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Journal of Biomedical Optics May 2016We propose a simple, rapid, and nondestructive method to investigate formation, accumulation, and degradation of met-myoglobin (met-Mb) and myoglobin oxygenation from...
We propose a simple, rapid, and nondestructive method to investigate formation, accumulation, and degradation of met-myoglobin (met-Mb) and myoglobin oxygenation from the interior of porcine meat. For the experiment, color photos and attenuance spectra of porcine meat (well-bled muscle, fat, and mixed) were collected daily to perform colorimetric analysis and to obtain the differences of attenuance between 578 and 567 nm (A578-A567) and between 615 and 630 nm (A630-A615), respectively. Oxy-, deoxy-, and met-myoglobin concentration changes over storage time were also calculated using Beer–Lamberts’ law with reflectance intensities at 557, 582, and 630 nm. The change of A578-A567 was well matched with the change of myoglobin oxygenation, and the change of A630-A615 corresponded well with the formation and degradation of met-Mb. In addition, attenuation differences, A578-A567 and A630-A615, were able to show the formation of met-Mb earlier than colorimetric analysis. Therefore, the attenuance differences between wavelengths can be indicators for estimating myoglobin oxygenation and met-Mb formation, accumulation, and degradation, which enable us to design a simple device to monitor myoglobin activities in porcine meat.
Topics: Animals; Food Analysis; Meat; Muscles; Myoglobin; Oxygen; Swine
PubMed: 27153774
DOI: 10.1117/1.JBO.21.5.057002 -
Food Chemistry Nov 2021Myoglobin is a protein not easily broken down by digestive enzymes due to its rigid structure. This study evaluated the structural characteristics of myoglobin under...
Myoglobin is a protein not easily broken down by digestive enzymes due to its rigid structure. This study evaluated the structural characteristics of myoglobin under various sodium chloride treatments (0.4-0.8 mol/L for 5-10 h) and the impacts on its digestibility using spectroscopic and molecular dynamics simulation techniques. Myoglobin digestibility was 40% following pepsin digestion and 60% after being sequentially digested by pepsin and trypsin. The α-helix content of myoglobin did not change significantly following sodium chloride treatment but hydrophobic amino acids were exposed and the binding of phenylalanine targeted by some digestive enzymes became more stable, leading to the reduced digestibility.
Topics: Amino Acids; Myoglobin; Pepsin A; Sodium Chloride
PubMed: 34120050
DOI: 10.1016/j.foodchem.2021.130284 -
Meat Science Jul 2023Myoglobin content is considered as a crucial index to evaluate the quality of frozen pork. In this study, a portable visible and near-infrared (Vis-NIR) spectrometer...
Myoglobin content is considered as a crucial index to evaluate the quality of frozen pork. In this study, a portable visible and near-infrared (Vis-NIR) spectrometer combined with chemometrics was used to detect myoglobin content in frozen pork. Metmyoglobin, deoxymyoglobin, oxymyoglobin, and total myoglobin were assessed spectrophotometrically. The raw Vis-NIR spectra of frozen pork samples were pre-processed using 1 derivatives (FD). Afterward, Synergy Interval Partial Least Square (Si-PLS) coupled Competitive Adaptive Reweighted Sampling algorithm (Si-CARS-PLS) was applied to select characteristic variables. The Si-CARS-PLS models revealed the probability of estimating myoglobin content in frozen pork, with predictive correlation coefficients (R) for metmyoglobin, deoxymyoglobin, oxymyoglobin, and total myoglobin as 0.9095, 0.9004, 0.8578, and 0.9133, respectively. The findings of this study showed that Vis-NIR spectroscopy coupled with Si-CARS-PLS is a promising method and offered a way forward for determining the myoglobin content in frozen pork.
Topics: Animals; Swine; Spectroscopy, Near-Infrared; Myoglobin; Metmyoglobin; Pork Meat; Red Meat; Least-Squares Analysis; Algorithms
PubMed: 37004370
DOI: 10.1016/j.meatsci.2023.109170 -
Meat Science Sep 2023The effects of ultrasound (US) on myoglobin modification, nitrous pigment formation, color, and total and free sulfhydryl content in nitrite-free pork meat batter were...
The effects of ultrasound (US) on myoglobin modification, nitrous pigment formation, color, and total and free sulfhydryl content in nitrite-free pork meat batter were assessed. Five treatments were elaborated: Control (without US); TUS10'12 and TUS20'12 (sonication at 25 kHz, at 12 °C for 10 and 20 min, respectively); TUS10'18 and TUS20'18 (sonication at 25 kHz, at 18 °C for 10 and 20 min, respectively). Sonication for 20 min at 12 °C increased OxyMb and DeoxyMb pigments while reducing MetMb levels. This US condition also yielded higher red color indices and lower yellow color indices. Moreover, TUS20'12 exhibited enhanced nitrous pigment formation and decreased FerrylMb and free sulfhydryl (SH) values, indicating reduced oxidation in OxyMb and DeoxyMb pigments. In conclusion, the findings demonstrate that US can impart a cured color to nitrite-free meat products.
Topics: Animals; Swine; Nitrites; Pork Meat; Red Meat; Myoglobin; Oxidation-Reduction
PubMed: 37263032
DOI: 10.1016/j.meatsci.2023.109231 -
International Journal of Molecular... Aug 2022Myoglobin (Mb), besides its roles as an oxygen (O) carrier/storage protein and nitric oxide NO scavenger/producer, may participate in lipid trafficking and metabolite...
Myoglobin (Mb), besides its roles as an oxygen (O) carrier/storage protein and nitric oxide NO scavenger/producer, may participate in lipid trafficking and metabolite binding. Our recent findings have shown that O is released from oxy-Mb upon interaction with lactate (LAC, anerobic glycolysis end-product). Since pyruvate (PYR) is structurally similar and metabolically related to LAC, we investigated the effects of PYR (aerobic glycolysis end-product) on Mb using isothermal titration calorimetry, circular dichroism, and O-kinetic studies to evaluate PYR affinity toward Mb and to compare the effects of PYR and LAC on O release kinetics of oxy-Mb. Similar to LAC, PYR interacts with both oxy- and deoxy-Mb with a 1:1 stoichiometry. Time-resolved circular dichroism spectra revealed that there are no major conformational changes in the secondary structures of oxy- or deoxy-Mb during interactions with PYR or LAC. However, we found contrasting results with respect to binding affinities and substrate preference, where PYR has higher affinity toward deoxy-Mb when compared with LAC (which prefers oxy-Mb). Furthermore, PYR interaction with oxy-Mb releases a significantly lower amount of O than LAC. Taken together, our findings support the hypothesis that glycolytic end-products play a distinctive role in the Mb-rich tissues by serving as novel regulators of O availability, and/or by impacting other activities related to oxy-/deoxy-Mb toggling in resting vs. exercised or metabolically activated conditions.
Topics: Kinetics; Myoglobin; Oxygen; Pyruvic Acid; Structure-Activity Relationship; Thermodynamics
PubMed: 35955898
DOI: 10.3390/ijms23158766 -
PloS One 2017High performance liquid chromatography (HPLC) coupled with a Fraction Collector was employed to isolate Maillard reaction products (MRPs) formed in model systems...
High performance liquid chromatography (HPLC) coupled with a Fraction Collector was employed to isolate Maillard reaction products (MRPs) formed in model systems comprising of asparagine and monosaccharides in the 60-180°C range. The primary MRP which is detected at 60°C is important for Acrylamide content and color/aroma development in foods and also in the field of food biotechnology for controlling the extent of the Maillard reaction with temperature. The discrete fractions of the reaction products were reacted with Hemoglobin (Hb) and Myoglobin (Mb) at physiological conditions and the reaction adducts were monitored by UV-vis and Attenuated Total Reflection-Fourier transform infrared (FTIR) spectrophotometry. The UV-vis kinetic profiles revealed the formation of a Soret transition characteristic of a low-spin six-coordinated species and the ATR-FTIR spectrum of the Hb-MRP and Mb-MRP fractions showed modifications in the protein Amide I and II vibrations. The UV-vis and the FTIR spectra of the Hb-MRPs indicate that the six-coordinated species is a hemichrome in which the distal E7 Histidine is coordinated to the heme Fe and blocks irreversibly the ligand binding site. Although the Mb-MRPs complex is a six-coordinated species, the 1608 cm-1 FTIR band characteristic of a hemichrome was not observed.
Topics: Chromatography, High Pressure Liquid; Hemoglobins; Kinetics; Maillard Reaction; Myoglobin; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared
PubMed: 29136023
DOI: 10.1371/journal.pone.0188095 -
The Journal of Physical Chemistry. B May 2023A common theme for the effect of electric field on the structure and conformation of proteins is lacking due to a myriad of conflicting reports emerging from different...
A common theme for the effect of electric field on the structure and conformation of proteins is lacking due to a myriad of conflicting reports emerging from different protein systems subjected to different frequencies and strengths of the field (0.8 -10 V cm), which may be pulsed for a few nano- to microseconds or applied continuously up to several hours. It is however necessary to find a common theme because of the increasing use of electric field not only to understand Stark-like electro-optic effects in large molecules but also in food processing technology, and perhaps in the disruption of amyloid bodies in Alzheimer's condition. This study finds an optimized condition of 1.3 V cm DC field, in which the electrophoretic mobility is ∼1.2 mm h, and systematically shows electrophoretic, electrochemical, and unfolding effects at different levels of cytochrome c structure within ∼90 min of turning the field on. Interestingly, the protein undergoes amorphous aggregation concomitant with a high degree of denaturation. In support of this suggestion, data for myoglobin and trypsin are also presented. Effort has been made to separate out the chemical and physical effects of the electric field.
Topics: Myoglobin; Electricity
PubMed: 37165949
DOI: 10.1021/acs.jpcb.3c00540 -
Analytical Chemistry Mar 2020Size-exclusion chromatography employing aqueous mobile phases with volatile salts at neutral pH combined with electrospray-ionization mass spectrometry (SEC-ESI-MS) is a...
Size-exclusion chromatography employing aqueous mobile phases with volatile salts at neutral pH combined with electrospray-ionization mass spectrometry (SEC-ESI-MS) is a useful tool to study proteins in their native state. However, whether the applied eluent conditions actually prevent protein-stationary phase interactions, and/or protein denaturation, often is not assessed. In this study, the effects of volatile mobile phase additives on SEC retention and ESI of proteins were thoroughly investigated. Myoglobin was used as the main model protein, and eluents of varying ionic strength and pH were applied. The degree of interaction between protein and stationary phase was evaluated by calculating the SEC distribution coefficient. Protein-ion charge state distributions obtained during offline and online native ESI-MS were used to monitor alterations in protein structure. Interestingly, most of the supposedly mild eluent compositions induced nonideal SEC behavior and/or protein unfolding. SEC experiments revealed that the nature, ionic strength, and pH of the eluent affected protein retention. Protein-stationary phase interactions were effectively avoided using ammonium acetate at ionic strengths above 0.1 M. Direct-infusion ESI-MS showed that the tested volatile eluent salts seem to follow the Hofmeister series: no denaturation was induced using ammonium acetate (kosmotropic), whereas ammonium formate and bicarbonate (both chaotropic) caused structural changes. Using a mobile phase of 0.2 M ammonium acetate (pH 6.9), several proteins (i.e., myoglobin, carbonic anhydrase, and cytochrome c) could be analyzed by SEC-ESI-MS using different column chemistries without compromising their native state. Overall, with SEC-ESI-MS, the effect of nonspecific interactions between protein and stationary phase on the protein structure can be studied, even revealing gradual structural differences along a peak.
Topics: Animals; Chromatography, Gel; Heart; Horses; Hydrogen-Ion Concentration; Myoglobin; Protein Denaturation; Spectrometry, Mass, Electrospray Ionization
PubMed: 32107919
DOI: 10.1021/acs.analchem.9b04961 -
Nature Communications Dec 2023Hemoproteins have recently emerged as promising biocatalysts for new-to-nature carbene transfer reactions. However, mechanistic understanding of the interplay between...
Hemoproteins have recently emerged as promising biocatalysts for new-to-nature carbene transfer reactions. However, mechanistic understanding of the interplay between productive and unproductive pathways in these processes is limited. Using spectroscopic, structural, and computational methods, we investigate the mechanism of a myoglobin-catalyzed cyclopropanation reaction with diazoketones. These studies shed light on the nature and kinetics of key catalytic steps in this reaction, including the formation of an early heme-bound diazo complex intermediate, the rate-determining nature of carbene formation, and the cyclopropanation mechanism. Our analyses further reveal the existence of a complex mechanistic manifold for this reaction that includes a competing pathway resulting in the formation of an N-bound carbene adduct of the heme cofactor, which was isolated and characterized by X-ray crystallography, UV-Vis, and Mössbauer spectroscopy. This species can regenerate the active biocatalyst, constituting a non-productive, yet non-destructive detour from the main catalytic cycle. These findings offer a valuable framework for both mechanistic analysis and design of hemoprotein-catalyzed carbene transfer reactions.
Topics: Myoglobin; Catalysis; Methane; Heme
PubMed: 38042860
DOI: 10.1038/s41467-023-43559-7 -
Journal of Biophotonics Mar 2022The biological relevance of nitric oxide (NO) and reactive oxygen species (ROS) in signaling, metabolic regulation, and disease treatment has become abundantly clear....
The biological relevance of nitric oxide (NO) and reactive oxygen species (ROS) in signaling, metabolic regulation, and disease treatment has become abundantly clear. The dramatic change in NO/ROS processing that accompanies a changing oxygen landscape calls for new imaging tools that can provide cellular details about both [O ] and the production of reactive species. Myoglobin oxidation to the met state by NO/ROS is a known sensor with absorbance changes in the visible range. We previously employed Förster resonance energy transfer to read out the deoxygenation/oxygenation of myoglobin, creating the subcellular [O ] sensor Myoglobin-mCherry. We now add the fluorescent protein EYFP to this sensor to create a novel probe that senses both met formation, a proxy for ROS/NO exposure, and [O ]. Since both proteins are present in the construct, it can also relieve users from the need to measure fluorescence lifetime, making [O ] sensing available to a wider group of laboratories.
Topics: Fluorescence Resonance Energy Transfer; Metmyoglobin; Myoglobin; Nitric Oxide; Oxidation-Reduction; Oxygen; Reactive Oxygen Species
PubMed: 34689421
DOI: 10.1002/jbio.202100166