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Chem24 > Chem final > Flashcards

Chem final Flashcards

1
Q

What is the diff between myoglobin and hemoglobin

A
  1. myoglobin has 1 protein and 1 heme group (tertiary structure)
  2. hemoglobin is 4 subunits each with a protein and heme (quartenary structure)
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2
Q

Structurally, what are the similarities between Hb and myoglobin

A

Both are composed of a heme complex that have a coordinated Fe ….

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3
Q

T/F: Heme on its own is soluble

A

False

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4
Q

What ligands can attach to heme? (4)

A
  1. oxygen
  2. CO
  3. CO2
  4. Cyanide (cytochromes)
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5
Q

In regards to oxygen binding, what is the diff between myoglobin and Hb?

A
  1. Myoglobin has a higher affinity to oxygen, is monomeric, non cooperative binding
  2. Hemoglobin is tetrametric (4 domains), cooperative binding,
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6
Q

A rightward shift on an association curve for oxygen binding means?

A

less affinity for oxygen

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7
Q

When does myoglobin release oxygen?

A

When levels in muscles are very low

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8
Q

T/F: Hemoglobin can bind to oxygen multiple times

A

true

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9
Q

The sigmoidal shape of the hemoglobin curve signifies

A

cooperative binding

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10
Q

When does oxygen affinity increase for Hb?

A

as more oxygen is bound to heme (saturation increases)

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11
Q

Why do we see an increase in oxygen binding affinity with hemoglogin?

A

As oxygen binds, there is a shift in the heme and shift in protein structure
(Tense “t” state to Relaxed “r” state)

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12
Q

Binding always leads to ________ and with Hb this causes more _______

A

confirmational change
oxygen affinity

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13
Q

What is the R state?

A

4 oxygen have bound to Heme

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14
Q

what is the diff between fetal Hb and adult Hb

A

fetal has a higher affinity for oxygen

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15
Q

Why is there a higher affinity for oxygen in fetal Hb?

A
  1. Structural differences ( adult have 2 alpha and 2 beta)
  2. 2,3 BPG
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16
Q

Does 2,3 BPG bind to fetal Hg?

A

No

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17
Q

Why does 2,3 BPG do to adult Hb?

A

preturbe oxygen from binding to Heme

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18
Q

What charge is on histadine rings in adult Hb?

A

positive

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19
Q

What charge is on serine residue in fetal Hb?

A

no charge

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20
Q

Why is there no ion-dipole intermolecular force between 2,3 BPG and fetal hemoglobin

A

The distance is too great because the serine is small

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21
Q

2,3 BPG which stabalizes the structure of Hb, can also be a

A

competitive inhibitor

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22
Q

Shifting equilibrium to the left means? Would 2,3 BPG binding to adult Hb cause this?

A

higher affinity for oxygen
no; there would be a shift to the right

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23
Q

Where does 2,3 BPG come from

A

our bodies produce it

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24
Q

What does 2,3 BPG essentially do?

A

prevent conformational change and disallow more oxygen from binding

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25
Q

T/F: Both adult and fetal hemoglobin curves are sigmoidal

A

true

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26
Q

Shifting equillibrium to the left means oxygen favors the

A

T state

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27
Q

how can heme overcome binding of 2,3 BPG?

A

increasing pressure of O2

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28
Q

What are the 3 ways Co2 is transported throughout the blood? Which is primary?

A
  1. dissolved gas (10%)
  2. bicarb (blood buffering system)*
  3. bound to protein of the Hb
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29
Q

The n terminus of an amino acid is ________ while C is ________

A

nucleophilic
electrophilic

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30
Q

CO2 bound to Hb is called?

A

Carbaminohemoglobin

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31
Q

Where does CO2 bind on Hb?

A

the apoprotein, not the heme

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32
Q

High affinity for CO2 causes a _______ affinity for O2

A

low

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33
Q

What happens when RBC starts to bind to CO2

A

localized changes in pH of the environment (Bohr-Haldane Effect)

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34
Q

Oxygen dissociation is increased by (3)

A
  1. Increasing temp
  2. Lowering blood pH
  3. increasing partial Pco2
35
Q

What affects does increasing Pco2 have in the blood? (3)

A
  1. Increase H concentration
  2. protonates certain amino acid residues
  3. leads to conformational change of protein
36
Q

CO binds _____ times more strongly to heme than O2

A

200-300

37
Q

T/F: CO2 binds to the same site as oxygen and CO does not

A

False
CO binds to the same site as O2 on heme and CO2 does not
CO2 prevents conformational change

38
Q

Is binding reversible once CO bound to heme? how?

A

yes; increase the O2 levels or pressure

39
Q

When does fetal Hb dissipate in children and convert to adult Hb?

A

around 6 months

40
Q

What is Myoglobin

A

Protein that stores and transports oxygen in muscles for metabolic process to convert/product energy

41
Q

What determines myoglobins ability to bind or release oxygen?

A

cellular oxygen concentration

42
Q

Describe the relationship between myoglobin and NO?

A

The oxygen in myoglobin is used in the conversion of NO

43
Q

What intercepts free radical oxygen species from causing damage in the body?

A

Myoglobin

44
Q

Hemoglobin is ?

A

Protein that transports oxygen from lungs to tissues in the arterial circulation and transports CO2 from the tissue to lungs in the venous circulation

45
Q

Hemoglobin has a low affinity for these (4) compounds in the arteries but low in the veins

A

CO2
Phosphates
hydrogen
chloride

46
Q

Where does hemoglobin have a low affinity for oxygen?

A

in the veins

47
Q

What is the metal that is used to bind to oxygen in myoglobin and hemoglobin

A

Fe

48
Q

Which state is the active state for Fe

A

Fe2+ (ferrous)

49
Q

What is ferric iron?

A

Fe3+

50
Q

Describe the ligands that are attached to the Fe?

A

Electron rich (nonmetal or polyatomic)
(-) charges or lone pairs

51
Q

Why are ligands bond to Fe?

A

to stabalize the charge and to help solubilize

52
Q

How many coordination sites does Fe have

A

Six

53
Q

S orbitals like to form

A

Sigma bonds (single bonds)

54
Q

P orbitals like to form

A

pi bonds (multiple bonds)

55
Q

1s orbital and 3 p orbitals hybridize to form

A

sp3 OR (4 single bonds)
sp2 and 2p (3 single and 1 double bond)
sp and 2p (2 single and 2 double bonds)

56
Q

electron configuration of Fe

A

(Ar) 4s2 3d6

57
Q

electron configuration of Fe 2+

A

(Ar) 4s0 3d6

58
Q

Fe hybridized orbital
Where do the electrons remain? How many are there?

A

sp3 d2 3d
in the 3d orbital
6

59
Q

if all 6 coordination sites are filled on Fe, what is formed?

A

stable octahedral complex

60
Q

What are porphyrins?

A

hetertocyclic macrocycles composed of 4 modified pyrrole subunits connected by carbon bridges

61
Q

Are porphyrins aromatic?

A

yes

62
Q

What are porphyrins attached to heme?

A

to help with solubility

63
Q

Macro means

A

more than 10 atoms

64
Q

What is the pattern of double bonds on porphyrins?
What is this referred to?

A

every other carbon has a double bond
conjugation

65
Q

t/f conjugation makes aromatic compounds more stable

A

true

66
Q

t/f only mammals have porphyrin systems

A

false; mammals, bacteria, plants

67
Q

Porphyrins are _______ rich

A

electron

68
Q

What are the two reactions here?

A
  1. substitution
  2. substitution
69
Q

Reaction

A

substitution

70
Q

Reaction type

A
71
Q

Reaction types from right to left

A
  1. Elimination
  2. Elimination and Oxidation
  3. Redox
72
Q

The protoporphyrin portion attached to heme is known as

A

Protoporphryin IX

73
Q

What enzyme coordinates the Fe molecule to the center of the porphyrin?

A

Ferrochelatase

74
Q

Did the N donate electrons to the Fe or the Fe to the N? how many? Describe the position

A

Each N donates 2 electrons
The N are planar with the Fe

75
Q

Amino acids have alot of ____ and _____.
Both have alot of _________ and can donate ________

A

N and O
electrons
electron density

76
Q

Is heme hydrophobic or hydrophillic?

A

hydrophobic

77
Q

unbound inactive protein

A

apoprotein

78
Q

On the apoprotein is a ________ residue. What is its function? What does it cause?

A
  1. histadine
  2. bind to the bottom of the heme protein to make it more hydrophillic
  3. It kind of pulls on the Fe and makes it to where it sits below the plane
79
Q

Is there another histatine and apoprotein on top of the heme? Does it interact?

A

Yes
No because its too far away

80
Q

Where does Oxygen bind on heme?

A

the top of the structure (6th group)

81
Q

Differentiate between adult and fetal Hemoglobin. Up until when do babies produce fetal hemoglobin?

A

2 alpha and 2 beta
2 alpha and 2 gamma
6 months

82
Q

About how much lower does the Fe sit below the heme group when there is no oxygen bound? (deoxyhemoglobin)

A

0.4 A

83
Q

What happens to the structure when Oxygen binds to the Fe?

A

Fe is more planar with the heme protein

84
Q
A

Chem24 (5 decks)

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