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RC Test 2 > B4.024 - Myoglobin and Hemoglobin > Flashcards

B4.024 - Myoglobin and Hemoglobin Flashcards

1
Q

biological role of Mb

A

stores O2 in muscle

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2
Q

biological role of Hb

A

red blood cells, transports O2 from lungs to tissues

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3
Q

what is the % of similarity between Hb and Mg

A

38%

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4
Q

quaternary structure of Hb and Mg

A

Hb - tetramer (alpha 2, X2) Mg - monomer

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5
Q

what form of Hb can assemble but doesnt function

A

B4

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6
Q

free heme binds what more tightly than O2

A

CO

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7
Q

what hinders CO binding

A

protein

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8
Q

what role does protein have in heme prosthetic groups

A

hinders CO binding Inhibits oxidation of iron

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9
Q

describe the color change of hemoglobin

A

when bound to oxygen it has a red color when not bound to oxygen it has a blue color

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10
Q

describe the curve of oxygen binding to Hb

A

its sigmoidal because of cooperative binding

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11
Q

how many binding events does Hb have

A

4 - 4 binding sites

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12
Q

what does a Mg binding curve look like

A

simple hyperbolic

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13
Q

which binds more tightly to oxygen Hb or Mg and why

A

Mg because you need to steal it away to give to muscle

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14
Q

what causes cooperative binding

A

conformational change with oxygen binding offers higher affinity

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15
Q

where does BPG come from

A

synthesized in erythrocytes from glucose

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16
Q

what does BPG do with Hb

A

can bind to Hb (has many binding sites)

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17
Q

describe BPG charge

A

its very negatively charged allowing it to bind to positively charged AAs

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18
Q

what does BPG do with Hb

A

binds to low affinity form drives reaction back to deoxy form of Hb

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19
Q

what would the Hb binding curve look like without BPG

A

the Mg curve

20
Q

when is BPG upregulated and lost

A

up-regulated with hypoxia lost during blood storage (contributes to shelf life) because its used up for energy

21
Q

how is BPG binding different in fetal Hb

A

not as high of an affinity for binding, because of higher need for taking oxygen from moms blood

22
Q

what does H+ do with Hb

A

weakens oxygen binding

23
Q

what does CO2 do with Hb

A

allosteric inhibitor of O2 affinity

24
Q

describe binding of CO2

A

covalent and reversible binding at N terminal amines

25
Q

what do Mb and Hb moonlight as

A

enzymes changing NO to NO3 this disables heme so it cant bind oxygen

26
Q

describe the color change in blood due to NO3 binding to heme and blocking oxygen binding

A

it turns chocolate brown

27
Q

how does altitude affect Hb binding

A

higher altitude has less oxygen concentration oxygen in body will diffuse back out

28
Q

what does the presence of Fe3+ mean for the Hb binding curve

A

never can get fraction binding all the way to one so the curve is lower

29
Q

antidote to drugs that oxidize Fe2+?

A

methylene blue

30
Q

describe symptoms of CO poisoning at <10% >10%, 20%, 25%, 30% COHb level

A

<10% - headache dizziness >10% - slight headache 20% - slight headache, loss of judgment 25% - frontal headache 30% - dizziness, nausea, convulsions

31
Q

why is CO poisoning so toxic

A

binds any protein with heme binds at extremely low [CO] substoichiometric conditions it still has effect

32
Q

what does it mean that CO has effects at substoichiometric conditions

A

only one bound CO causes an effect, dont need 4

33
Q

what does CO do to heme

A

precules O2 binding to this site enhances O2 binding at other sites

34
Q

what does the CO Hb binding curve look like

A

like Mb but lower bc it cant bind as much O2 but cant release what it has

35
Q

what is thalassemia

A

loss of one subunit stoichiometry gets messed up can aggregate and precipitate causes anemia

36
Q

what are hemoglobinopathies

A

sickle cell point mutation affecting Hb

37
Q

what does Hb scavenge

A

NO, causes spike in BP

38
Q

if any NO makes it too far what happens

A

Mg sequesters it to block it from messing with ETC

39
Q

what mops up NO

A

Free Hb

40
Q

what are things people are trying to make synthesized Hb

A

Covalently cross link tetramer copy Hb of ocean mammals increase size to avoid NO zone

41
Q

what type of secondary structure is this and how many domains

A

alpha helix, random coil

1 domain

42
Q

why AAs would you expect on the interior of this and on the surface

A

hydrophobic - interior

hydrophilic - exterior

43
Q

A. Green positions

B. Yellow positions

C. white positions

D. positions with a dash

A

C - white positions

44
Q

what happens to Hb curve as pH decreases?

The O2 affinity higher or lower?

Midpoint of new curve higher or lower for pO2?

How does this make sense?

A
45
Q

what happens to the Hb cureve with Hb Kansas?

A
46
Q
A

RC Test 2 (19 decks)

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