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20 Cards in this Set
- Front
- Back
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What is fractional saturation?
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The proportion of total sites filled.
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Dalton's Law
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Total pressure of gas mixture is sum of partial pressures
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Henry's Law
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Concentration of gas in solution proportional to partial pressure
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What are the pressure units?
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1 atm = 760 mm Hg = 101 kPa
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K sub D or equilibrium constant/dissociation constant equation
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= [L] [P]/ [PL]
where P is protein, L is ligand, and Ptotal = P + PL. Binding is "tight" when affinity is high, KD is low. |
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fractional saturation equation
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Θ = [L] / [L]+KD
Sites are half saturated (Θ=0.5) when [L]=KD |
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Does oxygen bind to heme embedded in protein reversibly?
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Yes.
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P50 is ....
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is PO2 where protein in 50% saturated (=KD)
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What happens when Fe(II) is oxidized to Fe(III)?
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O2 binding is abolished.
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What is cooperative binding?
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When multiple, interacting sites, whose affinity changes as more sites have O2 bound. An example of "allostery."
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What stabilizes the R state of Hb?
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O2 binding. R has a higher affinity for O2.
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What is the Hill equation?
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For a protein P having n sites that bind ligand L:
Θ = [L]n / ([L]n + Kd ) Log of equation = Log (Θ/ 1- Θ) = n log [L] – log Kd |
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How does pH affect O2 affinity for Hb?
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O2 affinity of Hb declines with pH (Bohr effect). Example: acidosis in exercising muscles induces O2 release (getting more oxygen to muscles)
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How does CO2 affect Hb?
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CO2 carbamylates Hb, stabilizes T-state, promotes release of O2
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How does BPG binding affect O2 affinity?
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BPG greatly reduces the affinity of Hb for O2. Important when at high altitudes.
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What mutation causes Sickle Cell Disease?
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Glu to Val at residue 6 of β subunits.
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What promotes sickling?
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Dehydration, exertion (hypoxia)
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Why are Hb levels low (50% normal)?
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Sickled cells are fragile and rupture easily.
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What concentration of CO is considered to be fatal?
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50 - 60 % COHB is considered fatal
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How would you treat CO poisoning?
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with excess O2. 100% O2 is good, hyperbaric oxygen (3 atm) is better
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