Myoglobin is a heme-containing protein found primarily in the muscle tissue of horses, where it functions in oxygen storage and transport. It plays a role in muscle metabolism by facilitating the movement of oxygen from the bloodstream to the mitochondria during periods of increased muscular activity. Myoglobin levels in horses can be indicative of muscle health, with elevated levels often associated with muscle damage or exertional rhabdomyolysis. This page compiles peer-reviewed research studies and scholarly articles that investigate the structure, function, and clinical implications of myoglobin in equine physiology and pathology.
Bronstein A, Marx A.Comparison of myoglobin structures reveals that protein isolated from horse heart consistently adopts an alternate turn conformation in comparison to its homologues. Analysis of hundreds of high-resolution structures discounts crystallization conditions or the surrounding amino acid protein environment as explaining this difference, that is also not captured by the AlphaFold prediction. Rather, a water molecule is identified as stabilizing the conformation in the horse heart structure, which immediately reverts to the whale conformation in molecular dynamics simulations excluding that structur...
Delvescovo B.This article describes the most common causes of urine discoloration. The review includes a description of the most common disorders causing hematuria, highlighting clinical presentation, treatments, and pathophysiology. Causes of hemoglobinuria and myoglobinuria together with their mechanisms of renal injury are also reviewed.
The study investigates the changes in meat organoleptic characteristics and sarcoplasmic proteins of 3 horse muscles during aging. Longissimus lumborum (LL), semimembranosus (SM) and semitendinosus (ST) muscles, were removed from 12 Italian Heavy Draft Horse carcasses and aged for 1, 3, 6, 9 and 14 days. The lowest values of hardness and chewiness were found in LL muscle. During aging, a decrease of hardness was observed in ST muscle reaching the lowest value at 14 days. 2DE revealed a decrease of 15 sarcoplasmic protein spots in all muscles. Muscle-differences were found at 14 days. An inc...
Ioannou A, Lambrou A, Daskalakis V, Pinakoulaki E.The coordination of nitrite in myoglobin (Mb) has been characterized by resonance Raman spectroscopy and the frequencies of the nitrite bound to the heme Fe as well to the 2-vinyl have been computed by density functional theory (DFT) calculations. The DFT Natural Bond Orbital (NBO) analysis and the extensive isotope-labeling in the resonance Raman experiments indicate that NO (O1NO2) is bound to the heme Fe via O1. Based on the vibrational characterization of the reversible transition between low and high spin FeONO/2-nitrovinyl species, we suggest that the key step that triggers the spin-chan...
Kim KH, Oang KY, Kim J, Lee JH, Kim Y, Ihee H.Here we report structural dynamics of equine myoglobin (Mb) in response to the CO photodissociation visualized by picosecond time-resolved X-ray solution scattering. The data clearly reveal new structural dynamics that occur in the timescale of ∼360 picoseconds (ps) and ∼9 nanoseconds (ns), which have not been clearly detected in previous studies.
Mancini RA, Suman SP, Konda MK, Ramanathan R, Joseph P, Beach CM.Research focused on determining the fundamental mechanisms by which lactate influences color stability has not considered a direct effect of lactate on myoglobin. Thus, the objective of this study was to use Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry to examine lactate adduction to myoglobin. Equine oxymyoglobin and equine carboxymyoglobin (0.15mM) were incubated with sodium lactate (200mM) at 4 degrees C, pH 5.6 in 50mM sodium citrate buffer or at 37 degrees C, pH 7.4 in 50mM sodium phosphate buffer, simulating typical meat storage and physiological condition...
Valentín-Rodríguez C, López-Garriga J, Torres-Lugo M.Proteins are biological macromolecules which have a unique spatial conformation. Once this 3D spatial conformation is affected the protein's biological stability and activity can be severely limited. For these reasons, this investigation focuses on the effects of pre-polymeric solution components on the behavior of proteins to be encapsulated by the entrapment technique in anionic, cationic, and neutral hydrogel membranes. Equine skeletal muscle myoglobin (MMb), and equine heart myoglobin (HMb) were employed as model molecules. Three hydrogel morphologies were examined: methacrylic acid-poly(e...
Mancini RA, Ramanathan R.Injection-enhancement of beef with lactate improves color stability; however, the mechanism is unclear. Thus, our objectives were to assess the effects of sodium lactate on equine myoglobin redox stability in vitro. Oxymyoglobin at pH 5.6 (50mM sodium citrate) and pH 7.4 (50mM sodium phosphate) was incubated at 4°C with lactate (0, 5, 10, 100, or 200mM) and myoglobin redox form was determined using absorbance spectra. Metmyoglobin formation at pH 5.6 and 7.4 was significantly (P<0.05) decreased by lactate at concentrations of 100 and 200mM. In general, increasing lactate concentration from...
Miksovská J, Day JH, Larsen RW.Carbon monoxide binding to myoglobin was characterized using the photothermal beam deflection method. The volume and enthalpy changes coupled to CO dissociation were found to be 9.3+/-0.8 mL x mol(-1) and 7.4+/-2.8 kcal x mol(-1), respectively. The corresponding values observed for CO rebinding have the same magnitude but opposite sign: Delta V=-8.6+/-0.9 mL x mol(-1) and Delta H=-5.8+/-2.9 kcal x mol(-1). Ligand rebinding occurs as a single conformational step with a rate constant of 5 x 10(5) M(-1) s(-1) and with activation enthalpy of 7.1+/-0.8 kcal x mol(-1) and activation entropy of -22.4...
Yamada S, Suruga K, Ogawa M, Hama T, Satoh T, Kawachi R, Nishio T, Oku T.The appearance of NO2- reducing activity of cytochrome c (Cyt c) upon heat denaturation was investigated with equine heart Cyt c. Denatured equine heart Cyt c (dCyt c), which was treated at 100 degrees C for 30 min, had NO2- reducing activity in the presence of dithionite and methylviologen in an aqueous solution under anaerobic conditions. In contrast, hemoglobin and myoglobin had no such activity under the same conditions. Using spectroscopic methods, we found that the appearance of this activity in the Cyt c was due to the following intramolecular changes: unfolding of the peptide chain, ex...
Hayashi T, Matsuo T, Hitomi Y, Okawa K, Suzuki A, Shiro Y, Iizuka T, Hisaeda Y, Ogoshi H.Horse heart myoglobin was reconstituted with mesohemin derivatives methylated at the 6- or 7-position to evaluate the role of the heme-6-propionate or heme-7-propionate side chain in the protein. The association and dissociation of the O(2) binding for the deoxymyoglobin with 6-methyl-7-propionate mesoheme are clearly accelerated. Furthermore, the myoglobin with 6-methyl-7-propionate mesoheme shows fast autoxidation from oxymyoglobin to metmyoglobin compared to the myoglobin with 6-propionate-7-methyl heme and the reference protein. These results indicate the 6-propionate plays an important ph...
Gunther MR, Sturgeon BE, Mason RP.The reaction between metmyoglobin (metMb) and hydrogen peroxide has been known since the 1950s to produce globin-centered free radicals. The direct electron spin resonance spectrum of a solution of horse metMb and hydrogen peroxide at room temperature consists of a multilined signal that decays in minutes at room temperature. Comparison of the direct ESR spectra obtained from the system under N(2)- and O(2)-saturated conditions demonstrates the presence of a peroxyl radical, identified by its g-value of 2.014. Computer simulations of the spectra recorded 3 s after the mixture of metMb and H(2)...
Lin J, Merryweather J, Vitello LB, Erman JE.The kinetics of formation and dissociation of the horse metmyoglobin/azide complex has been investigated between pH 3.5 and 11.5. The ionic strength dependence of the reaction has been determined at integral pH values between 5 and 10. Hydrazoic acid, HN3, binds to metmyoglobin with a rate constant of (3.8 +/- 1.0) x 10(5) M-1 s-1. Protonation of a group with an apparent pKa of 4.0 +/- 0.3 increases the rate of HN3 binding 6.5-fold to (2.5 +/- 0.8) x 10(6) M-1 s-1. The ionizable group is attributed to the distal histidine, His-64. The azide anion, N-3, binds to metmyoglobin with a rate constan...
Conley KE, Jones C.We test the hypothesis that myoglobin is important for O2 supply near the oxidative capacity of muscle. This hypothesis is evaluated with a simple model that incorporates the properties of heart and skeletal muscle tissue taken from steers and horses exercising at their maximum O2 consumption rate. These tissue samples allowed us to set the bounds on oxidative demand and O2 flux from red blood cells to the core of the muscle fiber, to estimate the blood and tissue capacities for O2 diffusion, and to define the capillary blood PO2 driving this O2 flux. A model combining blood convection with ti...
Lloyd E, Mauk AG.Expression of recombinant horse heart myoglobin in Escherichia coli has been found to result in the production of both native and variable amounts (approximately 16-17% total) of two sulphmyoglobin isomers. The recombinant sulphmyoglobin produced consists primarily of the A and B isomers as identified by 1H NMR spectroscopy with no evidence for production of the C isomer. Conversion of recombinant sulphmyoglobin to the native protein can be achieved by reconstitution with protohaem IX. The possible relationship of this observation to recombinant expression of other heme proteins is discussed.
Santucci R, Ascoli F, La Mar GN, Pandey RK, Smith KM.The reconstitution kinetics of horse heart myoglobin, as met-cyano derivative, with two synthetic hemins in which the 6- or the 7-propionate is replaced by a methyl group, has been investigated by circular dichroism, in order to gain information on the heme re-orientation process following the heme insertion into the globin pocket. The results obtained confirm that the preferred heme orientation places the sole propionate into the position occupied by the 6-propionate in the crystal structure, supporting the importance of the salt bridge occurring between this propionate and the basic CD3 resi...
Valberg S, Jönsson L, Lindholm A, Holmgren N.Six horses with a history of recurrent exertional rhabdomyolysis (RER) (Horses A-F) and 7 control horses performed a submaximal and later a near-maximal treadmill exercise test. Blood samples were obtained before, during and after exercise and muscle biopsies were taken before and after exercise. At rest, plasma aspartate aminotransferase (AST) activities in horses with RER were above 95% confidence intervals for control horses. During submaximal exercise, 3 horses with RER (A, B and C) had much greater increases in plasma AST, creatine kinase (CK) and myoglobin concentrations than did Horses ...
Holmgren N, Valberg S.Quantitative immunodiffusion in one dimension was performed in 6-mm Duran tubes containing a 1% Nobel agar solution and various dilutions of antisera. A series of dilutions of pure myoglobin in equine sera as well as plasma from horses with rhabdomyolysis were tested. Standard curves were prepared of the migration distance of the formed precipitate from the meniscus of the gel after 3, 6, 12, and 24 hours. The clearest line of precipitate was formed with a 1:20 dilution of antisera in agar. Standard curves were nonlinear and plasma myoglobin could be detected at 2 micrograms of myoglobin/ml or...
Folin M, Gennari G, Jori G.The irradiation of horse and sperm-whale Fe” or Fez’ myoglobins with visible light
showed that axial ligands that render the heme diamagnetic (e.g. 02, CO or CN-) endow the
hemoproteins with a marked photosensitivity. In contrast, high-spin myoglobins are unaffected by
visible light. These findings appear to be of general validity for all hemo-proteins and are in agreement
with the involvment of the triplet state of the heme as the reactive intermediate. In all cases, the overall
photoprocess occurs within a very narrow spatial range, leading to specific modification of these
photoox...
Van den Oord AH, Wesdorp JJ, Van Dam AF, Verheij JA.In commercial samples of equine myoglobin and samples of equine and bovine myoglobin prepared in the laboratory, a small amount of the protein was present as an aggregate. The presence of the myoglobin aggregate could be demonstrated by gel filtration on Sephadex G-100 Superfine, which also provided a means of isolating it. Gel filtration on Sephadex G-100 showed the molecular weights of the equine and bovine moyglobin aggregates to be about 35000 and 34000 respectively, thus supporting the hypothesis that they are dimers. This was confirmed for the equine myoglobin by ultracentrifugation meas...
Kim KH, Oang KY, Kim J, Lee JH, Kim Y, Ihee H.Here we report structural dynamics of equine myoglobin (Mb) in response to the CO photodissociation visualized by picosecond time-resolved X-ray solution scattering. The data clearly reveal new structural dynamics that occur in the timescale of ∼360 picoseconds (ps) and ∼9 nanoseconds (ns), which have not been clearly detected in previous studies.
Gunther MR, Sturgeon BE, Mason RP.The reaction between metmyoglobin (metMb) and hydrogen peroxide has been known since the 1950s to produce globin-centered free radicals. The direct electron spin resonance spectrum of a solution of horse metMb and hydrogen peroxide at room temperature consists of a multilined signal that decays in minutes at room temperature. Comparison of the direct ESR spectra obtained from the system under N(2)- and O(2)-saturated conditions demonstrates the presence of a peroxyl radical, identified by its g-value of 2.014. Computer simulations of the spectra recorded 3 s after the mixture of metMb and H(2)...
Van den Oord AH, Wesdorp JJ, Van Dam AF, Verheij JA.In commercial samples of equine myoglobin and samples of equine and bovine myoglobin prepared in the laboratory, a small amount of the protein was present as an aggregate. The presence of the myoglobin aggregate could be demonstrated by gel filtration on Sephadex G-100 Superfine, which also provided a means of isolating it. Gel filtration on Sephadex G-100 showed the molecular weights of the equine and bovine moyglobin aggregates to be about 35000 and 34000 respectively, thus supporting the hypothesis that they are dimers. This was confirmed for the equine myoglobin by ultracentrifugation meas...
Conley KE, Jones C.We test the hypothesis that myoglobin is important for O2 supply near the oxidative capacity of muscle. This hypothesis is evaluated with a simple model that incorporates the properties of heart and skeletal muscle tissue taken from steers and horses exercising at their maximum O2 consumption rate. These tissue samples allowed us to set the bounds on oxidative demand and O2 flux from red blood cells to the core of the muscle fiber, to estimate the blood and tissue capacities for O2 diffusion, and to define the capillary blood PO2 driving this O2 flux. A model combining blood convection with ti...
The study investigates the changes in meat organoleptic characteristics and sarcoplasmic proteins of 3 horse muscles during aging. Longissimus lumborum (LL), semimembranosus (SM) and semitendinosus (ST) muscles, were removed from 12 Italian Heavy Draft Horse carcasses and aged for 1, 3, 6, 9 and 14 days. The lowest values of hardness and chewiness were found in LL muscle. During aging, a decrease of hardness was observed in ST muscle reaching the lowest value at 14 days. 2DE revealed a decrease of 15 sarcoplasmic protein spots in all muscles. Muscle-differences were found at 14 days. An inc...
Hayashi T, Matsuo T, Hitomi Y, Okawa K, Suzuki A, Shiro Y, Iizuka T, Hisaeda Y, Ogoshi H.Horse heart myoglobin was reconstituted with mesohemin derivatives methylated at the 6- or 7-position to evaluate the role of the heme-6-propionate or heme-7-propionate side chain in the protein. The association and dissociation of the O(2) binding for the deoxymyoglobin with 6-methyl-7-propionate mesoheme are clearly accelerated. Furthermore, the myoglobin with 6-methyl-7-propionate mesoheme shows fast autoxidation from oxymyoglobin to metmyoglobin compared to the myoglobin with 6-propionate-7-methyl heme and the reference protein. These results indicate the 6-propionate plays an important ph...
Lin J, Merryweather J, Vitello LB, Erman JE.The kinetics of formation and dissociation of the horse metmyoglobin/azide complex has been investigated between pH 3.5 and 11.5. The ionic strength dependence of the reaction has been determined at integral pH values between 5 and 10. Hydrazoic acid, HN3, binds to metmyoglobin with a rate constant of (3.8 +/- 1.0) x 10(5) M-1 s-1. Protonation of a group with an apparent pKa of 4.0 +/- 0.3 increases the rate of HN3 binding 6.5-fold to (2.5 +/- 0.8) x 10(6) M-1 s-1. The ionizable group is attributed to the distal histidine, His-64. The azide anion, N-3, binds to metmyoglobin with a rate constan...
Ioannou A, Lambrou A, Daskalakis V, Pinakoulaki E.The coordination of nitrite in myoglobin (Mb) has been characterized by resonance Raman spectroscopy and the frequencies of the nitrite bound to the heme Fe as well to the 2-vinyl have been computed by density functional theory (DFT) calculations. The DFT Natural Bond Orbital (NBO) analysis and the extensive isotope-labeling in the resonance Raman experiments indicate that NO (O1NO2) is bound to the heme Fe via O1. Based on the vibrational characterization of the reversible transition between low and high spin FeONO/2-nitrovinyl species, we suggest that the key step that triggers the spin-chan...
Lloyd E, Mauk AG.Expression of recombinant horse heart myoglobin in Escherichia coli has been found to result in the production of both native and variable amounts (approximately 16-17% total) of two sulphmyoglobin isomers. The recombinant sulphmyoglobin produced consists primarily of the A and B isomers as identified by 1H NMR spectroscopy with no evidence for production of the C isomer. Conversion of recombinant sulphmyoglobin to the native protein can be achieved by reconstitution with protohaem IX. The possible relationship of this observation to recombinant expression of other heme proteins is discussed.
Miksovská J, Day JH, Larsen RW.Carbon monoxide binding to myoglobin was characterized using the photothermal beam deflection method. The volume and enthalpy changes coupled to CO dissociation were found to be 9.3+/-0.8 mL x mol(-1) and 7.4+/-2.8 kcal x mol(-1), respectively. The corresponding values observed for CO rebinding have the same magnitude but opposite sign: Delta V=-8.6+/-0.9 mL x mol(-1) and Delta H=-5.8+/-2.9 kcal x mol(-1). Ligand rebinding occurs as a single conformational step with a rate constant of 5 x 10(5) M(-1) s(-1) and with activation enthalpy of 7.1+/-0.8 kcal x mol(-1) and activation entropy of -22.4...
Holmgren N, Valberg S.Quantitative immunodiffusion in one dimension was performed in 6-mm Duran tubes containing a 1% Nobel agar solution and various dilutions of antisera. A series of dilutions of pure myoglobin in equine sera as well as plasma from horses with rhabdomyolysis were tested. Standard curves were prepared of the migration distance of the formed precipitate from the meniscus of the gel after 3, 6, 12, and 24 hours. The clearest line of precipitate was formed with a 1:20 dilution of antisera in agar. Standard curves were nonlinear and plasma myoglobin could be detected at 2 micrograms of myoglobin/ml or...
Mancini RA, Ramanathan R.Injection-enhancement of beef with lactate improves color stability; however, the mechanism is unclear. Thus, our objectives were to assess the effects of sodium lactate on equine myoglobin redox stability in vitro. Oxymyoglobin at pH 5.6 (50mM sodium citrate) and pH 7.4 (50mM sodium phosphate) was incubated at 4°C with lactate (0, 5, 10, 100, or 200mM) and myoglobin redox form was determined using absorbance spectra. Metmyoglobin formation at pH 5.6 and 7.4 was significantly (P<0.05) decreased by lactate at concentrations of 100 and 200mM. In general, increasing lactate concentration from...
Santucci R, Ascoli F, La Mar GN, Pandey RK, Smith KM.The reconstitution kinetics of horse heart myoglobin, as met-cyano derivative, with two synthetic hemins in which the 6- or the 7-propionate is replaced by a methyl group, has been investigated by circular dichroism, in order to gain information on the heme re-orientation process following the heme insertion into the globin pocket. The results obtained confirm that the preferred heme orientation places the sole propionate into the position occupied by the 6-propionate in the crystal structure, supporting the importance of the salt bridge occurring between this propionate and the basic CD3 resi...
Bronstein A, Marx A.Comparison of myoglobin structures reveals that protein isolated from horse heart consistently adopts an alternate turn conformation in comparison to its homologues. Analysis of hundreds of high-resolution structures discounts crystallization conditions or the surrounding amino acid protein environment as explaining this difference, that is also not captured by the AlphaFold prediction. Rather, a water molecule is identified as stabilizing the conformation in the horse heart structure, which immediately reverts to the whale conformation in molecular dynamics simulations excluding that structur...
Delvescovo B.This article describes the most common causes of urine discoloration. The review includes a description of the most common disorders causing hematuria, highlighting clinical presentation, treatments, and pathophysiology. Causes of hemoglobinuria and myoglobinuria together with their mechanisms of renal injury are also reviewed.
Mancini RA, Suman SP, Konda MK, Ramanathan R, Joseph P, Beach CM.Research focused on determining the fundamental mechanisms by which lactate influences color stability has not considered a direct effect of lactate on myoglobin. Thus, the objective of this study was to use Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry to examine lactate adduction to myoglobin. Equine oxymyoglobin and equine carboxymyoglobin (0.15mM) were incubated with sodium lactate (200mM) at 4 degrees C, pH 5.6 in 50mM sodium citrate buffer or at 37 degrees C, pH 7.4 in 50mM sodium phosphate buffer, simulating typical meat storage and physiological condition...
Valberg S, Jönsson L, Lindholm A, Holmgren N.Six horses with a history of recurrent exertional rhabdomyolysis (RER) (Horses A-F) and 7 control horses performed a submaximal and later a near-maximal treadmill exercise test. Blood samples were obtained before, during and after exercise and muscle biopsies were taken before and after exercise. At rest, plasma aspartate aminotransferase (AST) activities in horses with RER were above 95% confidence intervals for control horses. During submaximal exercise, 3 horses with RER (A, B and C) had much greater increases in plasma AST, creatine kinase (CK) and myoglobin concentrations than did Horses ...
Yamada S, Suruga K, Ogawa M, Hama T, Satoh T, Kawachi R, Nishio T, Oku T.The appearance of NO2- reducing activity of cytochrome c (Cyt c) upon heat denaturation was investigated with equine heart Cyt c. Denatured equine heart Cyt c (dCyt c), which was treated at 100 degrees C for 30 min, had NO2- reducing activity in the presence of dithionite and methylviologen in an aqueous solution under anaerobic conditions. In contrast, hemoglobin and myoglobin had no such activity under the same conditions. Using spectroscopic methods, we found that the appearance of this activity in the Cyt c was due to the following intramolecular changes: unfolding of the peptide chain, ex...
Folin M, Gennari G, Jori G.The irradiation of horse and sperm-whale Fe” or Fez’ myoglobins with visible light
showed that axial ligands that render the heme diamagnetic (e.g. 02, CO or CN-) endow the
hemoproteins with a marked photosensitivity. In contrast, high-spin myoglobins are unaffected by
visible light. These findings appear to be of general validity for all hemo-proteins and are in agreement
with the involvment of the triplet state of the heme as the reactive intermediate. In all cases, the overall
photoprocess occurs within a very narrow spatial range, leading to specific modification of these
photoox...
Valentín-Rodríguez C, López-Garriga J, Torres-Lugo M.Proteins are biological macromolecules which have a unique spatial conformation. Once this 3D spatial conformation is affected the protein's biological stability and activity can be severely limited. For these reasons, this investigation focuses on the effects of pre-polymeric solution components on the behavior of proteins to be encapsulated by the entrapment technique in anionic, cationic, and neutral hydrogel membranes. Equine skeletal muscle myoglobin (MMb), and equine heart myoglobin (HMb) were employed as model molecules. Three hydrogel morphologies were examined: methacrylic acid-poly(e...
