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1.
Nat Rev Mol Cell Biol ; 25(4): 309-332, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38081975

RESUMO

The packaging of DNA into chromatin in eukaryotes regulates gene transcription, DNA replication and DNA repair. ATP-dependent chromatin remodelling enzymes (re)arrange nucleosomes at the first level of chromatin organization. Their Snf2-type motor ATPases alter histone-DNA interactions through a common DNA translocation mechanism. Whether remodeller activities mainly catalyse nucleosome dynamics or accurately co-determine nucleosome organization remained unclear. In this Review, we discuss the emerging mechanisms of chromatin remodelling: dynamic remodeller architectures and their interactions, the inner workings of the ATPase cycle, allosteric regulation and pathological dysregulation. Recent mechanistic insights argue for a decisive role of remodellers in the energy-driven self-organization of chromatin, which enables both stability and plasticity of genome regulation - for example, during development and stress. Different remodellers, such as members of the SWI/SNF, ISWI, CHD and INO80 families, process (epi)genetic information through specific mechanisms into distinct functional outputs. Combinatorial assembly of remodellers and their interplay with histone modifications, histone variants, DNA sequence or DNA-bound transcription factors regulate nucleosome mobilization or eviction or histone exchange. Such input-output relationships determine specific nucleosome positions and compositions with distinct DNA accessibilities and mediate differential genome regulation. Finally, remodeller genes are often mutated in diseases characterized by genome dysregulation, notably in cancer, and we discuss their physiological relevance.


Assuntos
Cromatina , Histonas , Humanos , Histonas/metabolismo , Nucleossomos , Adenosina Trifosfatases/metabolismo , Montagem e Desmontagem da Cromatina , DNA , Trifosfato de Adenosina/metabolismo
2.
Cell ; 162(5): 1066-77, 2015 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-26317470

RESUMO

Many proteins contain disordered regions of low-sequence complexity, which cause aging-associated diseases because they are prone to aggregate. Here, we study FUS, a prion-like protein containing intrinsically disordered domains associated with the neurodegenerative disease ALS. We show that, in cells, FUS forms liquid compartments at sites of DNA damage and in the cytoplasm upon stress. We confirm this by reconstituting liquid FUS compartments in vitro. Using an in vitro "aging" experiment, we demonstrate that liquid droplets of FUS protein convert with time from a liquid to an aggregated state, and this conversion is accelerated by patient-derived mutations. We conclude that the physiological role of FUS requires forming dynamic liquid-like compartments. We propose that liquid-like compartments carry the trade-off between functionality and risk of aggregation and that aberrant phase transitions within liquid-like compartments lie at the heart of ALS and, presumably, other age-related diseases.


Assuntos
Envelhecimento/patologia , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/patologia , Mutação , Proteína FUS de Ligação a RNA/química , Proteína FUS de Ligação a RNA/genética , Envelhecimento/metabolismo , Esclerose Lateral Amiotrófica/metabolismo , Núcleo Celular/química , Citoplasma/química , Humanos , Príons/química , Agregados Proteicos , Estrutura Terciária de Proteína , Proteína FUS de Ligação a RNA/metabolismo
3.
Biophys J ; 120(7): 1170-1186, 2021 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-32853565

RESUMO

Although much is known about the biochemical regulation of glycolytic enzymes, less is understood about how they are organized inside cells. We systematically examine the dynamic subcellular localization of glycolytic protein phosphofructokinase-1/PFK-1.1 in Caenorhabditis elegans. We determine that endogenous PFK-1.1 localizes to subcellular compartments in vivo. In neurons, PFK-1.1 forms phase-separated condensates near synapses in response to energy stress from transient hypoxia. Restoring animals to normoxic conditions results in cytosolic dispersion of PFK-1.1. PFK-1.1 condensates exhibit liquid-like properties, including spheroid shapes due to surface tension, fluidity due to deformations, and fast internal molecular rearrangements. Heterologous self-association domain cryptochrome 2 promotes formation of PFK-1.1 condensates and recruitment of aldolase/ALDO-1. PFK-1.1 condensates do not correspond to stress granules and might represent novel metabolic subcompartments. Our studies indicate that glycolytic protein PFK-1.1 can dynamically form condensates in vivo.


Assuntos
Caenorhabditis elegans/enzimologia , Fosfofrutoquinase-1 , Fosfofrutoquinases , Animais , Glicólise , Organelas/metabolismo , Fosfofrutoquinase-1/genética , Fosfofrutoquinase-1/metabolismo , Fosforilação
4.
EMBO J ; 36(12): 1669-1687, 2017 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-28377462

RESUMO

Stress granules (SG) are membrane-less compartments involved in regulating mRNAs during stress. Aberrant forms of SGs have been implicated in age-related diseases, such as amyotrophic lateral sclerosis (ALS), but the molecular events triggering their formation are still unknown. Here, we find that misfolded proteins, such as ALS-linked variants of SOD1, specifically accumulate and aggregate within SGs in human cells. This decreases the dynamics of SGs, changes SG composition, and triggers an aberrant liquid-to-solid transition of in vitro reconstituted compartments. We show that chaperone recruitment prevents the formation of aberrant SGs and promotes SG disassembly when the stress subsides. Moreover, we identify a backup system for SG clearance, which involves transport of aberrant SGs to the aggresome and their degradation by autophagy. Thus, cells employ a system of SG quality control to prevent accumulation of misfolded proteins and maintain the dynamic state of SGs, which may have relevance for ALS and related diseases.


Assuntos
Grânulos Citoplasmáticos/metabolismo , Células Epiteliais/fisiologia , Chaperonas Moleculares/metabolismo , Superóxido Dismutase-1/metabolismo , Células HeLa , Humanos
5.
Soft Matter ; 16(24): 5659-5668, 2020 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-32519715

RESUMO

Macromolecules can phase separate to form liquid condensates, which are emerging as critical compartments in fields as diverse as intracellular organization and soft materials design. A myriad of macromolecules, including the protein FUS, form condensates which behave as isotropic liquids. Here, we investigate the influence of filament dopants on the material properties of protein liquids. We find that the short, biopolymer filaments of actin spontaneously partition into FUS droplets to form composite liquid droplets. As the concentration of the filament dopants increases, the coalescence time decreases, indicating that the dopants control viscosity relative to surface tension. The droplet shape is tunable and ranges from spherical to tactoid as the filament length or concentration is increased. We find that the tactoids are well described by a model of a quasi bipolar liquid crystal droplet, where nematic order from the anisotropic actin filaments competes with isotropic interfacial energy from the FUS, controlling droplet shape in a size-dependent manner. Our results demonstrate a versatile approach to construct tunable, anisotropic macromolecular liquids.


Assuntos
Citoesqueleto de Actina/química , Actinas/química , Proteína FUS de Ligação a RNA/química , Anisotropia , Cristais Líquidos , Modelos Teóricos , Tensão Superficial , Viscosidade
6.
Proc Natl Acad Sci U S A ; 112(50): E6844-51, 2015 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-26631750

RESUMO

Aromatic polyketides make up a large class of natural products with diverse bioactivity. During biosynthesis, linear poly-ß-ketone intermediates are regiospecifically cyclized, yielding molecules with defined cyclization patterns that are crucial for polyketide bioactivity. The aromatase/cyclases (ARO/CYCs) are responsible for regiospecific cyclization of bacterial polyketides. The two most common cyclization patterns are C7-C12 and C9-C14 cyclizations. We have previously characterized three monodomain ARO/CYCs: ZhuI, TcmN, and WhiE. The last remaining uncharacterized class of ARO/CYCs is the di-domain ARO/CYCs, which catalyze C7-C12 cyclization and/or aromatization. Di-domain ARO/CYCs can further be separated into two subclasses: "nonreducing" ARO/CYCs, which act on nonreduced poly-ß-ketones, and "reducing" ARO/CYCs, which act on cyclized C9 reduced poly-ß-ketones. For years, the functional role of each domain in cyclization and aromatization for di-domain ARO/CYCs has remained a mystery. Here we present what is to our knowledge the first structural and functional analysis, along with an in-depth comparison, of the nonreducing (StfQ) and reducing (BexL) di-domain ARO/CYCs. This work completes the structural and functional characterization of mono- and di-domain ARO/CYCs in bacterial type II polyketide synthases and lays the groundwork for engineered biosynthesis of new bioactive polyketides.


Assuntos
Aromatase/metabolismo , Policetídeo Sintases/química , Policetídeo Sintases/metabolismo , Aromatase/química , Aromatase/genética , Modelos Moleculares , Mutagênese , Policetídeo Sintases/genética , Conformação Proteica
7.
Mol Cell Proteomics ; 14(1): 243-50, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25368411

RESUMO

Stable Isotope Labeling by Amino Acids (SILAC) is a commonly used method in quantitative proteomics. Because of compatibility with trypsin digestion, arginine and lysine are the most widely used amino acids for SILAC labeling. We observed that Schizosaccharomyces pombe (fission yeast) cannot be labeled with a specific form of arginine, (13)C(6) (15)N(4)-arginine (Arg-10), which limits the exploitation of SILAC technology in this model organism. We hypothesized that in the fission yeast the guanidinium group of (13)C(6) (15)N(4)-arginine is catabolized by arginase and urease activity to (15)N1-labeled ammonia that is used as a precursor for general amino acid biosynthesis. We show that disruption of Ni(2+)-dependent urease activity, through deletion of the sole Ni(2+) transporter Nic1, blocks this recycling in ammonium-supplemented EMMG medium to enable (13)C(6) (15)N(4)-arginine labeling for SILAC strategies in S. pombe. Finally, we employed Arg-10 in a triple-SILAC experiment to perform quantitative comparison of G1 + S, M, and G2 cell cycle phases in S. pombe.


Assuntos
Arginina/metabolismo , Proteínas de Transporte de Cátions/genética , Marcação por Isótopo/métodos , Proteínas de Schizosaccharomyces pombe/genética , Isótopos de Carbono , Ciclo Celular , Isótopos de Nitrogênio , Proteômica/métodos , Schizosaccharomyces/genética , Schizosaccharomyces/metabolismo
8.
J Cell Sci ; 126(Pt 21): 5052-61, 2013 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-23986474

RESUMO

The chemical genetic strategy in which mutational enlargement of the ATP-binding site sensitises of a protein kinase to bulky ATP analogues has proved to be an elegant tool for the generation of conditional analogue-sensitive kinase alleles in a variety of model organisms. Here, we describe a novel substitution mutation in the kinase domain that can enhance the sensitivity of analogue-sensitive kinases. Substitution of a methionine residue to phenylalanine in the +2 position after HRDLKxxN motif of the subdomain VIb within the kinase domain markedly increased the sensitivities of the analogue-sensitive kinases to ATP analogues in three out of five S. pombe kinases (i.e. Plo1, Orb5 and Wee1) that harbor this conserved methionine residue. Kinome alignment established that a methionine residue is found at this site in 5-9% of kinases in key model organisms, suggesting that a broader application of this structural modification may enhance ATP analogue sensitivity of analogue-sensitive kinases in future studies. We also show that the enhanced sensitivity of the wee1.as8 allele in a cdc25.22 background can be exploited to generate highly synchronised mitotic and S phase progression at 36°C. Proof-of-principle experiments show how this novel synchronisation technique will prove of great use in the interrogation of the mitotic or S-phase functions through temperature sensitivity mutation of molecules of interest in fission yeast.


Assuntos
Trifosfato de Adenosina/metabolismo , Caseína Quinase II/genética , Proteínas de Ciclo Celular/genética , Mitose , Mutação de Sentido Incorreto , Proteínas Nucleares/genética , Proteínas Serina-Treonina Quinases/genética , Proteínas Tirosina Quinases/genética , Proteínas de Schizosaccharomyces pombe/genética , Schizosaccharomyces/enzimologia , Trifosfato de Adenosina/análogos & derivados , Substituição de Aminoácidos , Caseína Quinase II/química , Caseína Quinase II/metabolismo , Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/metabolismo , Sequência Conservada , Inibidores Enzimáticos/química , Inibidores Enzimáticos/metabolismo , Metionina/genética , Metionina/metabolismo , Proteínas Nucleares/química , Proteínas Nucleares/metabolismo , Fenilalanina/genética , Fenilalanina/metabolismo , Fosfoproteínas Fosfatases/genética , Fosfoproteínas Fosfatases/metabolismo , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/metabolismo , Estrutura Terciária de Proteína , Proteínas Tirosina Quinases/química , Proteínas Tirosina Quinases/metabolismo , Schizosaccharomyces/citologia , Schizosaccharomyces/genética , Proteínas de Schizosaccharomyces pombe/química , Proteínas de Schizosaccharomyces pombe/metabolismo
9.
Gene ; 890: 147798, 2024 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-37726026

RESUMO

Histones are subject to a diverse array of post-translational modifications. Among them, lysine acetylation is not only the most pervasive and dynamic modification but also highly consequential for regulating gene transcription. Although enzymes responsible for the addition and removal of acetyl groups were discovered almost 30 years ago, high-resolution structures of the enzymes in the context of their native complexes are only now beginning to become available, thanks to revolutionary technologies in protein structure determination and prediction. Here, we will review our current understanding of the molecular mechanisms of acetylation and deacetylation engendered by chromatin-modifying complexes, compare and contrast shared features, and discuss some of the pressing questions for future studies.


Assuntos
Histonas , Processamento de Proteína Pós-Traducional , Histonas/metabolismo , Acetilação , Biologia
10.
bioRxiv ; 2024 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-39131301

RESUMO

H2A.Z is a conserved histone variant that is localized to specific genomic regions where it plays important roles in transcription, DNA repair, and replication. Central to the biochemistry of human H2A.Z are the SRCAP and TIP60 chromatin remodelers, homologs of yeast SWR1 which catalyzes ATP-dependent H2A.Z exchange. Here, we use cryo-electron microscopy to resolve six structural states of the native SRCAP complex, uncovering conformational intermediates interpreted as a stepwise path to full nucleosome engagement. We also resolve the structure of the native TIP60 complex which consists of a structured core from which flexibly tethered chromatin binding domains emerge. Despite the shared subunit composition, the core of TIP60 displays divergent architectures from SRCAP that structurally disfavor nucleosome engagement, suggesting a distinct biochemical function.

11.
Nat Commun ; 14(1): 3061, 2023 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-37244892

RESUMO

The Rpd3L histone deacetylase (HDAC) complex is an ancient 12-subunit complex conserved in a broad range of eukaryotes that performs localized deacetylation at or near sites of recruitment by DNA-bound factors. Here we describe the cryo-EM structure of this prototypical HDAC complex that is characterized by as many as seven subunits performing scaffolding roles for the tight integration of the only catalytic subunit, Rpd3. The principal scaffolding protein, Sin3, along with Rpd3 and the histone chaperone, Ume1, are present in two copies, with each copy organized into separate lobes of an asymmetric dimeric molecular assembly. The active site of one Rpd3 is completely occluded by a leucine side chain of Rxt2, while the tips of the two lobes and the more peripherally associated subunits exhibit varying levels of flexibility and positional disorder. The structure reveals unexpected structural homology/analogy between unrelated subunits in the fungal and mammalian complexes and provides a foundation for deeper interrogations of structure, biology, and mechanism of these complexes, as well as for the discovery of HDAC complex-specific inhibitors.


Assuntos
Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Saccharomyces cerevisiae/metabolismo , Fatores de Transcrição/metabolismo , Proteínas Repressoras/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Histona Desacetilases/metabolismo , Microscopia Crioeletrônica , Regulação Fúngica da Expressão Gênica
12.
Foods ; 11(4)2022 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-35205996

RESUMO

A quick, simple, and reliable isocratic ultra-performance supercritical fluid chromatography-photodiode array detector (UPSFC-DAD) method was developed and validated to determine lycopene in different horticultural products. The effects of stationary phase, co-solvent, pressure, temperature, flow rate, and mobile phase additive on the separation of lycopene were evaluated. The developed method involved BEH-2EP-2.1 × 150 mm, 5 µm as the stationary phase, and CO2/MeOH 85:15 (v/v) with formic acid as the additive at 0.10% as the mobile phase. The column temperature was maintained at 45 °C, ABPR at 1800 psi, and the mobile phase's flow rate was maintained at 1 mL/min. Under the optimized conditions, lycopene was successfully separated within 0.722 ± 0.001 min. The standard curve assayed over a range of 10 to 100 µg/mL resulted in a correlation coefficient of 0.998. The mean recoveries between 97.38% and 102.67% at different spiking levels with RSD < 2.5% were achieved. The intra and inter-day precision expressed as relative standard deviations (RSD) were found to range from 1.27% to 3.28% and from 1.57% to 4.18%, respectively. Robustness in terms of retention time (tR) and RSD were found to be 0.93 ± 0.23 min and less <2.80%, respectively. The limits of detection and quantification were 0.14 µg/mL and 0.37 µg/mL, respectively. This method was successfully applied to determine lycopene extracted from papaya, grapefruit, and bitter melon.

13.
Front Mol Biosci ; 9: 1007744, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36483537

RESUMO

Biomolecular condensates are compartmentalized communities of biomolecules, which unlike traditional organelles, are not enclosed by membranes. Condensates play roles in diverse cellular processes, are dysfunctional in many disease states, and are often enriched in classically "undruggable" targets. In this review, we provide an overview for how drugs can modulate condensate structure and function by phenotypically classifying them as dissolvers (dissolve condensates), inducers (induce condensates), localizers (alter localization of the specific condensate community members) or morphers (alter the physiochemical properties). We discuss the growing list of bioactive molecules that function as condensate modifiers (c-mods), including small molecules, oligonucleotides, and peptides. We propose that understanding mechanisms of condensate perturbation of known c-mods will accelerate the discovery of a new class of therapies for difficult-to-treat diseases.

14.
Elife ; 112022 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-36263929

RESUMO

The NuA4 protein complex acetylates histones H4 and H2A to activate both transcription and DNA repair. We report the 3.1-Å resolution cryo-electron microscopy structure of the central hub of NuA4, which flexibly tethers the histone acetyltransferase (HAT) and Trimer Independent of NuA4 involved in Transcription Interactions with Nucleosomes (TINTIN) modules. The hub contains the large Tra1 subunit and a core that includes Swc4, Arp4, Act1, Eaf1, and the C-terminal region of Epl1. Eaf1 stands out as the primary scaffolding factor that interacts with the Tra1, Swc4, and Epl1 subunits and contributes the conserved HSA helix to the Arp module. Using nucleosome-binding assays, we find that the HAT module, which is anchored to the core through Epl1, recognizes H3K4me3 nucleosomes with hyperacetylated H3 tails, while the TINTIN module, anchored to the core via Eaf1, recognizes nucleosomes that have hyperacetylated H2A and H4 tails. Together with the known interaction of Tra1 with site-specific transcription factors, our data suggest a model in which Tra1 recruits NuA4 to specific genomic sites then allowing the flexible HAT and TINTIN modules to select nearby nucleosomes for acetylation.


Assuntos
Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Nucleossomos/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Microscopia Crioeletrônica , Histona Acetiltransferases/metabolismo , Acetilação
15.
Sci Rep ; 11(1): 10273, 2021 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-33986424

RESUMO

In this study, an underutilized citrus family fruit named grapefruit was explored for the extraction of lycopene using supercritical carbon dioxide (CO2) extraction technique. An experimental design was developed using response surface methodology to investigate the effect of supercritical carbon dioxide (CO2) operating parameter viz., pressure, temperature, CO2 flow rate, and extraction time on the extraction yield of lycopene yield from grapefruit. A total of 30 sets of experiments were conducted with six central points. The statistical model indicated that extraction pressure and extraction time individually, and their interaction, significantly affected the lycopene yield. The central composite design showed that the polynomial regression models developed were in agreement with the experimental results, with R2 of 0.9885. The optimum conditions for extraction of lycopene from grapefruit were 305 bar pressure, 35 g/min CO2 flow rate, 135 min of extraction time, and 70 °C temperature.


Assuntos
Dióxido de Carbono/química , Cromatografia com Fluido Supercrítico/métodos , Citrus paradisi/química , Licopeno/isolamento & purificação , Pressão , Temperatura
16.
Curr Opin Struct Biol ; 61: 17-24, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31751889

RESUMO

TFIID is a large multiprotein assembly that serves as a general transcription factor for transcription initiation by eukaryotic RNA polymerase II (Pol II). TFIID is involved in the recognition of the core promoter sequences and neighboring chromatin marks, and can interact with gene-specific activators and repressors. In order to obtain a better molecular and mechanistic understanding of the function of TFIID, its structure has been pursued for many years. However, the scarcity of TFIID and its highly flexible nature have made this pursuit very challenging. Recent breakthroughs, largely due to methodological advances in cryo-electron microscopy, have finally described the structure of this complex, both alone and engaged with core promoter DNA, revealing the functional significance of its conformational complexity in the process of core promoter recognition and initiation of Pol II transcription. Here, we review these recent structural insights and discuss their implications for our understanding of eukaryotic transcription initiation.


Assuntos
Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Regiões Promotoras Genéticas , Conformação Proteica , Fator de Transcrição TFIID/química , Sequência de Aminoácidos , Proteínas Fúngicas/química , Proteínas Fúngicas/metabolismo , Humanos , Conformação Molecular , Ligação Proteica , Relação Estrutura-Atividade , Proteína de Ligação a TATA-Box/química , Proteína de Ligação a TATA-Box/metabolismo , Fator de Transcrição TFIID/metabolismo
17.
Sci Rep ; 10(1): 10198, 2020 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-32576906

RESUMO

A trend of present encapsulation research indicates an increased interest in the search for natural encapsulants for bioactive phytochemicals. The present study in pursuit of the same studies the use of jackfruit seed starch (JSS), an underutilized natural polysaccharide in conjugation with soy protein isolate (SPI) as an encapsulating material and NBRE-15 as an emulsifier. Three independent variables viz., total soluble solids (TSS, 20, 25 and 30° Brix), SPI: JSS (1:1, 1:3 and 1:5) and NBRE-15 (0.1, 0.2 and 0.3%) were optimized for achieving the most efficient encapsulation of anthocyanin using a three level, three parameter, Box-Behnken design (BBD) of the Design of Experiments (DOE). The responses considered for the optimization were monomeric anthocyanin content, antioxidant activity and encapsulation efficiency. A combination of 27.0% TSS, 1:5 SPI: JSS ratio and 0.3% NBRE-15 was found to be optimum for the encapsulation of anthocyanin with the desirability of 92.6%. Microcapsules obtained using the optimized combination of independent variables was found to contain 3215.59 mg/100 g monomeric anthocyanin. The antioxidant activity and encapsulation efficiency of the encapsulated material obtained using optimized combinations of independent variable were found to be 365.26 µmol Trolox/g and 89.71%, respectively. The microcapsules were also additionally analyzed for the particle size distribution and morphological characterization. Particle size analysis indicated that the microcapsules obtained had a mean particle size of 60.97 µm. Scanning electron microscopy for morphological characterization indicated that the microcapsules so obtained were oval to round in shape and had a smooth surface. Storage studies to estimate the half-life of anthocyanin in the microcapsule at room temperature (37 °C) clearly indicated greater stability i.e. 63 days when stored under amber-colored vial compared to only 35 days when stored under clear transparent vial.


Assuntos
Antocianinas/química , Artocarpus/química , Emulsificantes/química , Pós/química , Sementes/química , Proteínas de Soja/química , Amido/química , Antioxidantes/química , Cápsulas/química , Tamanho da Partícula , Polissacarídeos/química , Temperatura
18.
Int J Biol Macromol ; 163: 209-218, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32615226

RESUMO

This study ascertained the stability of phycobiliprotein (PBP), a bioactive protein from Dulse (Palmaria palmata) loaded within liposomes and stabilized with polyethylene glycol (2000 and 4000 g/mol) and desulfated CNCs (DCs) containing adsorbed polyethylene glycol (DCs-2000 and DCs-4000). The effect of pH, temperature and illumination on the stability of PBP was investigated. Results showed that the temperature had the most significant (p < 0.05) effect on the fluorescence intensity of the PBP, accounting for up to 70% loss of the fluorescence intensity for PBP loaded liposome (PL), PL stabilized with PEG-2000 (PLP-2000) and PEG 4000 (PLP-4000) and PL stabilized with desulfated CNCs (DCs), however, 60% for the PL stabilized with PEG 2000 and PEG 4000 adsorbed CNCs (PLDCs-2000 and PLDCs-4000) at 60 °C compared to those stabilized at 4 °C. A further increase in temperature to 80 °C led to a complete loss of fluorescence. Operating at the extreme pH's of 1.0 and 11.0 resulted in a loss of 90% and 30% fluorescence intensity, respectively for PBP in solution, whereas, 20% and 2% loss was observed for PBP incorporated inside the liposomes. Regarding the effect of illumination, PLDCs-2000 and PLDCs-4000 were the most stable, retaining the fluorescence intensity of PBP up to 70% after 72 h of exposure. This is compared to 85% loss of fluorescence for PBP in solution. Furthermore, at pH of 1.0, there was an increase in average particle size for the PLDCs-2000 and PLDCs-4000 from 189 ± 3 & 206 ± 2 nm to 6464 ± 211 & 6698 ± 317 nm and a charge reversal in the zeta potential from -36 ± 1 & -34 ± 2 to +16 ± 3 & +14 ± 1. Confocal and optical microscopic images confirmed the coalescence of PBP loaded liposome and agglomeration PLDCs-2000 and PLDCs-4000 under acidic pH (<3.0). In contrast, changes in temperature from 4 °C to 100 °C and illumination as a function of time up to 72 h resulted in no change in liposome size and zeta potential.


Assuntos
Celulose/química , Lipossomos/química , Nanopartículas/química , Ficobiliproteínas/química , Polietilenoglicóis/química , Adsorção , Fenômenos Químicos , Concentração de Íons de Hidrogênio , Tamanho da Partícula , Estabilidade Proteica , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura
19.
Sci Rep ; 9(1): 19266, 2019 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-31848376

RESUMO

Study ascertained the recovery of ß-carotene from enzyme-treated (enzyme load of 167 U/g) pericarp of ripe bitter melon using supercritical fluid extraction (SFE) technique. Effect of different pressure (ranged from 150-450 bar), carbon dioxide (CO2) flow rates (ranged from 15 to 55 ml/min), temperatures (from 50 to 90 °C), and extraction periods (from 45-225 minutes) were observed on the extraction efficiency of ß-carotene. Results showed that extraction pressure (X1) among extraction parameters had the most significant (p < 0.05) effect on extraction efficiency of the ß-carotene followed by allowed extraction time (X4), CO2 flow rate (X2) and the temperature of the extraction (X3). The maximum yield of 90.12% of ß-carotene from lyophilized enzymatic pretreated ripe bitter melon pericarp was achieved at the pressure of approx. 390 bar, flow rate of 35 mL/min, temperature at 70 °C and extraction time of 190 min, respectively. Based on the accelerated storage study the 70% retention shelf life of the ß-carotene into extract was estimated up to 2.27 months at 10 °C and up to 3.21 months at 5 °C.


Assuntos
Cromatografia com Fluido Supercrítico , Frutas/química , Momordica charantia/química , beta Caroteno/isolamento & purificação , beta Caroteno/química
20.
Food Chem ; 271: 129-135, 2019 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-30236657

RESUMO

The effect of different processing conditions (B: boiling; F: LAB fermentation; FS: fermentation and steaming; FSF: fermentation, steaming, flaking) of whole grain sorghum on the proximate composition, antioxidants, anti-nutrients, and amino acids (AAs) was evaluated. A marginal increase in the protein content and a decrease in the fat content was observed in the F-sample. Total phenolics reduced by 28%; DPPH scavenging activity and CUPRAC activity increased by 1.4 and 6 times, respectively during fermentation. Tannin content reduced by 30-39%, for the F, FS and FSF samples; highest reduction in trypsin inhibitory activity (58%) was observed in the FS-sample. Total AAs increased by 2.9 folds in FSF samples. Grain sorghum contained mostly hydrophobic AAs (30-34%). The ratio of Essential amino acid to total amino acid and predicted protein efficiency ratio were highest in the F-sample, whereas predicted biological value of the FSF was 3 times than that of the control.


Assuntos
Aminoácidos/análise , Antioxidantes/análise , Manipulação de Alimentos/métodos , Sorghum/química , Taninos/análise , Grão Comestível , Fermentação
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