BICH 410 Lecture Notes - Lecture 14: Dissociation Constant, Myoglobin, Nfkb1

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6 Oct 2016

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Hydrophobic interactions help with the binding of oxygen due to the +2 state of iron. Kd more important than ka because it"s more concentration dependent on the two different molecules involved. Henry"s law: quantity of gas absorbed by liquid is proportional to the partial pressure of the gas above the liquid. Fractional saturation can be used for any ligand for concentration. Kd is equal to the concentration ligand at which half the sites occupied and is also de ned as p50. Yo2 increases as kd decreases - more sites are occupied the more af nity it has. This provides the s shape for the hemoglobin curve. Levels off towards the top because of the dif culty to get the last heme group bound to a oxygen molecule. The myoglobin curve is more rectangular (hyperbolic) because of its high af nity and one speci c site for binding oxygen. This is important for its function for oxygen storage for muscles.

Related Questions

1. Which non-covalent interaction is primarily
responsible for stabilizing a helices, Ã sheets, and Ã
turns?
a. Hydrophobic interactions.
b. Ion-pairing.
c. Hydrogen bonding.
d. Stacking of aromatic rings.
e. Van der Waals interactions.

2.Which is not associated with the formation of oligomers?
a. Increased stability compared to the dissociated subunits.
b. The formation of active sites between adjacent subunits.
c. Contact between the subunits that allows for changes in
quaternary structure when ligands bind. This can control
biological activity.
d. Increased efficiency by synthesizing smaller subunits
rather than a single chain the same size as the oligomer.
e. An enhanced ability to adopt F and ? angles outside the
common ranges.

3. Would you expect myoglobin that is injected
intravenously to perform the same function as
hemoglobin? Explain.
a. No, myoglobin cannot release oxygen as well to the
tissues.
b. No, because the heme of myoglobin binds oxygen at a
different coordination site.
c. No, because 2,3-BPG completely inhibits the binding of
oxygen to myoglobin.
d. Yes, in the blood myoglobin adopts a similar quaternary
structure as hemoglobin and binds oxygen with positive
cooperativity.
e. Yes, because both bind oxygen very easily in the lungs.

raspberryfly161

1. The dominant motif found in hemoglobin and myoglobin is: a) twisted beta sheet b) beta barrel c) helix-loop-helix d) 7-TM 2. Myoglobin has how many polypeptide chains? A) 1 b) 2 c) 3 d) 4 3. Structurally and functionally, hemoglobin closely resembles a(n) a) transmembrane protein b) mucopolysaccharide c) bile salt d) allosteric enzyme 4. The oxygen binding site in hemoglobin and myoglobin is called: a) BPG b) heme c) proximal-His d) N-terminal carbamate 5. The proximal His residue in hemoglobin and myoglobin binds to which atom or molecule? A) CO2 b) O2 c) Fe d) BPG 6. The distal His residue in hemoglobin and myoglobin binds to which atom or molecule? A) CO2 b) O2 c) Fe d) BPG 7. BPG binds to: a) N-terminal carbamate b) proximal His c) heme group d) central cavity 8. Indirect activity of CO2 is a result of increased concentration of which chemical species? A) BPG b) H+ c) heme iron d) distal His 9. Direct activity of CO2 is a result of binding to which molecular feature? A) the heme group b) the N-terminal ends of the 4 polypeptide chains c) the central cavity d) the proximal His 10. The sigmoidal, cooperative binding curve commonly observed for hemoglobin is a result of: a) competition between CO2 and O2 for heme binding. B) competition between heme and distal His for O2 binding c) competition between BPG and CO2 for binding at the central cavity site d) T to R transition 11. Hemoglobin has a tendency to release its oxygen to the tissues because: a) in this region pH is high and O2 concentrations are low b) in this region both pH and O2 concentrations are low c) in this region both pH and O2 concentrations are high d) there is much BPG in this region 12. Which statement about fetal hemoglobin is not true? A) fetal hemoglobin has gamma chains instead of beta chains b) fetal hemoglobin binds BPG less strongly than maternal hemoglobin c) fetal hemoglobin binds oxygen less strongly than maternal hemoglobin d) fetal hemoglobin binds oxygen more strongly than maternal hemoglobin 13. Which process is most responsible for the sickling of cells seen in sickle cell disease? A) aggregation of the oxygenated R form of hemoglobin-S to form insoluble fibers b) aggregation of the deoxygenated T form of hemoglobin-S to form insoluble fibers c) Hemoglobin-S does not contain heme d) Hemoglobin-S contains a mutant form of heme which will not bind oxygen 14. A person with sickle-cell trait is very unlikely to catch which disease? A) malaria b) colon cancer c) avian flu d) whooping cough 15. A person with a genetic defect which results in the synthesis of an insufficient amount of the alpha chain of hemoglobin is said to have which disease? A) alpha thalassemia b) beta thalassemia c) pernicious anemia d) Crohnâs disease

BICH 410 Lecture Notes - Lecture 14: Dissociation Constant, Myoglobin, Nfkb1

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