Metmyoglobin (Pressure Effects on Ligand Binding/Dilatometry) GABRIEL B
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18,8 Quaternary Structure of Proteins
570 CHAPTERt8 Amino Acids,Peptides, and Proteins 18,8Quaternary structure of proteins AIMS: Todefine the termssubunit dnd quaternarystructure. Io describethe quoternorystructure of hemoglobin.To distinguishomong oxyhemoglobin,deoxyhemoglobin, ond methemoglobin. Someproteins consist of more than one pollpeptide chain. Theseindiuid- ual chains are calledsubunits of the protein. Proteins composedof subunits In some proteins, polypeptide are said to haue quaternary structure. Many proteins have structures that chains aggregateto form contain subunits. Proteins consistingof dimers (two subunits), tetramers quaternary structures. (four subunits), and hexamers (six subunits) are fairly common. The pro- teins that comprise the individual subunits may be identical, or they may be different. Like the secondary and tertiary structures, the quaternary structure of a protein is determined by its primary structure. The pollpep- tide chains of subunits are held in place by the same forces that determine tertiary structure-hydrogen bonds, salt bridges, and sometimes disulfide bridges-except the forces are betweenthe polypeptide chains of the sub- units instead of within them. Hydrophobic aliphatic and aromatic side chains of subunits can aggregateto exclude water. Hemoglobin-the globular oxygen-transport protein of blood-is an example of a protein that has a quaternary structure. Max Perutz, also of the Medical ResearchCouncil laboratories,determined the structure of horse blood hemoglobin in 1959.Hemoglobin is a larger molecule than myoglo- bin. The hemoglobin molecule has a molar mass of 64,500.It contains about 5000 individual atoms, excluding hydrogens, in 574 amino acid residues. The quaternary structure of hemoglobin consistsof four peptide sub- units. TWo of the subunits are identical and are called the alpha subunits. -
The Role of Methemoglobin and Carboxyhemoglobin in COVID-19: a Review
Journal of Clinical Medicine Review The Role of Methemoglobin and Carboxyhemoglobin in COVID-19: A Review Felix Scholkmann 1,2,*, Tanja Restin 2, Marco Ferrari 3 and Valentina Quaresima 3 1 Biomedical Optics Research Laboratory, Department of Neonatology, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland 2 Newborn Research Zurich, Department of Neonatology, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland; [email protected] 3 Department of Life, Health and Environmental Sciences, University of L’Aquila, 67100 L’Aquila, Italy; [email protected] (M.F.); [email protected] (V.Q.) * Correspondence: [email protected]; Tel.: +41-4-4255-9326 Abstract: Following the outbreak of a novel coronavirus (SARS-CoV-2) associated with pneumonia in China (Corona Virus Disease 2019, COVID-19) at the end of 2019, the world is currently facing a global pandemic of infections with SARS-CoV-2 and cases of COVID-19. Since severely ill patients often show elevated methemoglobin (MetHb) and carboxyhemoglobin (COHb) concentrations in their blood as a marker of disease severity, we aimed to summarize the currently available published study results (case reports and cross-sectional studies) on MetHb and COHb concentrations in the blood of COVID-19 patients. To this end, a systematic literature research was performed. For the case of MetHb, seven publications were identified (five case reports and two cross-sectional studies), and for the case of COHb, three studies were found (two cross-sectional studies and one case report). The findings reported in the publications show that an increase in MetHb and COHb can happen in COVID-19 patients, especially in critically ill ones, and that MetHb and COHb can increase to dangerously high levels during the course of the disease in some patients. -
Strategies for Increasing Oxidative Stability of (Fresh) Meat Color
O X I D A T I V E P R O C E S S E S I N M E A T Strategies for Increasing Oxidative Stability of (Fresh) Meat Color CAMERON FAUSTMAN*, W.K.M. CHAN, M.P. LYNCH and S.T. JOO Introduction moglobin and myoglobin) and for electron transport during respiration (cytochromes) in the living animal. Skeletal Fresh meat color is determined by the oxidation status muscles which obtain energy primarily by aerobic means of myoglobin. Several reviews of myoglobin chemistry and contain relatively high concentrations of heme proteins when meat color stability, including cured and/or cooked meat compared to those which depend primarily on anaerobic color, have been published (Livingston and Brown, 1981; glycolysis. Giddings, 1977; Faustman and Cassens, 1990a; Renerre, Of the heme proteins found in post-mortem skeletal 1990; Cornforth, 1994). The purpose of this presentation is muscle, myoglobin is the most important for considerations to emphasize recent research findings which impact the oxi- of meat color. The majority of hemoglobin found in the liv- dative stability of myoglobin in fresh meat. Specific atten- ing animal is lost during slaughter as a result of exsan- tion is given to metmyoglobin reduction and antioxidant ap- guination. Some blood is retained in meat (Fleming et al., proaches for minimizing oxymyoglobin oxidation. 1960) and Warriss and Rhodes (1977) estimated the aver- Maintenance of oxymyoglobin and thus a desirable age residual blood content of butcher’s meat to be 0.3%. appearance in fresh meat has significant economic impact. Han et al. (1994) recently published a procedure for deter- Liu et al. -
Relationship Between Beef Colour and Myoglobin
Relationship between beef colour and myoglobin Author: S.H.J.M . Dobbelstein Registration number: 790608185120 Subject code: P052-754 (24 stp) P052-274 (1 stp) Supervisors: Dr. Ir. E.U. Thoden van Velzen (A&F) Dr. Ir.J.P.H . Linssen (WUR) Examiner: Prof. Dr. Ir. M.A.J.S. van Boekel Report 474 Preface This thesis is part of my Master in Food Technology at Wageningen UR. This subject was carried out at the Quality in Chains department of Agrotechnology & Food Innovations (A&F) in co opération with the Product Design and Quality Management Group of Wageningen UR. I worked on this thesis from January till August 2005 at A&F. During my study I became interested in Meat Science and the subject of this thesis fits perfecdy to my interests. During my stay at A&F I had all freedom and responsibility to conduct my research. This made I really enjoyed working on this thesis. Moreover, it increased my knowledge of Meat Science very much. I would like to thank Ulphard Thoden van Velzen, my supervisor at A&F, and Jozef Linssen, my supervisor at the University, for their help during this study. I also want to thank Ronald Holtmaat from ProMessa (Deventer, NL) who kindly provided the meat for this study. Furthermore I would like to thank Aart Zegveld, Dianne Somhorst and Janny Slotboom who helped me with my practical work at A&F. ©Agrotechnology &Foo d Innovations B.V .Membe r of Wageningen UR Abstract The most important quality attribute of fresh beef is its colour. -
Concentration of NADH-Cytochrome B5 Reductase in Erythrocytes of Normal and Methemoglobinemic Individuals Measured with a Quantitative Radioimmunoblotting Assay
Concentration of NADH-cytochrome b5 reductase in erythrocytes of normal and methemoglobinemic individuals measured with a quantitative radioimmunoblotting assay. N Borgese, … , G Pietrini, S Gaetani J Clin Invest. 1987;80(5):1296-1302. https://doi.org/10.1172/JCI113205. Research Article The activity of NADH-cytochrome b5 reductase (NADH-methemoglobin reductase) is generally reduced in red cells of patients with recessive hereditary methemoglobinemia. To determine whether this lower activity is due to reduced concentration of an enzyme with normal catalytic properties or to reduced activity of an enzyme present at normal concentration, we measured erythrocyte reductase concentrations with a quantitative radioimmunoblotting method, using affinity-purified polyclonal antibodies against rat liver microsomal reductase as probe. In five patients with the "mild" form of recessive hereditary methemoglobinemia, in which the activity of erythrocyte reductase was 4-13% of controls, concentrations of the enzyme, measured as antigen, were also reduced to 7-20% of the control values. The concentration of membrane-bound reductase antigen, measured in the ghost fraction, was similarly reduced. Thus, in these patients, the reductase deficit is caused mainly by a reduction in NADH-cytochrome b5 reductase concentration, although altered catalytic properties of the enzyme may also contribute to the reduced enzyme activity. Find the latest version: https://jci.me/113205/pdf Concentration of NADH-Cytochrome b5 Reductase in Erythrocytes of Normal and Methemoglobinemic -
Myoglobin from Equine Skeletal Muscle
Myoglobin from equine skeletal muscle Catalog Number M0630 Storage Temperature –20 C CAS RN 100684-32-0 Precautions and Disclaimer This product is for R&D use only, not for drug, Product Description household, or other uses. Please consult the Safety Molecular mass:1 17.6 kDa Data Sheet for information regarding hazards and safe Extinction coefficient:2 EmM = 12.92 (555 nm) handling practices. pI:3 7.3 (major component) and 6.8 (minor component) Preparation Instructions Myoglobin from horse skeletal muscle is a single chain This protein is soluble in water (10 mg/ml), yielding a heme protein containing 153 amino acid residues. It clear, red brown solution. posesses no disulfide bridges or free -SH groups. Myoglobin contains 8 variously sized right-handed References helical regions, joined by non-ordered or random coil 1. Darbre, P.D. et al., Comparison of the myoglobin of regions. These 8 helices (A, B, C, D, E, F, G, and H) the zebra (Equus burchelli) with that of the horse are folded back on top of one another, and the heme is (Equus cabalus). Biochim. Biophys. Acta, 393(1), situated between helices E and F. The heme is almost 201-204 (1975). totally buried. Only the edge carrying the two 2. Bowen, W.J., The absorption spectra and extinction hydrophylic propionic acid groups is exposed. The coefficients of myoglobin. J. Biol. Chem., 179, 235- heme is held in position by a coordinating complex 245 (1949). between the central Fe(II) atom and 2 histidine residues 3. Radola, B.J., Isoelectric focusing in layers of (on helices E and F, respectively). -
1 Hemoglobin Catalyzes ATP-Synthesis in Human
Hemoglobin catalyzes ATP-synthesis in human erythrocytes: A murburn model Abhinav Parashar*, Vivian David Jacob, Daniel Andrew Gideon, Kelath Murali Manoj* *Corresponding authors, Satyamjayatu: The Science & Ethics Foundation, Snehatheeram, Kulappully, Shoranur-2, Kerala, India-679122. [email protected] Abstract: Blood hemoglobin (Hb) is the most abundant globular protein in humans, known to transport oxygen. Erythrocytes have ~10-3 M concentration levels of ATP in steady-state and we estimate that this high cannot be formed from 10-4 - 10-7 M levels of precursors via substrate- level phosphorylation of glycolysis. To account for this discrepancy, we propose that Hb serves as a ‘murzyme’ (a redox enzyme working along the principles of murburn concept), catalyzing the synthesis of the major amounts of ATP found in erythrocytes. This proposal is along the lines of our earlier works demonstrating DROS (diffusible reactive oxygen species) mediated ATP- synthesis as a thermodynamically and kinetically viable mechanism for physiological oxidative phosphorylation. We support the new hypothesis for Hb with theoretical arguments, experimental findings of reputed peers and in silico explorations. Using in silico methods, we demonstrate that adenoside nucleotide and 2,3-bisphosphoglycerate (2,3-BPG) binding sites are located suitably on the monomer/tetramer, thereby availing facile access to the superoxide emanating from the heme center. Our proposal explains earlier reported in situ experimental findings/suggestions of 2,3-BPG and ADP binding at the same locus on Hb. The binding energy is in the order of 2,3-BPG > NADH > ATP > ADP > AMP and agrees with earlier reports, potentially explaining the bioenergetic physiology of erythrocytes. -
As Well As Whale Metmyoglobin in 0.1 M Deuterated Phosphate at Pd 7 and at 31'C
NUCLEAR MAGNETIC RESONANCE STUDIES OF HEMOGLOBINS, III. EVIDENCE 1OR THE NONEQUIVALENCE OF a- AND (3-CHAINS IN AZIDE DERIVATIVES OF AME'TIIEMOGLOBINS* BY DONALD G. DAVIS, SAMUEL CHARACIHEt AND) CHIEN Ho DEPARTMENT OF BIOPHYSICS AND MICRtOBIOLOGY, UNJVI;RSI'IY' OlF Pl-ITT'SlBURGH, PITTSBURGH, PENNSYLVANIA Communicated by George Scatchard, June 12, 1969 Abstract.-Nuclear magnetic resonance spectroscopy (100-MN1Hz proton) was used to study the low-spin (S = 1/2) azide derivatives of human adult (a2(32), human fetal (C2Y2), Zurich (a2,f263 HiS - Arg), and horse (a2'(32') methemoglobins, as well as whale metmyoglobin in 0.1 M deuterated phosphate at pD 7 and at 31'C. The experimental results indicate that the azide-bound heme groups of the a- and (-chains in human adult methemoglobin and of the a- and 'y-chains in fetal methemoglobin are not equivalent. The affinity of the (3- or e-chain for azide ion appears larger than that of the a-chain. The nuclar magnetic resonance spectrum of hemoglobin Zfirich shows that the environment of the azide-heme complex in the abnormal (-chain is altered by the substitution of arginine for histidine in the (3-63 position, while the a-heme environment remains unaffected. Introduction.-The chief physiologic function of hemoglobin is to transport molecular oxygen from lung to tissues by virtue of its ability to combine revers- ibly with oxygen. Hemoglobin is a protein molecule consisting of four subunits (normally two a-chains and two (3-chains). Each of the four subunits has a heme group, and these heme groups are the "active centers" of hemoglobin. -
The First Korean Family with Hemoglobin-M Milwaukee-2 Leading to Hereditary Methemoglobinemia
Case Report Yonsei Med J 2020 Dec;61(12):1064-1067 https://doi.org/10.3349/ymj.2020.61.12.1064 pISSN: 0513-5796 · eISSN: 1976-2437 The First Korean Family with Hemoglobin-M Milwaukee-2 Leading to Hereditary Methemoglobinemia Dae Sung Kim1, Hee Jo Baek1,2, Bo Ram Kim1, Bo Ae Yoon1,2, Jun Hyung Lee3, and Hoon Kook1,2 1Department of Pediatrics, Chonnam National University Hwasun Hospital, Hwasun; 2Department of Pediatrics, Chonnam National University Medical School, Gwangju; 3Department of Laboratory Medicine, Chonnam National University Hwasun Hospital, Chonnam National University Medical School, Gwangju, Korea. Hemoglobin M (HbM) is a group of abnormal hemoglobin variants that form methemoglobin, which leads to cyanosis and he- molytic anemia. HbM-Milwaukee-2 is a rare variant caused by the point mutation CAC>TAC on codon 93 of the hemoglobin sub- unit beta (HBB) gene, resulting in the replacement of histidine by tyrosine. We here report the first Korean family with HbM-Mil- waukee-2, whose diagnosis was confirmed by gene sequencing. A high index of suspicion for this rare Hb variant is necessary in a patient presenting with cyanosis since childhood, along with methemoglobinemia and a family history of cyanosis. Key Words: Hemoglobin M-Milwaukee-2, methemoglobinemia, cyanosis, congenital hemolytic anemia INTRODUCTION tion pathway.6 Methemoglobinemia occurs when metHb lev- els exceed 1.5% in blood.7 Hereditary methemoglobinemia is Hemoglobinopathy refers to abnormalities in hemoglobin often caused by methemoglobin reductase enzyme deficiency, -
AMSA Meat Color Measurement Guidelines
AMSA Meat Color Measurement Guidelines Revised December 2012 American Meat Science Association http://www.meatscience.org AMSA Meat Color Measurement Guidelines Revised December 2012 American Meat Science Association 201 West Springfield Avenue, Suite 1202 Champaign, Illinois USA 61820 800-517-2672 [email protected] http://www.meatscience.org CONTENTS Technical Writing Committee .................................................................................................................... v Preface ..............................................................................................................................................................vi Section I: Introduction ................................................................................................................................. 1 Section II: Myoglobin Chemistry ............................................................................................................... 3 A. Fundamental Myoglobin Chemistry ................................................................................................................ 3 B. Dynamics of Myoglobin Redox Form Interconversions ........................................................................... 3 C. Visual, Practical Meat Color Versus Actual Pigment Chemistry ........................................................... 5 D. Factors Affecting Meat Color ............................................................................................................................... 6 E. Muscle -
Evidence of the Existence of a High Spin Low Spin Equilibrium in Liver Microsomal Cytochrome P450, and Its Role in the Enzymatic Mechanism* H
CROATICA CHEMICA ACTA CCACAA 49 (2) 251-261 (1977) YU ISSN 0011-1643 CCA-996 577.15.087.8 :541.651 Conference Paper Evidence of the Existence of a High Spin Low Spin Equilibrium in Liver Microsomal Cytochrome P450, and its Role in the Enzymatic Mechanism* H. Rei:n, 0. Ristau, J. Friedrich, G.-R. Jiinig, and K. RuckpauL Department of Biocatalysis, C'entral Institute of Molecular Biology, Academy of Sciences of the GDR 1115 Berlin, GDR Received November 8, 1976 In rabbit liver microsomal cytochrome P450 a high spin (S = = 5/2) low spin (S = 1/2) equilibrium has been proved to exist by recording temperature difference spectra in the Soret and in the visible region of the absorption spectrum of solubilized cytochrome P450. In the presence of type II substrates the predominantly low spin state of cytochrome P450 is maintained, only a very small shift to lower spin is observed. Ligands of the heme iron, such as cyanide and imidazole, pr9duce a pure low spin state and therefore in the presence of these ligands no temperature difference spectra can be obtained. In the presence of type I substrate, however, the spin equilibrium is shifted to the high spin state. The extent of this shift (1) depends on specific properties of the substrate and (2) it is generally relatively small, up to about 80/o in the case of substrates investigated so far. INTRODUCTION The first step in the reaction cycle of cytochrome P450 is the binding of the substrate to the enzyme. The binding is connected with changes in the absorption spectrum especially in the Soret region from which the binding constant can be evaluated1• Moreover, in the case of the so far best known cytochrome P450 from Pseudomonas putida it has been established that at substrate binding the low spin state of the heme iron is changed into the high spin state2• In the presence of camphor, a specific substrate, bacterial cytochrome P450 exhibits in the EPR spectrum g values of 8, 4, and 1.8, typical of high spin ferric heme iron in a strong distorted rhombic field. -
Processing Effects on Fresh and Frozen Meat Color Dale L
Processing Effects on Fresh and Frozen Meat Color Dale L. Huffman* Introduction pletely filled with hydrophobic groups. Deep in the hy- drophobic interior is a cleft where heme is located. According In recent years there has been a considerable amount of to Adam (1976) the globin moiety does not assume its native interest in further processing of fresh meat. The primary con- conformation unless it is complexed with heme. The heme sideration in evaluating freshness is color. The purpose of this group serves to stabilize the configuration of the myoglobin manuscript is to assess the present status of processed fresh molecule. The heme is oriented in such a way that the vinyl meat color. groups are buried in the hydrophobic interior and the car- boxyl group of the propionic acids extend from the interior Myoglobin and color in fresh meat where they form part of the polar surface. Both the propionic Although a number of pigments are present in muscle, acid side chains are believed to be hydrogen bonded to myoglobin is generally the only pigment present in large serine, histidine, and arginine amino acid residues on the enough quantities to color meat. Hemoglobin constitutes globin moiety (Antonini and Brunori, 1971). According to 12-30% of the total muscle pigment. Since the two pigments Govindarajan (1973) the entire inner portion of the heme is have similar spectral properties, myoglobin alone is used as surrounded by side chains of nonpolar amino acids. It is due an index of fresh meat color. to these nonpolar surroundings that ferrous iron (Fef2) in The myoglobin content of muscle tissue varies not only be- myoglobin is able to reversibly combine with oxygen (Govin- tween species but between age group as well as muscle types darajan, 1973).