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Biochem > Hemoglobin and Myoglobin > Flashcards

Hemoglobin and Myoglobin Flashcards

1
Q

Form that most CO2 is transported in

A

Bicarbonate

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2
Q

O2 binding protein in muscle that facilitates diffusion of O2 into tissue

A

Myoglobin

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3
Q

Structure of myoglobin

A

8 right handed alpha helices
(NO prolines)
Hydrophobic interior that protects heme from oxidation

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4
Q

Structural component of myoglobin that O2 binds to

A

Heme-poryphyrin ring and Fe2+ (Ferrous) atom

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5
Q

Ferrous atom

A

Fe2+

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6
Q

6 coordination ligands on Fe2+

A

4 to porphyrin ring, 1 to proximal His, 1 to oxygen

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7
Q

Other ligands that bind to the O2 binding site on myoglobin with greater affinity

A

Carbon monoxide, Hydrogen sulfide

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8
Q

State of iron in Hb/Mb that is protected from oxidation

A

Ferrous state Fe2+

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9
Q

State of iron in Hb/Mb that is exposed to oxidation

A

Ferric state Fe3+

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10
Q

A cofactor that is permanently associated with a polypeptide

A

Prosthetic group

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11
Q

Structure of hemoglobin

A

Looks like 4 myoglobin subunits but with poor sequence similarity
Quaternary structure = Heterotetramer

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12
Q

control of activity by ligand binding at a site other than the active site

A

Allosteric regulation

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13
Q

Area of the body where Hb is in Tense state and has low affinity for O2

A

Tissues

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14
Q

Area of the body where Hb is in relaxed state and has high affinity for O2

A

Respiratory area

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15
Q

Shape of saturation curve for myoglobin

A

Hyperbolic

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16
Q

Shape of saturation curve for hemoglobin

A

Sigmoidal

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17
Q

Proton binding has what effect on O2 affinity of Hb

A

Decreases O2 affinity

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18
Q

Phenomenon that describes how Hemoglobin’s oxygen binding affinity is inversely related both to acidity and to the concentration of carbon dioxide.

A

Bohr effect

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19
Q

Bohr effect states that:

A

Hb O2 affinity is inversely related to acidity and concentration of CO2

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20
Q

Decreased pH causes what effect on Hb O2 binding

A

Enhances O2 release –> stabilizes T state

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21
Q

Increased pH causes what effect on Hb O2 binding

A

Increases Hb binding for O2 –> stabilizes R state

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22
Q

CO2 form carbamate at this location on Hb

A

N-terminus of deoxy-Hb polypeptide (not at heme iron)

23
Q

2,3-BPG is specific to what type of cell

A

RBCs

24
Q

Effect of hypoxia on 2,3-BPG levels

A

levels increased due to less oxygen content (Hb less saturated)

25
Q

Effect of 2,3-BPG on O2 affinity for Hb

A

Facilitates unloading at tissue level

26
Q

Number of 2,3-BPG that bind per hemoglobin tetramer

A

1

27
Q

2,3-BPG stabilizes what state of Hb

A

Tense state

28
Q

Location where 2,3-BPG binds to deoxyHb

A

Cleft between the two beta chains

29
Q

Subunits of HbA

A

a2B2

30
Q

Subunits of HbA2

A

a2δ2

31
Q

Subunits of HbF

A

a2y2

32
Q

Expression of HbA

A

Most common adult Hb

33
Q

Expression of HbA2

A

Minor adult form (2-3%)

34
Q

Expression of HbF

A

Appears a few weeks post conception, persists a few months post birth

35
Q

Hb chains that resemble B and y chains

A

e (epsilon) chains

36
Q

Hb chains that resemble a chains

A

Zeta

37
Q

Hb form that has highest affinity for O2

A

HbF

38
Q

Hb form that 2,3-BPG binds less tightly

A

deoxyHbF

39
Q

Location where carbon monoxide binds on Hb

A

O2 binding site

40
Q

Appearance of carbonmonoxyHb

A

Cherry red/pink

41
Q

Hb form that contains ferric Fe3+ instead of Fe2+

A

Methemoglobin (MetHb)

42
Q

Enzymes involved in reducing amount of MetHb by reducing Fe3+ to Fe2+

A

Cytochrome b5 reductase,
NADPH methemoglobin reductase

43
Q

Congenital cause of increased Methemoglobin that is autosomal recessive

A

Genetic deficiency of cytochrome b5 reductase

44
Q

condition in which individuals compensate for high MetHb by making more RBCs than normal

A

Polycythemia

45
Q

Enzyme that is not at adult levels until 4 months of age and its deficiency can cause Blue baby syndrome

A

Cytochrome b5 reductase

46
Q

Mutation that allows Fe2+ to be oxidized to Fe3+ due to a tyrosine replacing histidine

A

Hemoglobin M (HbM) mutation

47
Q

treatments for high amount of methemoglobin

A

Supplemental O2 or Methylene blue

48
Q

Color associated with cyanosis

A

blue

49
Q

Color associated with methemoglobinemia

A

blue/chocolate-colored blood

50
Q

Color associated with carbon monoxide poisoning

A

cherry red/pinkish

51
Q

Color associated with hydrogen sulfide

A

ashen gray

52
Q

Effect of hyperventilation on O2 saturation of Hb

A

no significant effect

53
Q

Effect of hyperventilation on CO2 saturation

A

significantly reduced

Biochem (21 decks)

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