for the isolated hopane-type triterpenes were tested through a series of assays for determining the cytotoxic, anti-inflammatory, α-glucosidase inhibition and antiparasitic activities. Compounds 1-3 did not show cytotoxic activity, compound 1 displayed an important inhibitory effect in the mouse ear induced inflammation assay, and significantly inhibited the yeast α-glucosidase activity in vitro and in silico. Additionally, compounds 2 and 3 showed marginal activities against Trypanosoma cruzi and Leishmania mexicana. Therefore, the bioactivities of hopane-type triterpenes deserve further investigation, particularly their anti-inflammatory properties.


Assuntos
Anti-Inflamatórios/química , Anti-Inflamatórios/farmacologia , Euphorbiaceae/química , Triterpenos/química , Triterpenos/farmacologia , Animais , Anti-Inflamatórios/isolamento & purificação , Antiparasitários/química , Antiparasitários/farmacologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Inibidores de Glicosídeo Hidrolases/química , Inibidores de Glicosídeo Hidrolases/farmacologia , Humanos , Masculino , Camundongos , Simulação de Acoplamento Molecular , Triterpenos/isolamento & purificação , Leveduras/enzimologia , alfa-Glucosidases/metabolismo
3.
Biotechnol Appl Biochem ; 67(5): 714-722, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31498481

RESUMO

Oil palm empty fruit bunch (OPEFB) is a lignocellulosic biomass generated in palm oil mills. It is a sustainable resource for fuels and chemicals. In this study, OPEFB was converted to ethanol by an integrative OPEFB conversion process including dilute alkaline pretreatment, cellulolytic enzyme production, separate OPEFB hydrolysis, and cofermentation using a hybrid xylose-fermenting yeast. OPEFB was pretreated using 1% (w/v) NaOH solution followed by 1% (v/v) H2 O2 . Further, cellulolytic enzymes were produced by submerged fermentation using Trichoderma reesei Rut C30 and used for OPEFB hydrolysis. The filter paper cellulase activity of the crude cellulolytic enzymes was 15.1 IU/mL, which was higher than those obtained by reported Trichoderma strains under laboratory conditions. Glucose and xylose yields reached 66.9% and 74.2%, respectively, at 30 filter paper unit (FPU)/g-biomass enzyme dosage and 10% (w/v) biomass loading. The hybrid yeast strain ScF2 was previously constructed through recursive genome shuffling of Pichia stipitis and Saccharomyces cerevisiae and was used in OPEFB hydrolysate fermentation. About 16.9 g/L ethanol was produced with an ethanol yield of 0.34 g/g sugars, which was 67% of theoretical ethanol yield.


Assuntos
Etanol/metabolismo , Microbiologia Industrial , Óleo de Palmeira/metabolismo , Leveduras/metabolismo , Biocatálise , Biomassa , Celulase/metabolismo , Fermentação , Frutas/metabolismo , Proteínas Fúngicas/metabolismo , Hidrólise , Hypocreales/enzimologia , Hypocreales/metabolismo , Lignina/metabolismo , Pichia/enzimologia , Pichia/metabolismo , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/metabolismo , Xilose/metabolismo , Leveduras/enzimologia
4.
Biochemistry ; 58(34): 3592-3603, 2019 08 27.
Artigo em Inglês | MEDLINE | ID: mdl-31398016

RESUMO

Fusobacterium nucleatum is a common oral bacterium and a major producer of H2S, a toxic gas linked to the pathogenesis of periodontal disease. The bacterium encodes a fold type II pyridoxal l-phosphate (PLP)-dependent enzyme, Fn1220 or lanthionine synthase (LS), that generates H2S and l-lanthionine (a component of the peptidoglycan layer) through ß-replacement of l-cysteine by a second molecule of l-cysteine. Herein, we show through detailed kinetic analysis that LS elicits catalytic promiscuity as demonstrated for other fold type II PLP-dependent homologues, namely, O-acetylserine sulfhydrylase (OASS) and cystathionine ß-synthase (CBS). Like OASS, LS can assimilate H2S by catalyzing the ß-replacement of O-acetyl-l-serine by sulfide to form l-cysteine. However, the turnover for this reaction in LS is slower than that of other studied OASS enzymes due to slower conversion to the α-aminoacrylate intermediate. Similar to yeast and human CBS, LS can generate H2S and l-cystathionine through ß-replacement of l-cysteine by a second molecule of l-homocysteine; however, whereas this is the main H2S-forming reaction in CBS, it is not for LS. LS shows a marked preference for forming H2S and l-lanthionine through the condensation of 2 equiv of l-cysteine. Sequence alignment of LS with other CBS and OASS enzymes and inspection of the LS crystal structure in the external aldimine state with l-lanthionine reveal that LS possesses a unique loop that engages in hydrogen-bond contact with the product, providing a structural rationale for the enzyme's catalytic preference for H2S and l-lanthionine biosynthesis.


Assuntos
Alanina/análogos & derivados , Cisteína/metabolismo , Fusobacterium nucleatum/enzimologia , Hidroliases/metabolismo , Complexos Multienzimáticos/metabolismo , Alanina/biossíntese , Proteínas de Bactérias/metabolismo , Cistationina beta-Sintase , Cisteína Sintase , Fusobacterium nucleatum/metabolismo , Humanos , Sulfeto de Hidrogênio/metabolismo , Cinética , Conformação Proteica , Fosfato de Piridoxal , Relação Estrutura-Atividade , Sulfetos , Leveduras/enzimologia
5.
J Agric Food Chem ; 67(31): 8617-8625, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31293160

RESUMO

Inhibiting starch digestion can effectively control postprandial blood sugar level. In this study, the in vitro digestion differences among the mixtures of five polyphenols (i.e., procyanidins [PAs], catechin [CA], tannic acid [TA], rutin [RU], and quercetin [QU]) and starch were analyzed through an in vitro simulation test of starch digestion. The interaction characteristics of these five polyphenols with α-amylase and α-glucosidase were investigated in terms of the inhibition effect, dynamics, fluorescence quenching, and circular dichroism (CD). The results revealed that the rapidly digestible starch (RDS) contents decreased, while the resistant starch (RS) contents increased. All five polyphenols inhibited the α-amylase activity through the noncompetitive approach but inhibited the α-glucosidase activity through the competitive approach. Five polyphenols combined with α-amylase spontaneously by using the hydrophobic effect. The interaction of PAs and QU with α-glucosidase were recognized as van der Waals forces and H bonding, whereas CA and TA interacted with α-glucosidase through the hydrophobic effect. All five polyphenols can cause conformational changes in enzymes.


Assuntos
Extratos Vegetais/química , Polifenóis/química , Amido/química , Animais , Digestão , Inibidores Enzimáticos/química , Inibidores Enzimáticos/metabolismo , Proteínas Fúngicas/química , Proteínas Fúngicas/metabolismo , Cinética , Modelos Biológicos , Extratos Vegetais/metabolismo , Polifenóis/metabolismo , Amido/metabolismo , Suínos , Leveduras/enzimologia , alfa-Amilases/química , alfa-Amilases/metabolismo , alfa-Glucosidases/química , alfa-Glucosidases/metabolismo
6.
Bioconjug Chem ; 30(2): 432-442, 2019 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-30615416

RESUMO

Proteins are ideal candidates for disease treatment because of their high specificity and potency. Despite this potential, delivery of proteins remains a significant challenge due to the intrinsic size, charge, and stability of proteins. Attempts to overcome these challenges have most commonly relied on direct conjugation of polymers and peptides to proteins via reactive groups on naturally occurring residues. While such approaches have shown some success, they allow limited control of the spacing and number of moieties coupled to proteins, which can hinder bioactivity and delivery capabilities of the therapeutic. Here, we describe a strategy to site-specifically conjugate delivery moieties to therapeutic proteins through unnatural amino acid (UAA) incorporation, in order to explore the effect of epidermal growth factor receptor (EGFR)-targeted ligand valency and spacing on internalization of proteins in EGFR-overexpressing inflammatory breast cancer (IBC) cells. Our results demonstrate the ability to enhance targeted protein delivery by tuning a small number of EGFR ligands per protein and clustering these ligands to promote multivalent ligand-receptor interactions. Furthermore, the tailorability of this simple approach was demonstrated through IBC-targeted cell death via the delivery of yeast cytosine deaminase (yCD), a prodrug converting enzyme.


Assuntos
Aminoácidos/metabolismo , Citosina Desaminase/administração & dosagem , Proteínas Luminescentes/administração & dosagem , Aminoácidos/química , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Química Click , Citosina Desaminase/química , Citosina Desaminase/farmacocinética , Sistemas de Liberação de Medicamentos , Receptores ErbB/metabolismo , Feminino , Humanos , Ligantes , Proteínas Luminescentes/química , Proteínas Luminescentes/farmacocinética , Modelos Moleculares , Ligação Proteica , Leveduras/enzimologia , Proteína Vermelha Fluorescente
7.
Methods Mol Biol ; 1895: 75-85, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30539530

RESUMO

Exosomes derived from human mesenchymal stem cells (MSCs) engineered to express the suicide gene yeast cytosine deaminase::uracil phosphoribosyl transferase (yCD::UPRT) represent a new therapeutic approach for tumor-targeted innovative therapy. The yCD::UPRT-MSC-exosomes carry mRNA of the suicide gene in their cargo. Upon internalization by tumor cells, the exosomes inhibit the growth of broad types of cancer cells in vitro, in the presence of a prodrug. Here we describe the method leading to the production and testing of these therapeutic exosomes. The described steps include the preparation of replication-deficient retrovirus possessing the yCD::UPRT suicide gene, and the preparation and selection of MSCs transduced with yCD::UPRT suicide gene. We present procedures to obtain exosomes possessing the ability to induce the death of tumor cells. In addition, we highlight methods for the evaluation of the suicide gene activity of yCD::UPRT-MSC-exosomes.


Assuntos
Exossomos , Genes Transgênicos Suicidas , Terapia Genética/métodos , Neoplasias/terapia , Retroviridae/genética , Animais , Linhagem Celular , Citosina Desaminase/genética , Portadores de Fármacos , Proteínas Fúngicas/genética , Vetores Genéticos , Humanos , Células-Tronco Mesenquimais , Camundongos , Pentosiltransferases/genética , Leveduras/enzimologia
8.
Methods Mol Biol ; 1895: 87-96, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30539531

RESUMO

Gene therapy involves the introduction of genes (termed transgenes) into cells to compensate for a deficiency or to make a beneficial protein. Gene therapy can used as a form of cancer treatment. A particularly attractive paradigm in this regard involves the selective introduction of transgenes into cancer cells that converts inactive prodrugs into active chemotherapeutic agents, thereby triggering the death of cancer cells. Since prodrugs are inactive, they tend not to cause significant side-effects and are well-tolerated by patients relative to conventional chemotherapy. Several viral and nonviral vectors have been used as delivery tools for suicide gene therapy. Extracellular vesicles (EVs) are now recognized as a promising class of nonviral delivery vectors. Here, we describe a method in which a suicide fusion gene construct is loaded into EVs derived from a non-tumorigenic cell line. Delivery of these modified EVs to glioblastoma cell lines and spheroids decreases glioblastoma cell viability, induces apoptotic cell death, and inhibits tumor growth in vivo.


Assuntos
Portadores de Fármacos , Vesículas Extracelulares , Genes Transgênicos Suicidas , Terapia Genética/métodos , Glioblastoma/terapia , Linhagem Celular Tumoral , Citosina Desaminase/metabolismo , Proteínas Fúngicas/metabolismo , Glioblastoma/tratamento farmacológico , Células HEK293 , Humanos , Pentosiltransferases/metabolismo , Pró-Fármacos/metabolismo , Pró-Fármacos/uso terapêutico , RNA Mensageiro , Leveduras/enzimologia
9.
Methods Mol Biol ; 1895: 135-147, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30539535

RESUMO

When using bicistronic expression constructs the issue arises concerning proper evaluation of the cytotoxic efficiency of a combination of therapeutic genes. For this purpose, an approach can be applied based on the transient transfection of cultured human cells with a specifically designed set of mono- and bicistronic expression constructs and on the comparison of their cytotoxic effects. Here the application of this approach is described using an example of the evaluation of the combined cytotoxic action of bifunctional yeast cytosine deaminase/uracil phosphoribosyltransferase fusion protein (FCU1) and hepatitis A virus 3C protease in a bicistronic plasmid construct.


Assuntos
Cisteína Endopeptidases/genética , Citosina Desaminase/genética , Genes Transgênicos Suicidas , Terapia Genética/métodos , Vetores Genéticos , Pentosiltransferases/genética , Proteínas Virais/genética , Proteases Virais 3C , Proteínas Fúngicas , Humanos , Plasmídeos , Proteínas Recombinantes de Fusão/genética , Leveduras/enzimologia
10.
PLoS One ; 13(8): e0201198, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30070990

RESUMO

ISOPENTENYLTRANSFERASE (IPT) genes play important roles in the initial steps of cytokinin synthesis, exist in plant and pathogenic bacteria, and form a multigene family in plants. Protein domain searches revealed that bacteria and plant IPT proteins were to assigned to different protein domains families in the Pfam database, namely Pfam IPT (IPTPfam) and Pfam IPPT (IPPTPfam) families, both are closely related in the P-loop NTPase clan. To understand the origin and evolution of the genes, a species matrix was assembled across the tree of life and intensively in plant lineages. The IPTPfam domain was only found in few bacteria lineages, whereas IPPTPfam is common except in Archaea and Mycoplasma bacteria. The bacterial IPPTPfam domain miaA genes were shown as ancestral of eukaryotic IPPTPfam domain genes. Plant IPTs diversified into class I, class II tRNA-IPTs, and Adenosine-phosphate IPTs; the class I tRNA-IPTs appeared to represent direct successors of miaA genes were found in all plant genomes, whereas class II tRNA-IPTs originated from eukaryotic genes, and were found in prasinophyte algae and in euphyllophytes. Adenosine-phosphate IPTs were only found in angiosperms. Gene duplications resulted in gene redundancies with ubiquitous expression or diversification in expression. In conclusion, it is shown that IPT genes have a complex history prior to the protein family split, and might have experienced losses or HGTs, and gene duplications that are to be likely correlated with the rise in morphological complexity involved in fine tuning cytokinin production.


Assuntos
Alquil e Aril Transferases/genética , Família Multigênica , Sequência de Aminoácidos , Animais , Archaea/enzimologia , Archaea/genética , Proteínas Arqueais/genética , Bactérias/enzimologia , Bactérias/genética , Proteínas de Bactérias/genética , Evolução Molecular , Proteínas Fúngicas/genética , Genoma de Planta , Micetozoários/enzimologia , Micetozoários/genética , Filogenia , Proteínas de Plantas/genética , Plantas/enzimologia , Plantas/genética , Domínios Proteicos , Leveduras/enzimologia , Leveduras/genética
11.
Inorg Chem ; 57(10): 5754-5766, 2018 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-29708337

RESUMO

Met80, one of the heme iron ligands in cytochrome c (cyt c), is readily oxidized to Met sulfoxide (Met-SO) by several biologically relevant oxidants. The modification has been suggested to affect both the electron-transfer (ET) and apoptotic functions of this metalloprotein. The coordination of the heme iron in Met-oxidized cyt c (Met-SO cyt c) is critical for both of these functions but has remained poorly defined. We present electronic absorption, NMR, and EPR spectroscopic investigations as well as kinetic studies and mutational analyses to identify the heme iron ligands in yeast iso-1 Met-SO cyt c. Similar to the alkaline form of native cyt c, Lys73 and Lys79 ligate to the ferric heme iron in the Met80-oxidized protein, but this coordination takes place at much lower pH. The ferrous heme iron is ligated by Met-SO, implying the redox-linked ligand switch in the modified protein. Binding studies with the model peptide microperoxidase-8 provide a rationale for alterations in ligation and for the role of the polypeptide packing in native and Met-SO cyt c. Imidazole binding experiments have revealed that Lys dissociation from the ferric heme in K73A/K79G/M80K (M80K#) and Met-SO is more than 3 orders of magnitude slower than the opening of the heme pocket that limits Met80 replacement in native cyt c. The Lys-to-Met-SO ligand substitution gates ET of ferric Met-SO cyt c with Co(terpy)22+. Owing to the slow Lys dissociation step, ET reaction is slow but possible, which is not the case for nonswitchable M80A and M80K#. Acidic conditions cause Lys replacement by a water ligand in Met-SO cyt c (p Ka = 6.3 ± 0.1), increasing the intrinsic peroxidase activity of the protein. This pH-driven ligand switch may be a mechanism to boost peroxidase function of cyt c specifically in apoptotic cells.


Assuntos
Citocromos c/metabolismo , Metionina/metabolismo , Sulfóxidos/química , Sequência de Aminoácidos , Sítios de Ligação , Citocromos c/química , Espectroscopia de Ressonância de Spin Eletrônica , Heme/química , Imidazóis/química , Ferro/química , Ligantes , Metionina/química , Modelos Biológicos , Oxirredução , Análise Espectral Raman , Leveduras/enzimologia
12.
Protein Sci ; 27(8): 1418-1426, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29696702

RESUMO

Immunoglobulin Binding Protein (BiP) is a chaperone and molecular motor belonging to the Hsp70 family, involved in the regulation of important biological processes such as synthesis, folding and translocation of proteins in the Endoplasmic Reticulum. BiP has two highly conserved domains: the N-terminal Nucleotide-Binding Domain (NBD), and the C-terminal Substrate-Binding Domain (SBD), connected by a hydrophobic linker. ATP binds and it is hydrolyzed to ADP in the NBD, and BiP's extended polypeptide substrates bind in the SBD. Like many molecular motors, BiP function depends on both structural and catalytic properties that may contribute to its performance. One novel approach to study the mechanical properties of BiP considers exploring the changes in the viscoelastic behavior upon ligand binding, using a technique called nano-rheology. This technique is essentially a traditional rheology experiment, in which an oscillatory force is directly applied to the protein under study, and the resulting average deformation is measured. Our results show that the folded state of the protein behaves like a viscoelastic material, getting softer when it binds nucleotides- ATP, ADP, and AMP-PNP-, but stiffer when binding HTFPAVL peptide substrate. Also, we observed that peptide binding dramatically increases the affinity for ADP, decreasing it dissociation constant (KD ) around 1000 times, demonstrating allosteric coupling between SBD and NBD domains.


Assuntos
Proteínas de Choque Térmico , Nanotecnologia/métodos , Reologia/métodos , Animais , Elasticidade , Chaperona BiP do Retículo Endoplasmático , Desenho de Equipamento , Proteínas de Choque Térmico/química , Proteínas de Choque Térmico/genética , Proteínas de Choque Térmico/metabolismo , Camundongos , Mutagênese Sítio-Dirigida , Nanotecnologia/instrumentação , Ligação Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Reologia/instrumentação , Viscosidade , Leveduras/enzimologia , Leveduras/genética
13.
Extremophiles ; 22(4): 599-606, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29516184

RESUMO

The present study was performed to screen for psychrophilic yeasts that are able to secrete cold active enzymes. Yeast isolates were obtained from environmental samples from northern Turkey and examined for enzyme production at low temperatures. The isolates which were capable of cold active enzyme production on plates were identified by molecular identification techniques. It has been found that the isolates belonged to three genera of yeasts, i.e., Rhodosporidiobolus, Cystofilobasidium and Yamadazyma. The isolates were then fermented in different media at 15 °C and the pectinase, amylase and protease activities were determined in the range of 0.76-1.73, 0.5-1.57 and 2.11-10.53 U/mL, respectively. Maximum enzyme activities were found in Yamadazyma isolates for all three enzymes. To the best of our knowledge, cold active pectinase, amylase and protease production by Yamadazyma spp. were investigated for the first time in the present study. Besides, this is the first report which indicates cold active amylase production by Cystofilobasidium capitatum and pectinase production by Rhodosporidiobolus colostri. Yeast isolates obtained in this study may have potential for industrial cold active enzyme production.


Assuntos
Amilases/metabolismo , Temperatura Baixa , Proteínas Fúngicas/metabolismo , Peptídeo Hidrolases/metabolismo , Poligalacturonase/metabolismo , Leveduras/enzimologia , Aclimatação , Amilases/genética , Proteínas Fúngicas/genética , Peptídeo Hidrolases/genética , Poligalacturonase/genética , Leveduras/isolamento & purificação , Leveduras/fisiologia
14.
Molecules ; 22(10)2017 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-28946698

RESUMO

The oleaginous yeast Moniliella spathulata R25L270 was the first yeast able to grow and produce extracellular lipase using Macaúba (Acrocomia aculeate) cake as substrate. The novel lipase was recently identified, and presented promising features for biotechnological applications. The M. spathulata R25L270 lipase efficiently hydrolyzed vegetable and animal oils, and showed selectivity for generating cis-5,8,11,15,17-eicosapentaenoic acid from sardine oil. The enzyme can act in a wide range of temperatures (25-48 °C) and pH (6.5-8.4). The present study deals with the immobilization of M. spathulata R25L270 lipase on hydrophobic, covalent and ionic supports to select the most active biocatalyst capable to obtain omega-3 fatty acids (PUFA) from sardine oil. Nine immobilized agarose derivatives were prepared and biochemically characterized for thermostability, pH stability and catalytic properties (KM and Vmax). Ionic supports improved the enzyme-substrate affinity; however, it was not an effective strategy to increase the M. spathulata R25L270 lipase stability against pH and temperature. Covalent support resulted in a biocatalyst with decreased activity, but high thermostability. The enzyme was most stabilized when immobilized on hydrophobic supports, especially Octyl-Sepharose. Compared with the free enzyme, the half-life of the Octyl-Sepharose derivative at 60 °C increased 10-fold, and lipase stability under acidic conditions was achieved. The Octyl-Sepharose derivative was selected to obtain omega-3 fatty acids from sardine oil, and the maximal enzyme selectivity was achieved at pH 5.0.


Assuntos
Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Óleos de Peixe/metabolismo , Lipase/química , Lipase/metabolismo , Leveduras/enzimologia , Estabilidade Enzimática , Ácidos Graxos Ômega-3/metabolismo , Hidrólise , Interações Hidrofóbicas e Hidrofílicas
15.
Biosens Bioelectron ; 91: 341-346, 2017 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-28043076

RESUMO

Exhaled breath analysis has attracted lots of researchers attention in the past decades due to its advantages such as its non-invasive property and the possibility of continuous monitoring. In addition, several volatile organic compounds in breath have been identified as biomarkers for some diseases. Particularly, studies have pointed out that concentration of isopropanol (IPA) in exhaled air might relate with certain illnesses such as liver disease, chronic obstructive pulmonary (COPD), and lung cancer. In this study, a highly sensitive and selective biochemical gas sensor (bio-sniffer) for the breath IPA concentration determination was constructed and optimized. This bio-sniffer measures the concentration of IPA according to the fluorescence intensity of oxidized nicotinamide adenine dinucleotide (NADH), which was produced by an enzymatic reaction of secondary alcohol dehydrogenase (S-ADH). The NADH detection system employed an UV-LED as the excitation light, and a highly sensitive photomultiplier tube (PMT) as a fluorescence intensity detector. A gas-sensing region was developed using an optical fiber probe equipped with a flow-cell and enzyme immobilized membrane, and connected to the NADH measurement system. The calibration range of the IPA bio-sniffer was confirmed from 1ppb to 9060ppb that was comparable to other IPA analysis methods. The results of the analysis of breath IPA concentration in healthy subjects using the bio-sniffer showed a mean concentration of 16.0ppb, which was similar to other studies. These results have demonstrated that this highly sensitive and selective bio-sniffer could be used to measure the IPA in exhaled air, and it is expected to apply for breath IPA research and investigation of biomarkers for clinical diagnosis.


Assuntos
2-Propanol/análise , Oxirredutases do Álcool/metabolismo , Técnicas Biossensoriais/instrumentação , Testes Respiratórios/instrumentação , Enzimas Imobilizadas/metabolismo , Leveduras/enzimologia , 2-Propanol/metabolismo , Adulto , Desenho de Equipamento , Feminino , Humanos , Masculino , Adulto Jovem
16.
Extremophiles ; 21(2): 319-329, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28004216

RESUMO

One hundred and three yeasts isolated from soil samples from King George Island and Tierra del Fuego province were screened in relation with their capability to produce pectinolytic enzymes. Although all the yeasts showed well-developed colonies at 20 °C, only eight showed a clear halo around the colony, indicative of pectin degradation. A secondary screening demonstrated that only four yeasts were capable to produce pectinases at low temperatures (8 °C). It could be seen that the selected yeasts were able to grow and produce high levels of polygalacturonase activity when submerged fermentations were performed using pectin-containing fruit wastes as substrates. None of the strains produced neither lyase nor rhamnogalacturonan hydrolase activities. Regarding pectin esterase activity, it was only produced in lower amounts by G. pullulans 8E (0.022 U ml-1). A TLC analysis of the substrate cleavage pattern of the pectinolytic systems was consistent with an endo-type activity. The clarification of apple juice was only accomplished by G. pullulans pectinolytic system, with a clarification of 80% (%T650) using 4 U/ml of enzyme at 20 °C. As far as we concern this work describes for the first time the production of pectinases by the cold-adapted yeasts species Cystofilobasidium infirmominiatum, Cryptococcus adeliensis and G. pullulans.


Assuntos
Basidiomycota/enzimologia , Temperatura Baixa , Proteínas Fúngicas/biossíntese , Poligalacturonase/biossíntese , Microbiologia do Solo , Leveduras/enzimologia , Basidiomycota/classificação , Leveduras/classificação
17.
J Am Chem Soc ; 138(37): 12124-41, 2016 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-27571509

RESUMO

The enzyme cytochrome P450 11A1 cleaves the C20-C22 carbon-carbon bond of cholesterol to form pregnenolone, the first 21-carbon precursor of all steroid hormones. Various reaction mechanisms are possible for the carbon-carbon bond cleavage step of P450 11A1, and most current proposals involve the oxoferryl active species, Compound I (FeO(3+)). Compound I can either (i) abstract an O-H hydrogen atom or (ii) be attacked by a nucleophilic hydroxy group of its substrate, 20R,22R-dihydroxycholesterol. The mechanism of this carbon-carbon bond cleavage step was tested using (18)O-labeled molecular oxygen and purified P450 11A1. P450 11A1 was incubated with 20R,22R-dihydroxycholesterol in the presence of molecular oxygen ((18)O2), and coupled assays were used to trap the labile (18)O atoms in the enzymatic products (i.e., isocaproaldehyde and pregnenolone). The resulting products were derivatized and the (18)O content was analyzed by high-resolution mass spectrometry. P450 11A1 showed no incorporation of an (18)O atom into either of its carbon-carbon bond cleavage products, pregnenolone and isocaproaldehyde . The positive control experiments established retention of the carbonyl oxygens in the enzymatic products during the trapping and derivatization processes. These results reveal a mechanism involving an electrophilic Compound I species that reacts with nucleophilic hydroxy groups in the 20R,22R-dihydroxycholesterol intermediate of the P450 11A1 reaction to produce the key steroid pregnenolone.


Assuntos
Carbono/química , Enzima de Clivagem da Cadeia Lateral do Colesterol/química , Enzima de Clivagem da Cadeia Lateral do Colesterol/metabolismo , Colesterol/química , Compostos Férricos/química , Álcool Desidrogenase/metabolismo , Caproatos/química , Caproatos/metabolismo , Colesterol/metabolismo , Marcação por Isótopo , Oxigênio/química , Oxigênio/metabolismo , Leveduras/enzimologia
18.
Biochem Biophys Res Commun ; 468(1-2): 143-50, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26522225

RESUMO

Regulation of proteasomal degradation is an indispensable tool for biomedical studies. Thus, there is demand for novel proteasome inhibitors. Proteasomal degradation requires formation of coiled-coil structure by the N-terminal region of ATPase subunits of the proteasome cap. Here we show that peptides that mimic the N-terminal coiled-coil region of ATPase subunits interfere with proteasome function. These results suggest that coiled-coil peptides represent promising new proteasome inhibitors and that N-terminal coiled-coil regions of ATPase subunits are targets for proteasome inhibition.


Assuntos
Peptídeos/química , Peptídeos/farmacologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Inibidores de Proteassoma/química , Inibidores de Proteassoma/farmacologia , Adenosina Trifosfatases/química , Adenosina Trifosfatases/metabolismo , Sequência de Aminoácidos , Humanos , Dados de Sequência Molecular , Complexo de Endopeptidases do Proteassoma/química , Leveduras/efeitos dos fármacos , Leveduras/enzimologia , Leveduras/crescimento & desenvolvimento
19.
Mol Syst Biol ; 11(10): 829, 2015 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-26446933

RESUMO

Cells must quickly respond and efficiently adapt to environmental changes. The yeast Saccharomyces cerevisiae has multiple pathways that respond to specific environmental insults, as well as a generic stress response program. The later is regulated by two transcription factors, Msn2 and Msn4, that integrate information from upstream pathways to produce fast, tunable, and robust response to different environmental changes. To understand this integration, we employed a systematic approach to genetically dissect the contribution of various cellular pathways to Msn2/4 regulation under a range of stress and growth conditions. We established a high-throughput liquid handling and automated flow cytometry system and measured GFP levels in 68 single-knockout and 1,566 double-knockout strains that carry an HSP12-GFP allele as a reporter for Msn2/4 activity. Based on the expression of this Msn2/4 reporter in five different conditions, we identified numerous genetic and epistatic interactions between different components in the network upstream to Msn2/4. Our analysis gains new insights into the functional specialization of the RAS paralogs in the repression of stress response and identifies a three-way crosstalk between the Mediator complex, the HOG MAPK pathway, and the cAMP/PKA pathway.


Assuntos
Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , AMP Cíclico/metabolismo , Sistema de Sinalização das MAP Quinases , Leveduras/enzimologia , Leveduras/metabolismo
20.
World J Microbiol Biotechnol ; 31(12): 1899-906, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26475328

RESUMO

The use of supplements in the diet is a common practice to address nutritional deficiencies. Selenium is an essential micronutrient with an antioxidant and anti-carcinogenic role in human and animal health. There is increasing interest in developing nutritional supplements such as yeast cells enriched with selenium. The possibility of producing beverages, namely wine, with selenium-enriched yeasts, led us to investigate the selenium tolerance of six wine related yeasts. The production of such cells may hamper selenium toxicity problems. Above certain concentrations selenium can be toxic inducing oxidative stress and yeast species can show different tolerance. This work aimed at studying selenium tolerance of a diversity of wine related yeasts, thus antioxidant response mechanisms with different concentrations of sodium selenite were evaluated. Viability assays demonstrated that the yeast Torulaspora delbrueckii showed the highest tolerance for the tested levels of 100 µg mL(-1) of sodium selenite. The evaluation of antioxidative enzyme activities showed the best performance for concentrations of 250 and 100 µg mL(-1), respectively for the yeast species Saccharomyces cerevisiae and Hanseniaspora guilliermondii. These results encourage future studies on the possibility to use pre-enriched yeast cells as selenium supplement in wine production.


Assuntos
Antioxidantes/farmacologia , Selenito de Sódio/farmacologia , Vinho/microbiologia , Leveduras/enzimologia , Antioxidantes/análise , Antioxidantes/metabolismo , Meios de Cultura , Relação Dose-Resposta a Droga , Fermentação , Hanseniaspora/enzimologia , Hanseniaspora/crescimento & desenvolvimento , Hanseniaspora/metabolismo , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/metabolismo , Selenito de Sódio/metabolismo , Torulaspora/enzimologia , Torulaspora/crescimento & desenvolvimento , Torulaspora/metabolismo , Leveduras/efeitos dos fármacos , Leveduras/metabolismo
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