Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.186
Filtrar
1.
Food Chem ; 308: 125576, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-31648092

RESUMO

This study investigated the effects of cold storage at different temperatures (4, -0.5, -3, and -20 °C) on protein degradation and its relationship to structural changes of black carp muscle. At -0.5 and 4 °C, major structural changes occurred, including the formation of gaps between myofibers and myofibrils, breakage of myofibrils and myofibers, and degradation of sarcoplasmic reticulum. Gel-based proteomic analysis showed that these structural changes were accompanied by degradation of a series of myofibrillar proteins, including titin, nebulin, troponin, myosin, myomesin, myosin-binding protein, and α-actinin. Loss of extractable gelatinolytic and caseinolytic protease activities was also observed. At -3 and -20 °C, formation of ice crystals was the most noticeable change. The major proteins were degraded at different locations in the black carp muscle, and gelatinolytic and caseinolytic proteases appear to contribute to the degradation of those proteins.


Assuntos
Carpas/metabolismo , Actinina/metabolismo , Animais , Proteínas de Transporte , Temperatura Baixa , Conectina/metabolismo , Cyprinidae/metabolismo , Proteínas Musculares/metabolismo , Miofibrilas/metabolismo , Miosinas/metabolismo , Proteólise , Proteômica
2.
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
3.
Insect Biochem Mol Biol ; 114: 103226, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31446033

RESUMO

The huge energy demand posed by insect flight activity is met by an efficient oxidative phosphorylation process that takes place within flight muscle mitochondria. In the major arbovirus vector Aedes aegypti, mitochondrial oxidation of pyruvate, proline and glycerol 3-phosphate (G3P) represent the major energy sources of ATP to sustain flight muscle energy demand. Although adenylates exert critical regulatory effects on several mitochondrial enzyme activities, the potential consequences of altered adenylate levels to G3P oxidation remains to be determined. Here, we report that mitochondrial G3P oxidation is controlled by adenylates through allosteric regulation of cytochrome c oxidase (COX) activity in A. aegypti flight muscle. We observed that ADP significantly activated respiratory rates linked to G3P oxidation, in a protonmotive force-independent manner. Kinetic analyses revealed that ADP activates respiration through a slightly cooperative mechanism. Despite adenylates caused no effects on G3P-cytochrome c oxidoreductase activity, COX activity was allosterically activated by ADP. Conversely, ATP exerted powerful inhibitory effects on respiratory rates linked to G3P oxidation and on COX activity. We also observed that high energy phosphate recycling mechanisms did not contribute to the regulatory effects of adenylates on COX activity or G3P oxidation. We conclude that mitochondrial G3P oxidation in A. aegypti flight muscle is regulated by adenylates through the allosteric modulation of COX activity, underscoring the bioenergetic relevance of this novel mechanism and the potential consequences for mosquito dispersal.


Assuntos
Aedes/metabolismo , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Glicerofosfatos/metabolismo , Mitocôndrias/metabolismo , Miofibrilas/metabolismo , Regulação Alostérica , Animais , Respiração Celular , Feminino , Oxirredução
4.
Nutrients ; 11(7)2019 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-31331099

RESUMO

The aim of this study was to test the effects of two disparate isonitrogenous, isocaloric pre-exercise feeds on deuterium-oxide (D2O) derived measures of myofibrillar protein synthesis (myoPS) in humans. Methods: In a double-blind parallel group design, 22 resistance-trained men aged 18 to 35 years ingested a meal (6 kcal·kg-1, 0.8 g·kg-1 carbohydrate, 0.2 g·kg-1 fat) with 0.33 g·kg-1 nonessential amino acids blend (NEAA) or whey protein (WHEY), prior to resistance exercise (70% 1RM back-squats, 10 reps per set to failure, 25% duty cycle). Biopsies of M. vastus lateralis were obtained pre-ingestion (PRE) and +3 h post-exercise (POST). The myofibrillar fractional synthetic rate (myoFSR) was calculated via deuterium labelling of myofibrillar-bound alanine, measured by gas chromatography-pyrolysis-isotope ratio mass spectrometry (GC-Pyr-IRMS). Data are a mean percentage change (95% CI). Results: There was no discernable change in myoFSR following NEAA (10(-5, 25) %, p = 0.235), whereas an increase in myoFSR was observed after WHEY (28 (13, 43) %, p = 0.003). Conclusions: Measured by a D2O tracer technique, a disparate myoPS response was observed between NEAA and WHEY. Pre-exercise ingestion of whey protein increased post-exercise myoPS, whereas a NEAA blend did not, supporting the use of NEAA as a viable isonitrogenous negative control.


Assuntos
Aminoácidos/administração & dosagem , Exercício/fisiologia , Proteínas Musculares/biossíntese , Miofibrilas/metabolismo , Proteínas do Soro do Leite/administração & dosagem , Adolescente , Adulto , Aminoácidos/sangue , Aminoácidos Essenciais/administração & dosagem , Aminoácidos Essenciais/sangue , Método Duplo-Cego , Humanos , Masculino , Biossíntese de Proteínas/efeitos dos fármacos , Treinamento de Resistência , Adulto Jovem
5.
Biomed Pharmacother ; 116: 109046, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31174091

RESUMO

This study was conducted to purify the angiotensin converting enzyme (ACE) inhibitory peptides from beef myofibrillar proteins by using inexpensive enzymes alkaline-AK and papain. Different molecular weight peptides (<3 and <10 kDa) were obtained using ultrafiltration. The <3 kDa peptides obtained by alkaline-AK (AK3K) digestion showed the highest ACE inhibitory activity (74.29%) as compared to other alkaline-AK peptides, and a strong antihypertensive effect of AK3K was observed in the spontaneously hypertensive rat (SHR) model. The AK3K treatment groups (400 and 800 mg/kg body weight) exhibited a decrease in systolic blood pressure (SBP) by 28 and 35 mmHg, respectively in the SHR model. The study demonstrated that the ACE inhibitory peptide obtained from beef myofibrillar proteins had the sequence Leu-Ile-Val-Gly-Ile-Ile-Arg-Cys-Val, and could be possibly used for lowering the SBP.


Assuntos
Inibidores da Enzima Conversora de Angiotensina/isolamento & purificação , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Proteínas Musculares/metabolismo , Miofibrilas/metabolismo , Peptídeos/isolamento & purificação , Peptídeos/uso terapêutico , Carne Vermelha , Sequência de Aminoácidos , Animais , Anti-Hipertensivos/farmacologia , Anti-Hipertensivos/uso terapêutico , Peso Corporal/efeitos dos fármacos , Modelos Animais de Doenças , Especificidade de Órgãos , Oxirredução , Peptídeos/química , Ratos Endogâmicos SHR , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo
6.
Food Chem ; 295: 520-529, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31174791

RESUMO

This study aimed to investigate the effect of stunning stress on textural properties and water-holding capacity (WHC) of silver carp (Hypophthalmichthys molitrix) fillets and its underlying mechanisms based on intrinsic proteases activity, myofibril microstructure, and myowater dynamic measurements. The results suggested that compared with the non-stressful percussion, ice/water and gill cut stunning resulted in accelerated muscle tenderization with intensive myofibril disintegration and sarcolemma-myofibril detachments. Myowater mobility and distribution were altered by stunning stress, in which gill cut facilitated the migration of immobilized water and free water, thus enhancing the centrifugation loss. In addition, stunning stress promoted the activation of endogenous proteases and the release of cathepsin B and L from lysosomes to myofibrils, which showed significant (P < 0.01) correlations with decreased shear force and elevated myofibril fragmentation index of fillets. Therefore, faster accumulation of cathepsins and myofibril disintegration together contributed to the weakening of texture and WHC in stunning-stressed fish fillets.


Assuntos
Alimentos Marinhos/análise , Animais , Carpas , Catepsina B/metabolismo , Catepsina L/metabolismo , Lisossomos/enzimologia , Espectroscopia de Ressonância Magnética , Miofibrilas/metabolismo , Miofibrilas/ultraestrutura , Resistência ao Cisalhamento , Estresse Fisiológico , Água/química , Água/metabolismo
7.
J Biol Chem ; 294(18): 7219-7220, 2019 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-31053679

RESUMO

"Myosin" is famous as a component of muscle fibrils, but the majority of myosin family members act elsewhere with roles unrelated to muscle contraction. The biological functions of a relatively new family of these unconventional myosins, myosins 18A and 18B, are poorly understood. New research from Horsthemke et al. describes a new isoform (Myo18Aγ) that is essential for heart function and viability in mice. Their findings both support and contradict other work in the field and raise new questions about the roles of myosin 18 proteins in vivo.


Assuntos
Miofibrilas/metabolismo , Miosinas/metabolismo , Animais , Citoesqueleto/metabolismo , Camundongos
8.
Genetics ; 212(3): 743-755, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31123042

RESUMO

Alp/Enigma family members have a unique PDZ domain followed by zero to four LIM domains, and are essential for myofibril assembly across all species analyzed so far. Drosophila melanogaster has three Alp/Enigma family members, Zasp52, Zasp66, and Zasp67. Ortholog search and phylogenetic tree analysis suggest that Zasp genes have a common ancestor, and that Zasp66 and Zasp67 arose by duplication in insects. While Zasp66 has a conserved domain structure across orthologs, Zasp67 domains and lengths are highly variable. In flies, Zasp67 appears to be expressed only in indirect flight muscles, where it colocalizes with Zasp52 at Z-discs. We generated a CRISPR null mutant of Zasp67, which is viable but flightless. We can rescue all phenotypes by re-expressing a Zasp67 transgene at endogenous levels. Zasp67 mutants show extended and broken Z-discs in adult flies, indicating that the protein helps stabilize the highly regular myofibrils of indirect flight muscles. In contrast, a Zasp66 CRISPR null mutant has limited viability, but only mild indirect flight muscle defects illustrating the diverging evolutionary paths these two paralogous genes have taken since they arose by duplication.


Assuntos
Proteínas de Transporte/genética , Proteínas de Drosophila/genética , Evolução Molecular , Proteínas Musculares/genética , Miofibrilas/metabolismo , Animais , Proteínas de Transporte/metabolismo , Sequência Conservada , Proteínas de Drosophila/metabolismo , Drosophila melanogaster , Duplicação Gênica , Proteínas Musculares/metabolismo , Miofibrilas/ultraestrutura , Fenótipo
9.
Anim Sci J ; 90(7): 801-807, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31134719

RESUMO

Skeletal muscle consists of bundles of myofibers containing millions of myofibrils, each of which is formed of longitudinally aligned sarcomere structures. Sarcomeres are the minimum contractile unit, which mainly consists of four components: Z-bands, thin filaments, thick filaments, and connectin/titin. The size and shape of the sarcomere component is strictly controlled. Surprisingly, skeletal muscle cells not only synthesize a series of myofibrillar proteins but also regulate the assembly of those proteins into the sarcomere structures. However, authentic sarcomere structures cannot be reconstituted by combining purified myofibrillar proteins in vitro, therefore there must be an elaborate mechanism ensuring the correct formation of myofibril structure in skeletal muscle cells. This review discusses the role of myosin, a main component of the thick filament, in thick filament formation and the dynamics of myosin in skeletal muscle cells. Changes in the number of myofibrils in myofibers can cause muscle hypertrophy or atrophy. Therefore, it is important to understand the fundamental mechanisms by which myofibers control myofibril formation at the molecular level to develop approaches that effectively enhance muscle growth in animals.


Assuntos
Citoesqueleto/metabolismo , Músculo Esquelético/citologia , Músculo Esquelético/metabolismo , Miosinas/fisiologia , Animais , Atrofia , Hipertrofia , Músculo Esquelético/crescimento & desenvolvimento , Músculo Esquelético/patologia , Miofibrilas/metabolismo , Miofibrilas/patologia , Miosinas/metabolismo , Sarcômeros/metabolismo
10.
Food Chem ; 294: 316-325, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31126469

RESUMO

The present study studied the effects of fish gelatin (FG) incorporated with grape seed extract (GSE) through vacuum impregnation (VI) on refrigerated tilapia (Oreochromis niloticus) fillets over 12 days. The VI of FG-GSE significantly improved the quality of the fish by decreasing drip loss, texture changes, and microbial survival. It also delayed protein oxidation by inhibiting the formation of disulphide bonds and carbonyl groups, and maintaining a higher sulfhydryl content and Ca2+-ATPase activity. Regarding myofibril degradation, FG-GSE maintained their secondary structure by increasing the ratio of α-helices and ß-sheets (70.88-75.51%). Atomic force microscopy further revealed that the FG-GSE coating preserved the myofibril nanostructure by maintaining their length, width, and height. Overall, the synergistic effects of VI with 3% FG and 0.9% GSE suggested a promising approach for fillet preservation.


Assuntos
Proteínas de Peixes/química , Gelatina/química , Extrato de Sementes de Uva/química , Animais , ATPases Transportadoras de Cálcio/metabolismo , Proteínas de Peixes/metabolismo , Bactérias Gram-Negativas/efeitos dos fármacos , Extrato de Sementes de Uva/farmacologia , Dureza , Microscopia de Força Atômica , Miofibrilas/metabolismo , Oxirredução , Estrutura Secundária de Proteína , Alimentos Marinhos/análise , Compostos de Sulfidrila/metabolismo , Tilápia/metabolismo , Vácuo
11.
Int J Biol Macromol ; 133: 987-997, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31029624

RESUMO

This study investigates the purification and biochemical characteristics of the protease secreted by Lactobacillus curvatus R5, which was isolated from Harbin dry sausages. The optimized fermentation conditions were fermentation time 36 h, initial pH 6 and fermentation temperature 37 °C. An extracellular protease was purified using ammonium sulfate precipitation, ion-exchange layer and gel filtration. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that molecular weight of the purified protease was 45.3 kDa. Protease produced by L. curvatus R5 reached a higher relative protease activity at pH 6, 40 °C, and the purified protease exhibited pH and thermal stability at pH 6 and 40 °C. The microbial protease activity can be inhibited by ethylene diamine tetraacetic acid disodium salt (EDTA). The Vmax and Km of the protease were 53 mg/min and 15.9 mg/mL, respectively. SDS-PAGE reflects the ability of the protease to hydrolyse myofibrillar protein and sarcoplasmic protein, especially on myosin heavy chain, actin, myosin light chain and phosphorylase. The 3D structure and the Ramachandran plot of L. curvatus R5 protease was obtained by homology modelling. The Ramachandran plot analysis revealed that the purified protease was composed of 366 amino acids, and its residues in favoured, allowed, generously allowed and disallowed regions were 84.6%, 11.3%, 3.2% and 0.9% residues, respectively. Molecular docking showed that the substrate actin bound to the protease active site by hydrogen bonding and hydrophobic interaction. This research provides a basis for understanding the enzymatic properties of L. curvatus R5 protease. In conclusion, L. curvatus R5 can be used as a starter culture or protease-producing strain to inoculate Harbin dry sausages.


Assuntos
Espaço Extracelular/enzimologia , Lactobacillus/citologia , Produtos da Carne/microbiologia , Peptídeo Hidrolases/isolamento & purificação , Peptídeo Hidrolases/metabolismo , Domínio Catalítico , Estabilidade Enzimática , Fermentação , Concentração de Íons de Hidrogênio , Hidrólise , Lactobacillus/isolamento & purificação , Lactobacillus/metabolismo , Simulação de Acoplamento Molecular , Miofibrilas/metabolismo , Peptídeo Hidrolases/química , Temperatura Ambiente
12.
PLoS One ; 14(4): e0214740, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30964911

RESUMO

Pulmonary hypertension (PH) increases the work of the right ventricle (RV) and causes right-sided heart failure. This study examined RV mitochondrial function and ADP transfer in PH animals advancing to right heart failure, and investigated a potential therapy with the specific ß1-adrenergic-blocker metoprolol. Adult Wistar rats (317 ± 4 g) were injected either with monocrotaline (MCT, 60 mg kg-1) to induce PH, or with an equivalent volume of saline for controls (CON). At three weeks post-injection the MCT rats began oral metoprolol (10 mg kg-1 day-1-) or placebo treatment until heart failure was observed in the MCT group. Mitochondrial function was then measured using high-resolution respirometry from permeabilised RV fibres. Relative to controls, MCT animals had impaired mitochondrial function but maintained coupling between myofibrillar ATPases and mitochondria, despite an increase in ADP diffusion distances. Cardiomyocytes from the RV of MCT rats were enlarged, primarily due to an increase in myofibrillar protein. The ratio of mitochondria per myofilament area was decreased in both MCT groups (p ≤ 0.05) in comparison to control (CON: 1.03 ± 0.04; MCT: 0.74 ± 0.04; MCT + BB: 0.74 ± 0.03). This not only implicates impaired energy production in PH, but also increases the diffusion distance for metabolites within the MCT cardiomyocytes, adding an additional hindrance to energy supply. Together, these changes may limit energy supply in MCT rat hearts, particularly at high cardiac workloads. Metoprolol treatment did not delay the onset of heart failure symptoms, improve mitochondrial function, or regress RV hypertrophy.


Assuntos
Antagonistas de Receptores Adrenérgicos beta 1/farmacologia , Metoprolol/farmacologia , Mitocôndrias/efeitos dos fármacos , Função Ventricular Direita/efeitos dos fármacos , Adenosina Trifosfatases/metabolismo , Administração Oral , Antagonistas de Receptores Adrenérgicos beta 1/uso terapêutico , Animais , Modelos Animais de Doenças , Metabolismo Energético/efeitos dos fármacos , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/prevenção & controle , Hipertensão Pulmonar/induzido quimicamente , Hipertensão Pulmonar/tratamento farmacológico , Masculino , Metoprolol/uso terapêutico , Mitocôndrias/metabolismo , Monocrotalina/toxicidade , Miócitos Cardíacos/citologia , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Miofibrilas/metabolismo , Miofibrilas/patologia , Fosforilação Oxidativa/efeitos dos fármacos , Efeito Placebo , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo
13.
Med Sci Sports Exerc ; 51(9): 1828-1837, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-30933004

RESUMO

Cancer cachexia, an unintentional body weight loss due to cancer, affects patients' survival, quality of life, and response to chemotherapy. Although exercise training is a promising intervention to prevent and treat cancer cachexia, our mechanistic understanding of cachexia's effect on contraction-induced muscle adaptation has been limited to the examination of male mice. Because sex can affect muscle regeneration and response to contraction in humans and mice, the effect of cachexia on the female response to eccentric contraction warrants further investigation. PURPOSE: The purpose of this study was to determine whether high-frequency electric stimulation (HFES) could attenuate muscle mass loss during the progression of cancer cachexia in female tumor-bearing mice. METHODS: Female wild-type (WT) and Apc (Min) mice (16-18 wk old) performed either repeated bouts or a single bout of HFES (10 sets of 6 repetitions, ~22 min), which eccentrically contracts the tibialis anterior (TA) muscle. TA myofiber size, oxidative capacity, anabolic signaling, and catabolic signaling were examined. RESULTS: Min had reduced TA muscle mass and type IIa and type IIb fiber sizes compared with WT. HFES increased the muscle weight and the mean cross-sectional area of type IIa and type IIb fibers in WT and Min mice. HFES increased mTOR signaling and myofibrillar protein synthesis and attenuated cachexia-induced AMPK activity. HFES attenuated the cachexia-associated decrease in skeletal muscle oxidative capacity. CONCLUSION: HFES in female mice can activate muscle protein synthesis through mTOR signaling and repeated bouts of contraction can attenuate cancer-induced muscle mass loss.


Assuntos
Caquexia/fisiopatologia , Caquexia/terapia , Terapia por Estimulação Elétrica/métodos , Músculo Esquelético/fisiopatologia , Animais , Peso Corporal , Caquexia/etiologia , Creatina Quinase/sangue , Modelos Animais de Doenças , Feminino , Humanos , Camundongos , Contração Muscular/fisiologia , Proteínas Musculares/biossíntese , Músculo Esquelético/patologia , Miofibrilas/metabolismo , Miofibrilas/patologia , Neoplasias/complicações , Tamanho do Órgão , Transdução de Sinais/fisiologia , Serina-Treonina Quinases TOR/fisiologia
14.
J Biol Chem ; 294(16): 6364-6374, 2019 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-30819805

RESUMO

The formation of new myofibers in vertebrates occurs by myoblast fusion and requires fusogenic activity of the muscle-specific membrane protein myomaker. Here, using in silico (BLAST) genome analyses, we show that the myomaker gene from trout includes 14 minisatellites, indicating that it has an unusual structure compared with those of other animal species. We found that the trout myomaker gene encodes a 434-amino acid (aa) protein, in accordance with its apparent molecular mass (∼40 kDa) observed by immunoblotting. The first half of the trout myomaker protein (1-220 aa) is similar to the 221-aa mouse myomaker protein, whereas the second half (222-234 aa) does not correspond to any known motifs and arises from two protein extensions. The first extension (∼70 aa) apparently appeared with the radiation of the bony fish clade Euteleostei, whereas the second extension (up to 236 aa) is restricted to the superorder Protacanthopterygii (containing salmonids and pike) and corresponds to the insertion of minisatellites having a length of 30 nucleotides. According to gene expression analyses, trout myomaker expression is consistently associated with the formation of new myofibers during embryonic development, postlarval growth, and muscle regeneration. Using cell-mixing experiments, we observed that trout myomaker has retained the ability to drive the fusion of mouse fibroblasts with C2C12 myoblasts. Our work reveals that trout myomaker has fusogenic function despite containing two protein extensions.


Assuntos
Proteínas de Peixes , Regulação da Expressão Gênica/fisiologia , Proteínas de Membrana , Repetições Minissatélites , Proteínas Musculares , Oncorhynchus mykiss , Animais , Proteínas de Peixes/genética , Proteínas de Peixes/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Miofibrilas/metabolismo , Oncorhynchus mykiss/genética , Oncorhynchus mykiss/metabolismo
15.
Food Chem ; 287: 93-99, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-30857723

RESUMO

The influence of pH-induced structural modifications of myofibrillar proteins (MPs) on their interaction mechanisms with pyrazine compounds was investigated. At a lower pH (4.9, 5.5), MPs aggregated to larger particle sizes due to enhanced the protein-protein interactions. The binding with pyrazine compounds was strongly affected by pH and the nature of flavor compounds. MPs exhibited flavor releasing behavior, probably due to protein-protein interactions and surface tension. Fluorescence analysis revealed that the interaction of pyrazine compounds with MPs followed a combination of static and dynamic quenching. The changes in quenching constant (Ksv) might be attributed to a dynamic quenching, probably due to protein aggregation. The percentages of free 2,5-Dimethylpyrazine (2,5-DMP) were similar to Ksv. Thermodynamic parameters indicated that electrostatic interactions and hydrophobic interactions were the major acting forces in the binding of MPs to 2,5-DMP. The binding of 2,5-DMP increased the α-helix content of MPs.


Assuntos
Proteínas Musculares , Miofibrilas , Pirazinas , Animais , Concentração de Íons de Hidrogênio , Proteínas Musculares/química , Proteínas Musculares/metabolismo , Miofibrilas/química , Miofibrilas/metabolismo , Pirazinas/química , Pirazinas/metabolismo , Suínos
16.
Circ Res ; 124(8): 1228-1239, 2019 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-30732532

RESUMO

RATIONALE: Subcellular Ca2+ indicators have yet to be developed for the myofilament where disease mutation or small molecules may alter contractility through myofilament Ca2+ sensitivity. Here, we develop and characterize genetically encoded Ca2+ indicators restricted to the myofilament to directly visualize Ca2+ changes in the sarcomere. OBJECTIVE: To produce and validate myofilament-restricted Ca2+ imaging probes in an adenoviral transduction adult cardiomyocyte model using drugs that alter myofilament function (MYK-461, omecamtiv mecarbil, and levosimendan) or following cotransduction of 2 established hypertrophic cardiomyopathy disease-causing mutants (cTnT [Troponin T] R92Q and cTnI [Troponin I] R145G) that alter myofilament Ca2+ handling. METHODS AND RESULTS: When expressed in adult ventricular cardiomyocytes RGECO-TnT (Troponin T)/TnI (Troponin I) sensors localize correctly to the sarcomere without contractile impairment. Both sensors report cyclical changes in fluorescence in paced cardiomyocytes with reduced Ca2+ on and increased Ca2+ off rates compared with unconjugated RGECO. RGECO-TnT/TnI revealed changes to localized Ca2+ handling conferred by MYK-461 and levosimendan, including an increase in Ca2+ binding rates with both levosimendan and MYK-461 not detected by an unrestricted protein sensor. Coadenoviral transduction of RGECO-TnT/TnI with hypertrophic cardiomyopathy causing thin filament mutants showed that the mutations increase myofilament [Ca2+] in systole, lengthen time to peak systolic [Ca2+], and delay [Ca2+] release. This contrasts with the effect of the same mutations on cytoplasmic Ca2+, when measured using unrestricted RGECO where changes to peak systolic Ca2+ are inconsistent between the 2 mutations. These data contrast with previous findings using chemical dyes that show no alteration of [Ca2+] transient amplitude or time to peak Ca2+. CONCLUSIONS: RGECO-TnT/TnI are functionally equivalent. They visualize Ca2+ within the myofilament and reveal unrecognized aspects of small molecule and disease-associated mutations in living cells.


Assuntos
Cálcio/metabolismo , Cardiomiopatia Hipertrófica/genética , Mutação , Miócitos Cardíacos/metabolismo , Miofibrilas/metabolismo , Sarcômeros/metabolismo , Adenosina Trifosfatases/antagonistas & inibidores , Adenosina Trifosfatases/metabolismo , Adenoviridae , Animais , Benzilaminas/farmacologia , Cardiomiopatia Hipertrófica/metabolismo , Cobaias , Técnicas In Vitro , Masculino , Miofibrilas/efeitos dos fármacos , Miosinas/efeitos dos fármacos , Miosinas/metabolismo , Simendana/farmacologia , Transdução Genética/métodos , Troponina I/genética , Troponina I/metabolismo , Troponina T/genética , Troponina T/metabolismo , Uracila/análogos & derivados , Uracila/farmacologia , Ureia/análogos & derivados , Ureia/farmacologia
17.
J Nutr ; 149(2): 221-230, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30722014

RESUMO

BACKGROUND: Age-related decline in skeletal muscle mass is at least partly attributed to anabolic resistance to food intake. Resistance exercise sensitizes skeletal muscle tissue to the anabolic properties of amino acids. OBJECTIVE: The present study assessed protein digestion and amino acid absorption kinetics, whole-body protein balance, and the myofibrillar protein synthetic response to ingestion of different amounts of protein during recovery from resistance exercise in older men. METHODS: Forty-eight healthy older men [mean ± SEM age: 66 ± 1 y; body mass index (kg/m2): 25.4 ± 0.3] were randomly assigned to ingest 0, 15, 30, or 45 g milk protein concentrate after a single bout of resistance exercise consisting of 4 sets of 10 repetitions of leg press and leg extension and 2 sets of 10 repetitions of lateral pulldown and chest press performed at 75-80% 1-repetition maximum. Postprandial protein digestion and amino acid absorption kinetics, whole-body protein metabolism, and myofibrillar protein synthesis rates were assessed using primed, continuous infusions of l-[ring-2H5]-phenylalanine, l-[ring-2H2]-tyrosine, and l-[1-13C]-leucine combined with ingestion of intrinsically l-[1-13C]-phenylalanine and l-[1-13C]-leucine labeled protein. RESULTS: Whole-body net protein balance showed a dose-dependent increase after ingestion of 0, 15, 30, or 45 g of protein (0.015 ± 0.002, 0.108 ± 0.004, 0.162 ± 0.008, and 0.215 ± 0.009 µmol Phe · kg-1 · min-1, respectively; P < 0.001). Myofibrillar protein synthesis rates were higher after ingesting 30 (0.0951% ± 0.0062%/h, P = 0.07) or 45 g of protein (0.0970% ± 0.0062%/h, P < 0.05) than after 0 g (0.0746% ± 0.0051%/h). Incorporation of dietary protein-derived amino acids (l-[1-13C]-phenylalanine) into de novo myofibrillar protein showed a dose-dependent increase after ingestion of 15, 30, or 45 g protein (0.0171 ± 0.0017, 0.0296 ± 0.0030, and 0.0397 ± 0.0026 mole percentage excess, respectively; P < 0.05). CONCLUSIONS: Dietary protein ingested during recovery from resistance exercise is rapidly digested and absorbed. Whole-body net protein balance and dietary protein-derived amino acid incorporation into myofibrillar protein show dose-dependent increases. Ingestion of ≥30 g protein increases postexercise myofibrillar protein synthesis rates in older men. This trial was registered at Nederlands Trial Register as NTR4492.


Assuntos
Aminoácidos/metabolismo , Proteínas na Dieta/administração & dosagem , Proteínas Musculares/metabolismo , Miofibrilas/metabolismo , Treinamento de Resistência , Idoso , Idoso de 80 Anos ou mais , Aminoácidos/sangue , Aminoácidos/química , Digestão , Relação Dose-Resposta a Droga , Método Duplo-Cego , Humanos , Masculino , Pessoa de Meia-Idade , Proteínas Musculares/química , Período Pós-Prandial
18.
Food Chem ; 275: 105-112, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30724176

RESUMO

The aim of this study was to determine the effect of postmortem ageing on quality attributes of frozen/thawed lamb loins. The loins (M. Longissimus dorsi; n = 30) were randomly divided into six groups: five frozen treatment groups and the control (4 °C for 120 h). Treatment groups were frozen for 3 weeks and thawed at 4 °C overnight, muscles were preserved at 4 °C until 120 h. Compared to the control, pH values and color of frozen meat declined (P < 0.05) after ageing for 72 h, lower shear force values and higher water loss with earlier freezing were due to extensive degradation of myofibril protein. These results indicated the loins frozen in earlier period could accelerate ageing rate, but impaired meat quality inevitably, freezing between 12 h and 24 h postmortem was a better consideration.


Assuntos
Conservação de Alimentos/métodos , Músculos Paraespinais/química , Mudanças Depois da Morte , Carne Vermelha , Animais , Cor , Qualidade dos Alimentos , Congelamento , Concentração de Íons de Hidrogênio , Miofibrilas/metabolismo , Músculos Paraespinais/metabolismo , Carne Vermelha/análise , Carneiro Doméstico , Água/química
19.
Food Chem ; 275: 77-84, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30724261

RESUMO

The aim of this study was to investigate the dual effect of the nitric oxide donor NOR-3 and calpastatin on µ-calpain activity, autolysis, and proteolytic ability. µ-Calpain and calpastatin were purified and allocated to the following five treatments: µ-calpain, µ-calpain + calpastatin, µ-calpain + NOR-3, µ-calpain + calpastatin + NOR-3, and µ-calpain + NOR-3 + calpastatin. µ-Calpain autolysis and the activity against purified myofibrils was initiated by addition of calcium. Results showed that NOR-3 could induce µ-calpain S-nitrosylation and effectively block the activity via the inhibition of µ-calpain autolysis. Calpastatin inhibited µ-calpain activity in a dose-dependent manner. The combined treatment of NOR-3 and calpastatin exerted a further inhibitory effect on µ-calpain activity, autolysis and proteolysis which was affected by the addition order of NOR-3 and calpastatin. Our data suggest that S-nitrosylation may play a regulatory role in mediating µ-calpain activity in the presence of calpastatin.


Assuntos
Proteínas de Ligação ao Cálcio/metabolismo , Calpaína/antagonistas & inibidores , Óxido Nítrico/metabolismo , Animais , Autólise/metabolismo , Proteínas de Ligação ao Cálcio/farmacologia , Calpaína/metabolismo , Inibidores de Cisteína Proteinase/metabolismo , Inibidores de Cisteína Proteinase/farmacologia , Relação Dose-Resposta a Droga , Miofibrilas/metabolismo , Óxido Nítrico/farmacologia , Nitrocompostos/farmacologia , Proteólise , Suínos
20.
Arch Biochem Biophys ; 664: 62-67, 2019 03 30.
Artigo em Inglês | MEDLINE | ID: mdl-30710504

RESUMO

Movement of the myocardium can modify organ-level cardiac function and its molecular (crossbridge) mechanisms. This motion, which is defined by myocardial strain and strain rate (muscle shortening, lengthening, and the speed of these movements), occurs throughout the cardiac cycle, including during isovolumic periods. This review highlights how the left ventricular myocardium moves throughout the cardiac cycle, how muscle mechanics experiments provide insight into the regulation of forces used to move blood in and out of the left ventricle, and its impact on (and regulation by) crossbridge and sarcomere kinetics. We specifically highlight how muscle mechanics experiments explain how myocardial relaxation is accelerated by lengthening (strain rate) during late systole and isovolumic relaxation, a lengthening which has been measured in human hearts. Advancing and refining both in vivo measurement and ex vivo protocols with physiologic strain and strain rates could reveal important insights into molecular (crossbridge) kinetics. These advances could provide an improvement in both diagnosis and precise treatment of cardiac dysfunction.


Assuntos
Coração/fisiologia , Miofibrilas/metabolismo , Estresse Mecânico , Animais , Humanos , Movimento
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA