Podcast
Questions and Answers
What is the primary role of nonpolar interactions in the tertiary structure of myoglobin and hemoglobin?
What is the primary role of nonpolar interactions in the tertiary structure of myoglobin and hemoglobin?
- Facilitating heme binding to the apoprotein
- Enabling oxygen binding to the heme iron
- Contributing to the stability of the protein structure (correct)
- Promoting subunit interaction
Which interactions are involved in the binding of 2,3-bisphosphoglycerate to both adult and fetal hemoglobin?
Which interactions are involved in the binding of 2,3-bisphosphoglycerate to both adult and fetal hemoglobin?
- Hydrogen bonds (correct)
- Ionic bonds
- Hydrophobic interactions
- Covalent bonds
In which state does the iron need to be for oxygen binding to the heme iron in hemoglobin?
In which state does the iron need to be for oxygen binding to the heme iron in hemoglobin?
- Oxidized state
- Reduced state
- Ferrous state (correct)
- Ferric state
Which factor does NOT affect the oxygenation of hemoglobin in the lungs and in the tissues?
Which factor does NOT affect the oxygenation of hemoglobin in the lungs and in the tissues?
What is the result of mutations and deletions of globin genes that lead to disease?
What is the result of mutations and deletions of globin genes that lead to disease?
What is the therapeutic approach for carbon monoxide poisoning due to its competitive interaction with oxygen in hemoglobin?
What is the therapeutic approach for carbon monoxide poisoning due to its competitive interaction with oxygen in hemoglobin?
Which type of hemoglobinopathy is characterized by underproduction of one type of hemoglobin subunit?
Which type of hemoglobinopathy is characterized by underproduction of one type of hemoglobin subunit?
What is the point mutation in sickle cell anemia that leads to the substitution of Glu with Val at amino acid 6?
What is the point mutation in sickle cell anemia that leads to the substitution of Glu with Val at amino acid 6?
Which condition is characterized by significant fetal hemoglobin production continuing into adulthood, disregarding the normal shutoff point for adult-type hemoglobin?
Which condition is characterized by significant fetal hemoglobin production continuing into adulthood, disregarding the normal shutoff point for adult-type hemoglobin?
What type of mutation is associated with Hemoglobin Gun Hill?
What type of mutation is associated with Hemoglobin Gun Hill?
In uncontrolled diabetes, which hemoglobin form can increase more than twice normal?
In uncontrolled diabetes, which hemoglobin form can increase more than twice normal?
Which condition is characterized by chronic compensated hemolysis and an unstable mutant hemoglobin?
Which condition is characterized by chronic compensated hemolysis and an unstable mutant hemoglobin?
'Hb Barts' and 'HbH' are associated with which condition?
'Hb Barts' and 'HbH' are associated with which condition?
'HbE-Gower 1' and 'HbE Gower 2' are examples of which hemoglobinopathy?
'HbE-Gower 1' and 'HbE Gower 2' are examples of which hemoglobinopathy?
'Hereditary persistence of fetal hemoglobin (HPFH)' is characterized by the continued production of which type of hemoglobin?
'Hereditary persistence of fetal hemoglobin (HPFH)' is characterized by the continued production of which type of hemoglobin?
'Thalassemia' results in underproduction of which type of hemoglobin subunit?
'Thalassemia' results in underproduction of which type of hemoglobin subunit?
What is the main structural difference between myoglobin and hemoglobin?
What is the main structural difference between myoglobin and hemoglobin?
What is the significance of the steep slope in the oxygen binding curve of hemoglobin?
What is the significance of the steep slope in the oxygen binding curve of hemoglobin?
What effect does 2,3-bisphosphoglycerate (2,3-BPG) have on the oxygen binding curve of hemoglobin?
What effect does 2,3-bisphosphoglycerate (2,3-BPG) have on the oxygen binding curve of hemoglobin?
What is one of the conditions that leads to an increase in 2,3-BPG concentration?
What is one of the conditions that leads to an increase in 2,3-BPG concentration?
What effect does smoking have on the levels of 2,3-BPG in the blood?
What effect does smoking have on the levels of 2,3-BPG in the blood?
How does carbon monoxide (CO) affect the oxygen binding curve of hemoglobin?
How does carbon monoxide (CO) affect the oxygen binding curve of hemoglobin?
In carbon monoxide (CO) poisoning, what is the first line of treatment?
In carbon monoxide (CO) poisoning, what is the first line of treatment?
What is the structure of fetal hemoglobin (Hb F) compared to maternal Hb A?
What is the structure of fetal hemoglobin (Hb F) compared to maternal Hb A?
Which unit is equivalent to 1 mm of mercury in a barometer?
Which unit is equivalent to 1 mm of mercury in a barometer?
What can cause an increase in methemoglobin levels in response to certain drugs, H2O2, free radicals or mutations?
What can cause an increase in methemoglobin levels in response to certain drugs, H2O2, free radicals or mutations?
What are some factors that lead to an increase in 2,3-BPG concentration?
What are some factors that lead to an increase in 2,3-BPG concentration?
What is the main chemical difference between hemoglobin and methemoglobin?
What is the main chemical difference between hemoglobin and methemoglobin?
Which of the following is NOT a cause of methemoglobin formation?
Which of the following is NOT a cause of methemoglobin formation?
What is the primary role of the heme group in hemoglobin and myoglobin?
What is the primary role of the heme group in hemoglobin and myoglobin?
What structural feature is responsible for the movement of the iron atom and histidine residues in myoglobin upon oxygenation?
What structural feature is responsible for the movement of the iron atom and histidine residues in myoglobin upon oxygenation?
Which type of hemoglobin has a tetrameric structure composed of two non-identical subunits?
Which type of hemoglobin has a tetrameric structure composed of two non-identical subunits?
What is the function of the distal histidine in myoglobin and hemoglobin?
What is the function of the distal histidine in myoglobin and hemoglobin?
What effect does oxygenation have on the conformational state of hemoglobin?
What effect does oxygenation have on the conformational state of hemoglobin?
Which interactions are dominant and change little in the T-to-R conformational change of hemoglobin?
Which interactions are dominant and change little in the T-to-R conformational change of hemoglobin?
"HbE-Gower 1" and "HbE Gower 2" are examples of which condition?
"HbE-Gower 1" and "HbE Gower 2" are examples of which condition?
"Hereditary persistence of fetal hemoglobin (HPFH)" is characterized by the continued production of which type of hemoglobin?
"Hereditary persistence of fetal hemoglobin (HPFH)" is characterized by the continued production of which type of hemoglobin?
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Study Notes
- Dr. Zahi Damuni is a Professor of Biochemistry, contact details provided for office hours and questions.
- Learning objectives cover various aspects of myoglobin and hemoglobin, including their structures, oxygen binding, and the role of histidine residues.
- Hemoproteins are a group of specialized proteins containing heme as a tightly bound prosthetic group, functioning as electron carriers, part of the active site of catalase, and binding oxygen reversibly.
- Heme is a porphyrin ring with an iron atom at its center, forming covalent and coordinate bonds with the protein and oxygen.
- Myoglobin is a monomeric heme protein found in skeletal and heart muscle with a predominantly non-polar interior and charged amino acids on the surface.
- Myoglobin has a crevice that encloses a heme group, stabilized by hydrophobic interactions and hydrogen bonds.
- Oxygenation of myoglobin leads to a conformational change and movement of the iron atom and His F8 towards the plane of the ring.
- Hemoglobin is a tetrameric protein found mainly in RBCs with two non-identical subunits, each having a heme prosthetic group and going through structural changes upon oxygenation.
- Hemoglobin exists in two stable states, a "taut" or "tense" state with low oxygen affinity and a "relaxed" state with high oxygen affinity.
- Interactions between subunits in hemoglobin are dominated by hydrophobic and ionic interactions, with significant conformational changes upon oxygenation.
- Each pair of alpha and beta subunits stays relatively in the same position under both oxygenated and deoxygenated states, but twist relative to each other.
- Myoglobin and hemoglobin differ structurally, leading to their different functions: myoglobin binds and releases oxygen within muscle cells, while hemoglobin transports oxygen from the lungs to peripheral tissues and carbon dioxide from peripheral tissues to the lungs.
- Oxygen binding curves for both myoglobin and hemoglobin show different shapes and behaviors: myoglobin has a hyperbolic curve with low oxygen delivery capacity, while hemoglobin demonstrates cooperative binding and high oxygen delivery capacity.
- Binding of ligands like H+, CO2, and 2,3-bisphosphoglycerate affects hemoglobin's oxygen binding by shifting the equilibrium between the R and T states towards the T state, reducing oxygen saturation at a given partial pressure of oxygen.
- Hemoglobin functions as a vehicle for delivering oxygen efficiently from sites of high partial pressure to sites of low partial pressure.
- Myoglobin and hemoglobin have distinct structures, functions, and oxygen binding properties.
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