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1.
J Agric Food Chem ; 68(8): 2506-2515, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-32013414

RESUMO

Thiol groups of cysteine (Cys) residues in proteins react with quinones, oxidation products of polyphenols, to form protein-polyphenol adducts. The aim of the present work was to quantify the amount of adduct formed between Cys residues and 4-methylcatechol (4MC) in minced beef. A Cys-4MC adduct standard was electrochemically synthesized and characterized by liquid chromatography-mass spectrometry (LC-MS) as well as NMR spectroscopy. Cys-4MC adducts were quantified after acidic hydrolysis of myofibrillar protein isolates (MPIs) and LC-MS/MS analysis of meat containing either 500 or 1500 ppm 4MC and stored at 4 °C for 7 days under a nitrogen or oxygen atmosphere. The concentrations of Cys-4MC were found to be 2.2 ± 0.3 nmol/mg MPI and 8.1 ± 0.9 nmol/mg MPI in meat containing 500 and 1500 ppm 4MC, respectively, and stored for 7 days under oxygen. The formation of the Cys-4MC adduct resulted in protein thiol loss, and ca. 62% of the thiol loss was estimated to account for the formation of the Cys-4MC adduct for meat containing 1500 ppm 4MC. Furthermore, protein polymerization increased in samples containing 4MC as evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the polymerization was found to originate from protein-polyphenol interactions as evaluated by a blotting assay with staining by nitroblue tetrazolium.


Assuntos
Cisteína/química , Guaiacol/química , Carne/análise , Fenol/química , Animais , Bovinos , Proteínas Musculares/química , Oxirredução , Quinonas/química , Espectrometria de Massas em Tandem
2.
Food Chem ; 312: 126113, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-31911356

RESUMO

Formation of protein gels in processed muscle foods is one of the most important functionalities. To explore the mechanisms responsible for affecting gel properties of muscle proteins by phosphates, myofibrillar protein (MP) from mantis shrimp (Oratosquilla oratoria) was treated with sodium tripolyphosphate at three pH values (7.0, 8.0, and 9.0). FTIR and UPLC-MS/MS firstly confirmed that phosphate groups were introduced to MP through COP bonds via serine and threonine residues. The incorporation of STP caused increased electronegativity and solubility, more stable α-helix secondary conformation, and reduced tryptophan fluorescence intensity of MP, especially at pH 8.0 and 9.0. These changes led to a finer, ordered and denser three-dimensional gel network microstructure with higher gel strength and elasticity, and water-holding capacity. This study demonstrated that the introduction of phosphate groups could increase negatively charged residues in MP, enhance the crosslinks of proteins through ionic interaction, and promote gel network formation.


Assuntos
Crustáceos , Proteínas Musculares/química , Polifosfatos/química , Animais , Cromatografia Líquida , Elasticidade , Géis/química , Solubilidade , Espectrometria de Massas em Tandem
3.
Ecotoxicol Environ Saf ; 188: 109876, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31704319

RESUMO

This study aimed to assess the levels of pyrethroids and organochlorine residues in the tissues of cultured Mugil capito and in water samples obtained from three different sites (Al-Hamol, Al-Riad and Sidi Salem; referred to as Area 1, Area 2, and Area 3, respectively) in the Delta region, Egypt. The study also assessed the biochemical markers in exposed mullet and evaluated the impact of these residues on the expression of insulin-like growth factor 1 (IGF-1) in muscle and cytochrome P4501A (CYP1A) in liver tissues using qRT-PCR and SDS-PAGE methods. The results revealed that pesticide residue levels in the water were variable, but were lower than detected levels in fish. Significant (P < 0.05) differences were found across the three study areas in terms of serum ALT, but the serum AST level was not significantly (P > 0.05) elevated in all study regions. Serum creatinine and urea levels were significantly (P < 0.05) elevated in area 3. Furthermore, glutathione and malondialdehyde concentrations significantly increased (P < 0.05) in liver tissues in area 3. Using the qRT-PCR technique, the results revealed that the expression level of IGF-1 was most significant in area 3, while the expression level of CYP1A was most significant in area 1. The protein profile showed some differences in band numbers and molecular weights of protein bands across different regions. Overall, the alteration in biochemical parameters revealed pesticide interference with the metabolic processes of fish. Furthermore, the pesticide pollution had an effect on the expression of IGF-1 and CYP1A genes and led to changes in the protein profile. Therefore, these markers can be used to monitor fish distress following exposure to the pollutant.


Assuntos
Família 1 do Citocromo P450/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Hidrocarbonetos Clorados/toxicidade , Fator de Crescimento Insulin-Like I/genética , Proteínas Musculares/metabolismo , Piretrinas/toxicidade , Smegmamorpha/metabolismo , Animais , Aquicultura , Egito , Biomarcadores Ambientais/genética , Hidrocarbonetos Clorados/análise , Hidrocarbonetos Clorados/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Proteínas Musculares/química , Resíduos de Praguicidas/análise , Resíduos de Praguicidas/metabolismo , Resíduos de Praguicidas/toxicidade , Piretrinas/análise , Piretrinas/metabolismo , Alimentos Marinhos/análise , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismo
4.
Food Chem ; 309: 125614, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31678672

RESUMO

Effects of partial substitution of NaCl with KCl, MgCl2 or CaCl2 on oxidative characteristics of myofibrillar protein (MP) in a hydroxyl radical generating system and their heat-induced gel properties were investigated. Results indicated that MP oxidation is dependent upon the different chloride salt types and substitution degree. MP at 0.60 M NaCl was beneficial to protein unfolding and gel quality in the oxidative system. Increased formation of disulfide bonds affected the MP conformation and resulted in a large particle size and an aggregatednetworkofgel at the 50% substitution degree of KCl. The presence of CaCl2 or MgCl2 substitutes contributed to protein polymerization and insolubility. MP aggregation restrained the formation of dense and continuous gel networks during heating, and thus resulted in a low-grade gel. Ca2+ had more serious impact on gel properties than Mg2+, dependent on different cation effects. Substitution of 25% NaCl by KCl gave acceptable gel quality in MP.


Assuntos
Manipulação de Alimentos/métodos , Proteínas Musculares/química , Cloreto de Potássio/química , Cloreto de Sódio/química , Animais , Cloreto de Cálcio/química , Dissulfetos/química , Géis/química , Radical Hidroxila/química , Cloreto de Magnésio/química , Oxirredução , Tamanho da Partícula , Desdobramento de Proteína
5.
J Sci Food Agric ; 100(1): 119-128, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31441054

RESUMO

BACKGROUND: T-2 toxin (T-2) is a potent mycotoxin and a common contaminant of aquatic animal feed, posing a serious risk to health and aquatic animals. We investigated the effect of T-2 on shrimp muscle proteins using proteomics and conventional biochemical methods. Shrimp were fed a diet containing T-2 at 0-12.2 mg kg-1 for 20 days, and changes to the muscle protein composition, ATPase activities, and the sulfhydryl (SH) content and hydrophobicity of actomyosin (AM) were determined. A proteomics study of the proteins was conducted with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional (2D) electrophoresis, and matrix-assisted laser desorption/ionization - time of flight mass spectrometry (MALDI-TOF/TOF MS). RESULTS: Exposure to T-2 markedly affected the muscle protein composition of shrimp in a concentration-responsive manner that displayed a diphasic effect. At a low T-2 concentration (1.2 mg kg-1 ), the levels of three major muscle proteins (myofibrillar, sarcoplasmic, and stroma) increased but at higher concentrations they declined progressively. T-2 exposure also led to a breakdown of muscle proteins as evidenced by increases in alkali-soluble protein and the surface hydrophobicity (SoANS) of AM. Thirty differentially expressed proteins were detected, 12 of which showed a concentration-response relationship with T-2 exposure. Among them, 11 homologous proteins were identified by mass spectrometry (MS), with several being key enzymes in energy metabolism. CONCLUSION: This study demonstrated that T-2 exposure at medium to high concentrations could significantly affect the protein composition and quality of shrimp muscle, and potentially some of its key metabolisms. One of the arginine kinases (spot 27) was particularly responsive to T-2 and could potentially be used as a biomarker protein for T-2 intoxication by shrimp. © 2019 Society of Chemical Industry.


Assuntos
Proteínas Musculares/química , Penaeidae/efeitos dos fármacos , Frutos do Mar/análise , Toxina T-2/toxicidade , Ração Animal/análise , Animais , Eletroforese em Gel de Poliacrilamida , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Músculos/química , Músculos/efeitos dos fármacos , Músculos/metabolismo , Penaeidae/química , Penaeidae/genética , Penaeidae/metabolismo , Proteômica , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
6.
J Sci Food Agric ; 100(1): 258-267, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31512250

RESUMO

BACKGROUND: Composite gels were individually prepared from 20 g kg-1 myofibrillar protein (MP) imbedded with typical native starch (potato, tapioca, rice or corn starch) in 0.6 mol L-1 NaCl at pH 6.2. The gel strength, water holding capacity, rheological properties and microstructure of the obtained myofibrillar protein-starch composite gels were evaluated. RESULTS: Tapioca starch improved (P < 0.05) gel strength and water holding capacity of MP composite gel at 80 °C. Rheological properties of MP-starch composites differed significantly with the addition of different types of native starch. Additionally, the promoting effect of starch on the storage modulus of the composite gels positively correlated with the gelatinization properties of different typical starch. Environmental scanning electron microscopy showed that the filling effect of starch on the composite gel was related to the pasting temperature and particle size of typical starch, with almost no particles forming at 80 °C. Moreover, the addition of starch changed the relaxation peak area and increased the relaxation time in nuclear magnetic resonance tests, which suggested that starch could improve the water holding capacity of MP-starch composite gels. CONCLUSION: Different typical native starch has varied impacts on the gel strength, water holding capacity, rheological properties and microstructure of MP gels, indicating the potential and feasibility of these typical native starches as an addition agent to modify the textural properties in comminuted meat products. © 2019 Society of Chemical Industry.


Assuntos
Produtos da Carne/análise , Proteínas Musculares/química , Miofibrilas/química , Extratos Vegetais/química , Amido/química , Animais , Aditivos Alimentares/química , Géis/química , Espectroscopia de Ressonância Magnética , Manihot/química , Oryza/química , Reologia , Solanum tuberosum/química , Suínos , Zea mays/química
7.
J Sci Food Agric ; 100(2): 551-559, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31587285

RESUMO

BACKGROUND: Phosphorylation is one of the most important post-translational modifications. Currently, many postmortem protein phosphorylation studies in muscle have been related to meat quality such as tenderness and color stability. However, the effects of various storage temperatures (25, 15, 4 and -1.5 °C) on the phosphorylation level of protein are poorly understood. Changes in the protein phosphorylation levels in postmortem ovine muscle at various storage temperatures were determined in this study. RESULTS: The obtained data showed that pH decline rate was significantly inhibited at -1.5 °C from 12 h to 7 days postmortem (P < 0.05). The ATP consumption rate was higher at 25 °C than that at other three temperatures (P < 0.05). Analysis of the temperature, pH and ATP content revealed that the ATP content was related to the phosphorylation levels of individual protein bands. Phosphorylated myofibrillar and sarcoplasmic proteins, such as myosin binding protein C, troponin T3, myosin light chain 1, glucose-6-phosphate isomerase and pyruvate kinase, were mainly involved in glycolysis and muscle contraction. CONCLUSION: The global and specific protein phosphorylation levels can be influenced by the postmortem storage temperature of muscle. Phosphorylation of proteins was correlated with glycolysis and muscle contraction. Certain phosphorylated proteins, such as heat shock proteins, require further study to clarify their effects on meat traits. © 2019 Society of Chemical Industry.


Assuntos
Armazenamento de Alimentos/métodos , Carne/análise , Proteínas Musculares/química , Músculo Esquelético/química , Animais , Armazenamento de Alimentos/instrumentação , Glicólise , Fosforilação , Mudanças Depois da Morte , Ovinos , Temperatura Ambiente
8.
Meat Sci ; 160: 107973, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31655245

RESUMO

This experiment was designed to evaluate the influence of mulberry polyphenols (MP) on oxidation stability of sarcoplasmic and myofibrillar proteins in dried minced pork slice during processing and storage. Composition, amino acid side chain modification, average particle size, hydrophobicity and solubility of proteins in the slices were investigated. MP displayed protective effects on oxidation stability of sarcoplasmic and myofibrillar proteins in slices, considering carbonyl formation and transformation from SH group to SS group were remarkably retarded by MP. Proteins in MP-treated slices possessed larger average particle size but lower aggregation during processing and storage. Meanwhile, the strengthened ionic bonds and weakened hydrogen, hydrophobic and disulfide bond could be responsible for the improved protein stability of slice with MP. All these results suggested that mulberry polyphenol could improve protein oxidation stability in meat products.


Assuntos
Produtos da Carne/análise , Proteínas Musculares/química , Polifenóis/química , Animais , Manipulação de Alimentos/métodos , Armazenamento de Alimentos , Morus/química , Miofibrilas/química , Oxirredução , Suínos
9.
Nat Commun ; 10(1): 4910, 2019 10 28.
Artigo em Inglês | MEDLINE | ID: mdl-31659163

RESUMO

AspH is an endoplasmic reticulum (ER) membrane-anchored 2-oxoglutarate oxygenase whose C-terminal oxygenase and tetratricopeptide repeat (TPR) domains present in the ER lumen. AspH catalyses hydroxylation of asparaginyl- and aspartyl-residues in epidermal growth factor-like domains (EGFDs). Here we report crystal structures of human AspH, with and without substrate, that reveal substantial conformational changes of the oxygenase and TPR domains during substrate binding. Fe(II)-binding by AspH is unusual, employing only two Fe(II)-binding ligands (His679/His725). Most EGFD structures adopt an established fold with a conserved Cys1-3, 2-4, 5-6 disulfide bonding pattern; an unexpected Cys3-4 disulfide bonding pattern is observed in AspH-EGFD substrate complexes, the catalytic relevance of which is supported by studies involving stable cyclic peptide substrate analogues and by effects of Ca(II) ions on activity. The results have implications for EGFD disulfide pattern processing in the ER and will enable medicinal chemistry efforts targeting human 2OG oxygenases.


Assuntos
Proteínas de Ligação ao Cálcio/química , Proteínas de Membrana/química , Oxigenases de Função Mista/química , Proteínas Musculares/química , Sequência de Aminoácidos , Asparagina/metabolismo , Proteínas de Ligação ao Cálcio/genética , Proteínas de Ligação ao Cálcio/metabolismo , Domínio Catalítico , Cristalografia , Dissulfetos/química , Dissulfetos/metabolismo , Fator de Crescimento Epidérmico/metabolismo , Compostos Ferrosos/química , Compostos Ferrosos/metabolismo , Humanos , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Oxigenases de Função Mista/genética , Oxigenases de Função Mista/metabolismo , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Conformação Proteica
10.
Molecules ; 24(18)2019 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-31500282

RESUMO

The present study investigated the antioxidant potential and the ability to inhibit lipid and protein oxidation in bovine meat of four native Chilean species: canelo (Drimys winteri), nalca (Gunnera tinctoria), tiaca (Caldcluvia paniculata), and ulmo (Eucryphia cordifolia). Phenolic acids (gallic, chlorogenic, caffeic, and coumaric) and flavonoids (catechin, epicatechin, and rutin) were identified and quantified by HPLC-MS/MS. Drimys winteri extract exhibited the highest antioxidant capacity evaluated by oxygen radical absorption capacity-red pyrogallol method (ORAC-PGR) and ferric ion reducing antioxidant power (FRAP) assays. All extracts decreased lipid oxidation induced by 2,2'-azo-bis(2-amidinopropane) dihydrochloride (AAPH) derived peroxyl radicals by anywhere between 30% and 50% the. In addition, canelo and nalca extracts decreased spontaneous oxidation by around 57% and 37% in relation to the control group, being even more efficient than butylated hydroxyanisole (BHT) a synthetic antioxidant. Protein oxidation in the myofibrillar proteins was evaluated by the formation of protein carbonyls and loss of protein thiols. The canelo, ulmo, and nalca extracts decreased the formation of carbonyls by around 30%. Plant extracts and BHT did not show an antioxidant effect on protein thiol loss. However, tiaca and ulmo extracts exerted a pro-oxidant effect, favoring the oxidation of sulfhydryl groups. The oxidizing system induced structural changes in myofibrillar protein (SDS-PAGE). A protective effect on protein structure from the canelo extract can be observed during the incubation when compared to samples incubated with AAPH.


Assuntos
Antioxidantes/farmacologia , Peroxidação de Lipídeos/efeitos dos fármacos , Magnoliopsida/química , Proteínas Musculares/química , Animais , Antioxidantes/química , Bovinos , Flavonoides/química , Flavonoides/farmacologia , Hidroxibenzoatos/química , Hidroxibenzoatos/farmacologia , Componentes Aéreos da Planta/química , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Folhas de Planta/química
11.
Food Funct ; 10(10): 6568-6581, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31552989

RESUMO

Formation of a gel matrix, involving interactions between proteins, lipids, and water, plays an essential role in the textural properties of processed meats. This study investigated the effects of sodium pyrophosphate (SPP) on the textural properties and oxidative stability of myofibrillar protein (MP)-stabilized emulsion gels under different pH conditions (5.0-9.0). The SPP-modified MP emulsion gels showed an improved elasticity, strength, water-holding capacity, and oxidative stability at pH 6.0 and 7.0. This improvement should be mainly attributed to the enhanced protein-protein crosslinks via ionic interaction between phosphate groups and -NH3+ of amino acids, which were homogeneously formed among adsorbed and/or unadsorbed proteins, entrapping fractions of MPs (myosin heavy chain, actin, and troponin T) within the network. Therefore, the oil droplets were better adherent to the gel matrix. Nevertheless, increased electrostatic repulsion between protein molecules due to excessive phosphates attached to MPs at pH 8.0 and 9.0, as well as protein precipitation at pH 5.0, caused the collapse of the MP-stabilized emulsion gel structure, and thus, overall decreased the gel properties and oxidative stability. LC-MS/MS results confirmed that phosphate groups were successfully introduced to MPs through C-O-P bonds at pH 6.0, and the phosphorylation sites were found to be on serine residues (Ser14, Ser79, Ser96, Ser148, Ser2427, and Ser5272), threonine residues (Thr118 and Thr926), and tyrosine residues (Tyr215 and Tyr425). The results provided a new aspect for better understanding the effect of polyphosphates in meat protein/oil composite systems.


Assuntos
Produtos da Carne/análise , Proteínas Musculares/química , Animais , Galinhas , Difosfatos/química , Emulsões/química , Géis/química , Concentração de Íons de Hidrogênio , Miofibrilas/química , Oxirredução , Fosforilação
12.
Food Chem ; 301: 125278, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31387033

RESUMO

Softening is always a problem in fish preservation. This study was aimed to investigate the role of myofibrillar structural proteins degradation in fish softening. The changes of myofibrillar structural proteins, muscle ultrastructure, myofibril fragmentation, and shear force were studied. The results indicated that during the superchilled preservation of grass carp (Ctenopharyngodon idella), small (low-molecular-weight) myofibrillar structural proteins like desmin and troponin-T initiated textural deterioration, leading to Z-disk weakening and actin loosening. In contrast, giant (high-molecular-weight) myofibrillar structural proteins like titin and nebulin were degraded in more amount in the later storage, contributing to Z-disk and M-band disassembly and vague of light and dark regions (I and A bands). Compared to each other, desmin and titin played more important part in softening. All these changes were involved in the increase of muscle fibril segments and the sharp decrease of shear force.


Assuntos
Carpas/metabolismo , Produtos Pesqueiros , Proteínas de Peixes/química , Miofibrilas/química , Animais , Conectina/química , Conectina/metabolismo , Desmina/química , Desmina/metabolismo , Proteínas de Peixes/metabolismo , Proteínas Musculares/química , Proteínas Musculares/metabolismo , Miofibrilas/metabolismo , Proteólise , Troponina T/química , Troponina T/metabolismo
13.
Gene ; 716: 144036, 2019 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-31381952

RESUMO

Nebulin is a 770 kDa protein that is localized along the thin filaments of skeletal muscles in vertebrates. It is also present in the striated muscles of Amphioxus, an invertebrate cephalochordate that is phylogenetically close to vertebrates. However, the nebulin of urochordate ascidians or its expression in invertebrate hearts has not been investigated. In this study, we investigated the structure and cardiac expression of the nebulin gene in Ciona intestinalis, a urochordate whose phylogeny lies between cephalochordates and vertebrates. As a result of the gene structure analysis, we found that the Ciona nebulin gene predicted to be 62 kb and consists of 143 exons. The nebulin was expected to consist of a unique N-terminal region, followed by 155 nebulin repeats, another unique region, a Ser-rich region and a C-terminal SH3 domain. Whole-mount in situ hybridization experiments showed that the Ciona nebulin gene was expressed in a variety of muscles, including hearts. However, Western blot analysis using antibody to Ciona nebulin did not detect the presence of full-length nebulin. Alternatively, RT-PCR experiments on samples of Ciona heart detected the expression of nebulette-like and nrap-like isoforms from the Ciona nebulin gene. These results indicate that, similarly to vertebrate hearts, Ciona hearts do not express nebulin, but rather nrap- and nebulette-like isoforms. These results also imply that the nebulin, nebulette and nrap genes in vertebrates were separated from an ancestral invertebrate nebulin gene during vertebrate evolution.


Assuntos
Ciona intestinalis/genética , Família Multigênica , Proteínas Musculares/genética , Miocárdio/metabolismo , Animais , Ciona intestinalis/metabolismo , Evolução Molecular , Éxons , Íntrons , Proteínas Musculares/química , Proteínas Musculares/metabolismo , Domínios Proteicos , RNA Mensageiro/metabolismo
14.
Food Chem ; 301: 125206, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31377630

RESUMO

Effects of different levels of rutin (0, 10, 50, 100 and 200 µmol/g protein) on the conformational changes and gel properties of myofibrillar protein (MP) were investigated. Rutin at 200 µmol/g caused the greatest carbonyl content. The incorporation of rutin caused the losses of thiol, free amine and α-helix contents, reduction in tryptophan intrinsic fluorescence intensity, and enhanced exposure of hydrophobic groups and protein cross-linking. When compared with control, the MP gels with 10, 50 and 100 µmol/g rutin had higher gel strength but slight lower water-holding capacity; the gels appeared to have compact microstructure with few visible pores. However, 200 µmol/g rutin was detrimental to gel properties. All the gels with rutin presented higher final storage modulus and converted to elasticity-dominant gel types. The results indicate that a slightly high concentration of rutin could improve MP gel properties which are related to the protein conformational changes induced by rutin.


Assuntos
Proteínas Musculares/química , Miofibrilas/química , Rutina/química , Elasticidade , Géis/química , Interações Hidrofóbicas e Hidrofílicas , Conformação Proteica , Carne Vermelha , Espectrometria de Fluorescência , Triptofano/química , Água/química
15.
Oxid Med Cell Longev ; 2019: 7318796, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31428229

RESUMO

Ankrd2 (ankyrin repeats containing domain 2) or Arpp (ankyrin repeat, PEST sequence, and proline-rich region) is a member of the muscle ankyrin repeat protein family. Ankrd2 is mostly expressed in skeletal muscle, where it plays an intriguing role in the transcriptional response to stress induced by mechanical stimulation as well as by cellular reactive oxygen species. Our studies in myoblasts from Emery-Dreifuss muscular dystrophy 2, a LMNA-linked disease affecting skeletal and cardiac muscles, demonstrated that Ankrd2 is a lamin A-binding protein and that mutated lamins found in Emery-Dreifuss muscular dystrophy change the dynamics of Ankrd2 nuclear import, thus affecting oxidative stress response. In this review, besides describing the latest advances related to Ankrd2 studies, including novel discoveries on Ankrd2 isoform-specific functions, we report the main findings on the relationship of Ankrd2 with A-type lamins and discuss known and potential mechanisms involving defective Ankrd2-lamin A interplay in the pathogenesis of muscular laminopathies.


Assuntos
Proteínas Musculares/metabolismo , Músculo Esquelético/metabolismo , Distrofia Muscular de Emery-Dreifuss/patologia , Proteínas Nucleares/metabolismo , Estresse Oxidativo , Proteínas Repressoras/metabolismo , Humanos , Lamina Tipo A/metabolismo , Mecanotransdução Celular , Proteínas Musculares/química , Distrofia Muscular de Emery-Dreifuss/metabolismo , Miocárdio/metabolismo , Proteínas Nucleares/química , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Proteínas Repressoras/química
16.
J Sci Food Agric ; 99(14): 6462-6473, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31298738

RESUMO

BACKGROUND: Biochemical and protein conformational changes in silver carp occurred during ice storage, affecting the physico-chemical and textural properties of its washed mince. Fourier-transform infrared spectroscopy (FTIR) and FT Raman could offer insightful molecular-level information that could be related to the freshness of fish and textural properties of washed mince. RESULTS: The K value increased from 15.8% to 85.0% after 14 days on ice. The surface hydrophobicity of silver carp muscle proteins increased during ice storage, and its thrice-washed mince showed the same trend. The yield and textural properties of washed mince continually decreased as the storage time was extended. Fourier-transform infrared spectroscopy revealed that, as storage time increased, the α-helix content of mince decreased, while the ß sheet content increased. Prolonged ice storage led to the exposure of buried aromatic amino acid residues and an increase in disulfide interchanges in mince and washed mince. Changes in the ∑ß sheet structure and Raman intensity at 828 cm-1 observed in mince correlated well with the K value. The α-helix content and Raman intensity of raw washed mince at 621 and 828 cm-1 showed a strong correlation with its textural properties. CONCLUSION: Silver carp should be processed to surimi within 7 days of ice storage to obtain a reasonably good yield and gel texture. Infrared and Raman spectroscopy can possibly be utilized to monitor freshness quality and protein conformational changes in silver carp and to estimate the textural properties of washed mince as affected by freshness. © 2019 Society of Chemical Industry.


Assuntos
Produtos Pesqueiros/análise , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Análise Espectral Raman/métodos , Animais , Carpas , Proteínas de Peixes/química , Interações Hidrofóbicas e Hidrofílicas , Proteínas Musculares/química , Controle de Qualidade
17.
Food Chem ; 298: 125060, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31261004

RESUMO

Typical ketone flavours (with variations in chain length, position and number of keto group, branched chain) were selected to investigate the effect of molecule structure of ketones on their interactions with myofibrillar proteins (MPs). Results showed that 2,3-pentanedione quenched the fluorescence of MPs more effectively than 2-pentanone and 3-pentanone due to the number of keto group. There was no significant difference between 5-methyl-2-hexanone and 2-heptanone, which was attributed to their similar molecular size and polarity. The quenching effect of homologous ketone flavours increased with carbon chain growth due to the higher hydrophobic interaction. Dynamic quenching played a major role in the fluorescence quenching process of MPs by 2-pentanone, 3-pentanone, 5-methyl-2-hexanone, 2-heptanone and 2-octanone. The α-helix content decreased gradually with the increase of ketones concentration. Results of GC/MS were in accordance with the fluorescence quenching analysis generally, whereas 2,3-pentanedione and 2-nonanone exhibited some differences due to their higher steric hindrance effects.


Assuntos
Aromatizantes/química , Cetonas/química , Proteínas Musculares/química , Animais , Dicroísmo Circular , Aromatizantes/análise , Aromatizantes/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Cetonas/metabolismo , Proteínas Musculares/metabolismo , Ligação Proteica , Microextração em Fase Sólida , Espectrometria de Fluorescência , Suínos
18.
J Sci Food Agric ; 99(14): 6500-6508, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31321768

RESUMO

BACKGROUND: Emulsification is important for food quality and processing functionality. Most emulsification occurs under high-fat conditions that eventually cause health concerns. Protein emulsifiers also have drawbacks such as lower dispersity. This study considered the effects of different high-speed shear homogenization (HSH) speeds on the emulsifying and structural properties of myofibrillar proteins (MPs) under low-fat conditions. RESULTS: High-speed shear homogenization significantly increased the emulsifying activity and emulsifying stability of MPs at lower speeds (8000 to 14 500 rpm). The primary structure of MP was not altered significantly by HSH, whereas its secondary, tertiary, and quaternary structures were changed. Particle size decreased first and then increased significantly, and reached a minimum when the HSH speed was 14 500 rpm. The absolute zeta potential values increased significantly and the dendritic fibrous structure of sample was destroyed when the speed exceeded 14 500 rpm. High-speed shear homogenization (14 500 rpm) decreased the particle size and unfolded the protein, which improved the emulsifying properties of MPs. Excessive HSH speeds (20 500 rpm or higher) caused an aggregation of MP molecules, which was not conducive to improving their emulsifying properties. CONCLUSION: Optimal HSH speed was achieved at 14 500 rpm to modify MPs' emulsifying and structural properties under low-fatconditions. © 2019 Society of Chemical Industry.


Assuntos
Gorduras/análise , Manipulação de Alimentos/métodos , Proteínas Musculares/química , Animais , Galinhas , Emulsões/química , Emulsões/isolamento & purificação , Manipulação de Alimentos/instrumentação , Carne/análise , Proteínas Musculares/isolamento & purificação , Tamanho da Partícula , Pressão , Dobramento de Proteína
19.
Int J Biol Macromol ; 138: 425-432, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31326511

RESUMO

The present work investigated effects of high-pressure homogenization (HPH) pressure (0, 40, 80 and 120 MPa) on physicochemical, functional and rheological properties of clam myofibrillar protein (CMP). Results showed that HPH changed the CMP secondary and tertiary structures. Absolute zeta potential and protein solubility increased but particle size and turbidity of CMP decreased after HPH treatment. Both of emulsifying properties and foaming properties were significantly improved. The shear stress, apparent viscosity and the viscosity coefficients reduced, but flow index increased. Application of HPH improved the physicochemical, functional and rheological properties of CMP, and 120 MPa was the optimal pressure for modification.


Assuntos
Fenômenos Químicos , Proteínas Musculares/química , Miofibrilas/química , Pressão , Reologia , Interações Hidrofóbicas e Hidrofílicas , Fenômenos Mecânicos , Tamanho da Partícula , Solubilidade , Análise Espectral , Viscosidade
20.
Food Chem ; 299: 125104, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31279125

RESUMO

The role of protein denaturation in formation of thaw loss is currently not well understood. This study investigated denaturation of myofibrillar and sarcoplasmic proteins of pork loins caused by freezing-thawing in relation to freezing rate. Compared to fast freezing, slow freezing caused 28% larger thaw loss, decreased water-holding capacity of myofibrils and increased surface hydrophobicity, indicating more pronounced denaturation of myofibrillar proteins. We here propose a model: In slow freezing protons are concentrated in the unfrozen water resulting in reduced pH in proximity of structural proteins causing protein denaturation. In parallel, large ice crystals are formed outside of muscle fibers resulting in transversal shrinkage. In fast freezing small ice crystals trap protons and cause less severe protein denaturation and reduced thaw loss. Differential scanning calorimetry and tryptophan fluorescence spectra indicated sarcoplasmic protein denaturation in drip due to freezing-thawing. However, sarcoplasmic protein denaturation was independent of freezing rate.


Assuntos
Congelamento , Proteínas Musculares/química , Miofibrilas/química , Desnaturação Proteica , Carne Vermelha , Animais , Varredura Diferencial de Calorimetria , Conservação de Alimentos/métodos , Interações Hidrofóbicas e Hidrofílicas , Gelo , Músculos Paraespinais/química , Carne Vermelha/análise , Espectrometria de Fluorescência , Triptofano/química , Água/química
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