-
International Journal of Molecular... Oct 2022Computational modeling can provide a mechanistic and quantitative framework for describing intracellular spatial heterogeneity of solutes such as oxygen partial pressure...
Computational modeling can provide a mechanistic and quantitative framework for describing intracellular spatial heterogeneity of solutes such as oxygen partial pressure (pO). This study develops and evaluates a finite-element model of oxygen-consuming mitochondrial bioenergetics using the COMSOL Multiphysics program. The model derives steady-state oxygen (O) distributions from Fickian diffusion and Michaelis-Menten consumption kinetics in the mitochondria and cytoplasm. Intrinsic model parameters such as diffusivity and maximum consumption rate were estimated from previously published values for isolated and intact mitochondria. The model was compared with experimental data collected for the intracellular and mitochondrial pO levels in human cervical cancer cells (HeLa) in different respiratory states and under different levels of imposed pO. Experimental pO gradients were measured using lifetime imaging of a Förster resonance energy transfer (FRET)-based O sensor, Myoglobin-mCherry, which offers in situ real-time and noninvasive measurements of subcellular pO in living cells. On the basis of these results, the model qualitatively predicted (1) the integrated experimental data from mitochondria under diverse experimental conditions, and (2) the impact of changes in one or more mitochondrial processes on overall bioenergetics.
Topics: Humans; Oxygen; Oxygen Consumption; Myoglobin; Computer Simulation; Energy Metabolism
PubMed: 36293452
DOI: 10.3390/ijms232012597 -
Chembiochem : a European Journal of... Sep 2022Myoglobin (Mb) can react with hydrogen peroxide (H O ) to form a highly active intermediate compound and catalyse oxidation reactions. To enhance this activity, known as...
Myoglobin (Mb) can react with hydrogen peroxide (H O ) to form a highly active intermediate compound and catalyse oxidation reactions. To enhance this activity, known as pseudo-peroxidase activity, previous studies have focused on the modification of key amino acid residues of Mb or the heme cofactor. In this work, the Mb scaffold (apo-Mb) was systematically reconstituted with a set of cofactors based on six metal ions and two ligands. These Mb variants were fully characterised by UV-Vis spectroscopy, circular dichroism (CD) spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS) and native mass spectrometry (nMS). The steady-state kinetics of guaiacol oxidation and 2,4,6-trichlorophenol (TCP) dehalogenation catalysed by Mb variants were determined. Mb variants with iron chlorin e6 (Fe-Ce6) and manganese chlorin e6 (Mn-Ce6) cofactors were found to have improved catalytic efficiency for both guaiacol and TCP substrates in comparison with wild-type Mb, i. e. Fe-protoporphyrin IX-Mb. Furthermore, the selected cofactors were incorporated into the scaffold of a Mb mutant, swMb H64D. Enhanced peroxidase activity for both substrates were found via the reconstitution of Fe-Ce6 into the mutant scaffold.
Topics: Amino Acids; Guaiacol; Heme; Hydrogen Peroxide; Manganese; Myoglobin; Peroxidases
PubMed: 35816250
DOI: 10.1002/cbic.202200197 -
Proteins Nov 2018Myoglobin and hemoglobin are globular hemeproteins, when the former is a monomer and the latter a heterotetramer. Despite the structural similarity of myoglobin to α... (Comparative Study)
Comparative Study
Myoglobin and hemoglobin are globular hemeproteins, when the former is a monomer and the latter a heterotetramer. Despite the structural similarity of myoglobin to α and β subunits of hemoglobin, there is a functional difference between the two proteins, owing to the quaternary structure of hemoglobin. The effect of the quaternary structure of hemoglobin on the intrinsic dynamics of its subunits is explored by dynamical comparison of the two proteins. Anisotropic Network Model modes of motion were calculated for hemoglobin and myoglobin. Dynamical comparison between the proteins was performed using global and local Anisotropic Network Model mode alignment algorithms based on the algorithms of Smith-Waterman and Needleman-Wunsch for sequence comparison. The results indicate that the quaternary structure of hemoglobin substantially alters the intrinsic dynamics of its subunits, an effect that may contribute to the functional difference between the two proteins. Local dynamics similarity between the proteins is still observed at the major exit route of the ligand.
Topics: Algorithms; Animals; Hemoglobins; Humans; Ligands; Molecular Dynamics Simulation; Myoglobin; Protein Conformation; Protein Multimerization; Protein Subunits; Swine
PubMed: 30183107
DOI: 10.1002/prot.25598 -
Comprehensive Reviews in Food Science... Jan 2022Fish is rich in proteins and lipids, especially those containing polyunsaturated fatty acids, which made them vulnerable to chemical or microbial changes associated with... (Review)
Review
Fish is rich in proteins and lipids, especially those containing polyunsaturated fatty acids, which made them vulnerable to chemical or microbial changes associated with quality loss. Meat color is one of vital criteria indicating the freshness, quality, and acceptability of the meat. Color of meat is governed by the presence of various pigments such as hemoglobin, myoglobin (Mb), and so on. Mb, particularly oxy-form, is responsible for the bright red color of fish muscle, especially tuna, and dark fleshed fish, while astaxanthin (AXT) directly determines the color of salmonids muscle. Microbial spoilage and chemical changes such as oxidation of lipid/proteins result in the autoxidation of Mb or fading of AXT, leading to undesirable color with lower acceptability. The discoloration has been affected by chemical composition, post-harvesting handling or storage, processing, cooking, and so on . To tackle discoloration of fish meat, vacuum or modified atmospheric packaging, low- or ultralow-temperature storage, uses of artificial and natural additives have been employed. This review article provides information regarding the factors affecting color and other quality aspects of fish muscle. Moreover, promising methodologies used to control discoloration are also focused.
Topics: Animals; Color; Meat; Muscles; Myoglobin; Seafood
PubMed: 34859577
DOI: 10.1111/1541-4337.12866 -
Molecular Biology and Evolution Dec 2016Myoglobin is a respiratory protein that serves as a model system in a variety of biological fields. Its main function is to deliver and store O in the heart and skeletal...
Myoglobin is a respiratory protein that serves as a model system in a variety of biological fields. Its main function is to deliver and store O in the heart and skeletal muscles, but myoglobin is also instrumental in homeostasis of nitric oxide (NO) and detoxification of reactive oxygen species (ROS). Almost every vertebrate harbors a single myoglobin gene; only some cyprinid fishes have two recently duplicated myoglobin genes. Here we show that the West African lungfish Protopterus annectens has at least seven distinct myoglobin genes (PanMb1-7), which diverged early in the evolution of lungfish and showed an enhanced evolutionary rate. These myoglobins are lungfish specific, and no other globin gene was found amplified. The myoglobins are differentially expressed in various lungfish tissues, and the brain is the main site of myoglobin expression. The typical myoglobin-containing tissues, the skeletal muscle and the heart, have much lower myoglobin mRNA levels. Muscle and heart express distinct myoglobins (PanMb1 and PanMb3, respectively). In cell culture, lungfish myoglobins improved cellular survival under hypoxia albeit with different efficiencies and reduced the production of reactive oxygen species. Only Mb2 and Mb6 enhanced the energy status of the cells. The unexpected diversity of myoglobin hints to a functional diversification of this gene: some myoglobins may have adapted to the O requirements of the specific tissue and help the lungfish to survive hypoxic periods; other myoglobins may have taken over the roles of neuroglobin and cytoglobin, which appear to be missing in the West African lungfish.
Topics: Amino Acid Sequence; Animals; Biological Evolution; Fishes; Gene Duplication; Genetic Variation; Muscle, Skeletal; Myoglobin; Oxygen; Phylogeny; RNA, Messenger; Vertebrates
PubMed: 27512111
DOI: 10.1093/molbev/msw159 -
Biomolecules Oct 2019Recent electronic transport experiments using metallic contacts attached to proteins identified some "stylized facts", which contradict conventional wisdom that...
Recent electronic transport experiments using metallic contacts attached to proteins identified some "stylized facts", which contradict conventional wisdom that increasing either the spatial distance between the electrodes or the temperature suppresses conductance exponentially. These include nearly temperature-independent conductance over the protein in the 30 to 300 K range, distance-independent conductance within a single protein in the 1 to 10 nm range and an anomalously large conductance in the 0.1 to 10 nS range. In this paper, we develop a generalization of the low temperature Landauer formula, which can account for the joint effects of tunneling and decoherence and can explain these new experimental findings. We use novel approximations, which greatly simplify the mathematical treatment and allow us to calculate the conductance in terms of a handful macroscopic parameters, instead of the myriads of microscopic parameters describing the details of an atomic level quantum chemical computation. The new approach makes it possible to get predictions for the outcomes of new experiments without relying solely on high performance computing and can distinguish important and unimportant details of the protein structures from the point of view of transport properties.
Topics: Cytochromes c; Electron Transport; Electrons; Myoglobin; Streptavidin
PubMed: 31614584
DOI: 10.3390/biom9100599 -
Chemistry, An Asian Journal Apr 2016A supramolecular conjugate of myoglobin (Mb) and water-soluble poly(acrylate), (PA5k and PA25k , where 5k and 25k represent the molecular weight of the polymers,...
A supramolecular conjugate of myoglobin (Mb) and water-soluble poly(acrylate), (PA5k and PA25k , where 5k and 25k represent the molecular weight of the polymers, respectively), is constructed on the basis of a noncovalent heme-heme pocket interaction. The modified heme with an amino group linked to the terminus of one of the heme-propionates is coupled to the side-chain carboxyl groups of poly(acrylate) activated by N-hydroxysuccinimide. The ratios of the heme-modified monomer unit and the unmodified monomer unit (m:n) in the polymer chains of Heme-PA5k and Heme-PA25k were determined to be 4.5:95.5 and 3.1:96.9, respectively. Subsequent addition of apoMb to the conjugated polymers provides Mb-connected fibrous nanostructures confirmed by atomic force microscopy. A mixture of the heme-modified polymer and dimeric apomyoglobin as a cross-linker forms a microgel in which the reconstituted myoglobin retains its native exogenous ligand binding activity.
Topics: Acrylates; Carrier Proteins; Gels; Molecular Structure; Myoglobin; Oxygen; Polymers
PubMed: 26890010
DOI: 10.1002/asia.201501415 -
Frontiers in Endocrinology 2021Myoglobin (MB) is an oxygen-binding protein usually found in cardiac myocytes and skeletal muscle fibers. It may function as a temporary storage and transport protein...
Myoglobin (MB) is an oxygen-binding protein usually found in cardiac myocytes and skeletal muscle fibers. It may function as a temporary storage and transport protein for O but could also have scavenging capacity for reactive oxygen and nitrogen species. In addition, MB has recently been identified as a hallmark in luminal breast cancer and was shown to be robustly induced under hypoxia. Cellular responses to hypoxia are regulated by the transcription factor hypoxia-inducible factor (HIF). For exploring the function of MB in breast cancer, we employed the human cell line MDA-MB-468. Cells were grown in monolayer or as 3D multicellular spheroids, which mimic the avascular tumor architecture and physiology with a heterogeneous cell population of proliferating cells in the rim and non-cycling or necrotic cells in the core region. This central necrosis was increased after MB knockdown, indicating a role for MB in hypoxic tumor regions. In addition, MB knockdown caused higher levels of HIF-1α protein after treatment with NO, which also plays an important role in cancer cell survival. MB knockdown also led to higher reactive oxygen species (ROS) levels in the cells after treatment with HO. To further explore the role of MB in cell survival, we performed RNA-Seq after MB knockdown and NO treatment. 1029 differentially expressed genes (DEGs), including 45 potential HIF-1 target genes, were annotated in regulatory pathways that modulate cellular function and maintenance, cell death and survival, and carbohydrate metabolism. Of these target genes, , , , , and were significantly altered. Consistently, a decreased expression of , , and after MB knockdown was confirmed by qPCR. All three genes of interest are often up regulated in cancer and correlate with a poor clinical outcome. Thus, our data indicate that myoglobin might influence the survival of breast cancer cells, possibly due to its ROS and NO scavenging properties and could be a valuable target for cancer therapy.
Topics: Breast Neoplasms; Cell Survival; Female; Free Radical Scavengers; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Humans; Myoglobin; Nitric Oxide; Protective Agents; RNA, Small Interfering; Reactive Oxygen Species; Signal Transduction; Tumor Cells, Cultured
PubMed: 34671319
DOI: 10.3389/fendo.2021.732190 -
Small (Weinheim An Der Bergstrasse,... Nov 2017Highly reliable detection, imaging, and monitoring of reactive oxygen species (ROS) are critical for understanding and studying the biological roles and pathogenesis of...
Highly reliable detection, imaging, and monitoring of reactive oxygen species (ROS) are critical for understanding and studying the biological roles and pathogenesis of ROS. This study describes the design and synthesis of myoglobin and polydopamine-engineered surface-enhanced Raman scattering (MP-SERS) nanoprobes with strong, tunable SERS signals that allow for specifically detecting and imaging ROS sensitively and quantitatively. The study shows that a polydopamine nanolayer can facilitate the modification of Raman-active myoglobins and satellite Au nanoparticles (s-AuNPs) to a plasmonic core AuNP (c-AuNP) in a controllable manner and the generation of plasmonically coupled hot spots between a c-AuNP and s-AuNPs that can induce strong SERS signals. The six-coordinated Fe(III)-OH of myoglobins in plasmonic hotspots is reacted with ROS (H O , •OH, and O ) to form Fe(IV)O. The characteristic Raman peaks of Fe(IV)O from the Fe-porphyrin is used to analyze and quantify ROS. This chemistry allows for these probes to detect ROS in solution and image ROS in cells in a highly designable, specific, and sensitive manner. This work shows that these MP-SERS probes allow for detecting and imaging ROS to differentiate cancerous cells from noncancerous cells. Importantly, for the first time, SERS-based monitoring of the autophagy process in living cells under starvation conditions is validated.
Topics: Autophagy; Cell Survival; Gold; HeLa Cells; Humans; Indoles; Lysosomes; Metal Nanoparticles; Myoglobin; Polymers; Reactive Oxygen Species; Spectrum Analysis, Raman
PubMed: 28902980
DOI: 10.1002/smll.201701584 -
Spectrochimica Acta. Part A, Molecular... May 2019Protein aggregation leads to vast conformational changes and plays a key role in the pathogenesis of various neurodegenerative diseases including Alzheimer's and...
Protein aggregation leads to vast conformational changes and plays a key role in the pathogenesis of various neurodegenerative diseases including Alzheimer's and Parkinson's. In the current piece of work, we have explored the interaction of quinoline yellow (QY) with myoglobin (Mb) at two different pH (3.5 and 7.4). Various spectroscopic techniques such as turbidity, Rayleigh light scattering (RLS), UV-Vis absorbance, fluorescence resonance energy transfer (FRET), far UV-CD along with transmission electron microscopy (TEM) and molecular docking have been utilized to characterize dye-induced aggregation in Mb. Binding results showed that interaction between QY and myoglobin is spontaneous and static in nature with high K value of 2.14 × 10 M. On the other hand, thermodynamics studies (∆H & ∆S) revealed that complex formation was driven by hydrogen and Van der Walls forces. Molecular docking analysis showed strong binding affinity (K = 4.95 × 10 M) between QY and Mb at Pro100, Ile101, Lys102, Glu105, Glu136, Arg139, Lys140, and Ala143 residues. The intrinsic fluorescence and circular dichroism studies indicated that QY induced conformational changes in Mb at pH 3.5. Turbidity and RLS studies showed aggregation of Mb in the presence of QY (0.2-5 mM). Moreover, kinetics data revealed nucleation independent aggregation of myoglobin in the presence of QY. TEM analysis further established amorphous nature of Mb aggregate induced by QY. At pH (7.4), QY was unable to induce aggregation in myoglobin; it might be due to repulsive nature of negatively charged dye and myoglobin or partially altered states of protein could be pre-requisite for binding and aggregation.
Topics: Animals; Circular Dichroism; Fluorescence Resonance Energy Transfer; Food Coloring Agents; Horses; Hydrogen-Ion Concentration; Molecular Docking Simulation; Myoglobin; Protein Aggregates; Protein Binding; Quinolines; Spectrometry, Fluorescence
PubMed: 30785041
DOI: 10.1016/j.saa.2019.01.090