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MCB II Block 2 > Globular Proteins > Flashcards

Globular Proteins Flashcards

1
Q

what gas does hemoglobin trap

A

oxygen

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2
Q

heme is protoporphyrin with

A

iron in it

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3
Q

structure of myoglobin

A

8 alpha helixes

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4
Q

heme is placed b/w what segments of myoglobin

A

F & E

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5
Q

iron and oxidation

A

If iron Fe2+ is oxidized to Fe3+ it will no longer be able to bind oxygen

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6
Q

when iron is oxidized what happens

A

it disables the heme

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7
Q

myoglobin function

A

storage device for oxygen

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8
Q

hemoglobin function

A

has to pick up and deliver oxygen efficiently

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9
Q

how does hemoglobin pick up oxygen and deliver it efficiently

A

at high O2 pressure it has high affinity for O2, at low pO2 it releases O2 - has low affinity for it

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10
Q

hemoglobin structure

A

mixture of polypeptide
alpha and beta
4 globin chains

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11
Q

how is hemoglobin sequence different from myoglobin

A

myologin has proximal His and distal his

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12
Q

oxyhemoglobin

A

iron perferclty in plane of heme

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13
Q

when oxyhemoglobin

A

open door for heme to bind oxygen

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14
Q

in tissues what happens to iron group to release oxygen

A

proximal his is used as a leash, protein can change conformation and when iron is moved out of plane of heme then oxygen is released

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15
Q

hemoglobin is wht kind of protein

A

allosteric

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16
Q

what is allosteric protein

what is it in regards to hemoglobin

A

binding of a ligand to one site affects the binding to other sites
for oxygen binding to hemoblogbin - has four sites
binding of oxygen to one subunit affects binding to others

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17
Q

what is homotropic

A

The normal ligand of the protein is the allosteric regulator.

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18
Q

what is heterotropic

A

A different ligand affects binding of the normal ligand.

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19
Q

in regards to allosteric protein binding it can be

A

positive or negative

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20
Q

cooperativity is what kind of regulation

A

positive homotropic regulation

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21
Q

does myoglobin have cooperativity

A

no

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22
Q

does hemoglobin have cooperativity

A

yes

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23
Q

if you increase the pressure of oxygen what will happen to conformation of hemoglobin

A

it will increase the binding of hemoglobin to oxygen

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24
Q

if O2 levels are low what happens to affinity of hemoglobin and oxygen

A

it has low affinity so it can release the oxygen in the tissues

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25
Q

low affinity state of hemoglobin is called

A

t state

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26
Q

t state stands for

A

tense state

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27
Q

does t state ever happen

A

not in reality, its just in theory

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28
Q

what happens in t state

A

low oxygen affinity

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29
Q

binding of oxygen to one subunit in heme does what

A

increases affinity of the other, so oxygen can more easily bind another heme group

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30
Q

what does r state stand for

A

relaxed state

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31
Q

cooperativity of oxygen binding derives from

A

conformational changes in tertiary structure of each globin chain

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32
Q

conformational change from t state makes it become

A

r state with higher afinity

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33
Q

binding of 1st oxygen has what rate

A

its low - b/c energy needed to make first adjustment in conformation

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34
Q

what is the state with low affinity for o2

A

t state

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35
Q

what is the state with high affinity for o2

A

r state

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36
Q

describe properties of t state

A

Low oxygen affinity
Resists the binding of oxygen
Deoxygenated
More salt bridges

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37
Q

describe properites of r state

A

High oxygen affinity
Binding of oxygen is facilitated
Oxygenated
Fewer salt bridges

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38
Q

describe the middle of hemoglobin in structure of t and r state

A

the middle of t state looks more open the middle of r state looks more close

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39
Q

what are the three ways hemoglobin binding for oygen is decreased

A
    • low pH (Bohr effect)
    • binding of 2,3 bisphosphoglycerate
    • covalent attachment of carbon dioxide (CO2)
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40
Q

Co2 gets hydrated and produces

A

carbolic acid

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41
Q

carbolic acid produces

A

more hydrogen and lowers ph

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42
Q

what does co2 do in regards to ph

A

it lower ph

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43
Q

how does co2 affect oxygen

A

it lowers ph which decreases binding for oxygen

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44
Q

2,3 bisphosphoglycerate - what is it

A

conjugate base

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45
Q

if ph is increased what happens to affinity for oxygen

A

it increases

46
Q

what is ph of blood in lungs

A

7.6

47
Q

what is ph of blood in tissues

A

7.2

48
Q

if ph is decreased what happens to affinity for oxgyen

A

it decreases

49
Q

what is bohr effect

A

describing how ph affects affinity for oxygen

50
Q

one waste product of tissues is

A

co2

51
Q

draw reaction of CO2 with water

A

CO2 + H2O ↔ HCO3− + H+

52
Q

carbonic anyhydrase does what

A

decreases ph of cell

53
Q

what does H+ do to hemoglobin

A

it binds to hemoglobin and stabilizes the T state

54
Q

how does hemoglobin act as buffer

A

H+ can bind to it

55
Q

draw out bohr affect, list all the steps

A

pg 15

56
Q

histidine does what

A

accepts the proton and is protonated - when it is protonated it interacts w/ carboxylase an allows other reactions to occur → more salt bridges than in the Hb R state

57
Q

2,3-bisphosphoglycerate is an acid or base

A

acid

58
Q

what form is 2,3-bisphosphoglycerate present in body

A

conjugate base

59
Q

what produces 2,3-bisphosphoglycerate

A

RBC

60
Q

when hemoglobin is in T state what fits perfectly

A

2,3-bisphosphoglycerate

61
Q

when t state is what kind of charge

A

positive charges

62
Q

look at structure of 2,3-bisphosphoglycerate and think about the negative charges and how it binds to t state

A

pg 17

63
Q

at sea level what is level of saturation of hemoglobin in lungs

A

100%

64
Q

when at high altitude what happens to oxygen saturation in lungs

A

pressure of oxygen in lungs is lower

oxygen levels decreased, so there is less release of oxygen

65
Q

how much oxygen is released at sea level

A

38%

66
Q

what does body do to compensate at high altitude

A

body produces more BPG

67
Q

what does BPG stand for

A

2,3-bisphosphoglycerate

68
Q

if body produces more BPG what does it do to oxygen

A

releases more oxygen

69
Q

anemia compensaes by producing more

A

2,3 BPG

70
Q

when mutation in pyruvae kinase have high levels of

A

2,3 BPG

71
Q

in fetus produce what hemoglobin

A

hemoglobin F

72
Q

If remove a pos. charge in hole of hemoglobin one of the pos. charges come from his - so if you have hemoglobin without the his. the binding will decrease - don’t want that.

A

increases oxygen in tissues

73
Q

fetal hemoglobin having less affinity for 2,3, BPG has higher affinity for

A

oxygen

74
Q

mother vs baby oxygen

A

mother has lower affinity for oxygen than baby so oxygen can migrate to baby

75
Q

sickle cell anemia is due to mutation in

A

hemoglobin

76
Q

sickle cell anemia provides protection against

A

malaria

77
Q

what is mutation in sickle cell

A

Glu6 → Val in the beta chain of Hb

78
Q

when glutamic acid is changed to valine in hemoglobin what happen

A

the hemoglobin has hydrophobic bump

79
Q

hemoglobin with the bump interacts with other peplomers and form a polymer and this does what

A

can clump capillaries, the blood cell is sickled shape

80
Q

what is common treatment for sickle cell anemia

A

hydorxyurea

81
Q

what does hydroxyurea do

A

prevents or makes less frequent the episodes of sickle cell
it produces more fetal hemoglobin (HbF)
HbF will replace the bad sickle cells

82
Q

HbC what mutation

A

Glu to Lys

83
Q

HbC disease

A

hemoglobin C disease

84
Q

what hapens in HbC disease

A

hemoglobin crystalizes

the RBC don’t work

85
Q

glu to lys is what disease

A

HbC disease

86
Q

Why can CO kill you

A

it has MUCH higher affinity for Hb than O2

87
Q

if you bind CO to Fe in Hb it causes what

A

a shift to the relaxed state - prevents release of O2 in tissues

88
Q

when CO binds to Fe what does it do regarding relaxed state

A

prevents release of O2 to tissues

89
Q

if one subunit is boudn to CO what happens to the rest of the subunits

A

they can no longer work

90
Q

Fe has to be in what state to work

A

reduced

91
Q

reduction of Fe3+ catalysed by what

A

Methaemoglobinemin reductase

92
Q

what is another anme for Methaemoglobinemin reductase

A

NADH-cytochrome b5 reductase

93
Q

congenital affects in hemoglobin making you prone to having oxidation of iron is what disease

A

Methaemoglobinemia

94
Q

what are the two types of methmoglobin reductase

A

Type I and Type II

95
Q

describe type I Methemoglobin reductase deficiency

A

soluble form of enzyme, only affects RBC, mild methamemoglibnaema

96
Q

describe type II Methemoglobin reductase deficiency

A

soluble & microsomal form, all tissues including CNS

97
Q

what is treatment for cyanide poisoning

A

change from normal hemoglobin to methemoglobin

98
Q

why do you use methemogloibin to treat cyanide poisoning

A

using oxidized version of hemoglobin to trap cyanide

99
Q

HbA1c is what

A

hemoglobin produced by glucose reaction

100
Q

RBC use what to obtain energy

A

glucose

101
Q

how can HbA1c be used to measure diabetes

A

there is a lot of glucose in blood to provide energy - the reaction will produce HbA1c so you can use it to measure the glucose levels in blood

102
Q

what happens once there are HbA1c

A

have to wait for the RBC to die - once it is bound to RBC it stays bound

103
Q

the carbamino effect is one method of doing what

A

transporting CO2 in blood

104
Q

when there is high O2 in lungs, what does hb do?

A

binds O2 and releases CO2

105
Q

most CO2 is carried how

A

HCO3-

106
Q

draw out how most CO2 is carried in the blood as carbamino-terminal residue

A

pg 19

107
Q

2,3 BPG is synthesized from what

A

intermediate of glycolysis

108
Q

what does 2,3 BPG bind

A

deoxyhemoglobin

109
Q

when 2,3 BPG binds deoxyhemoglobin what does it do

A

increases the energy required for conformational change

stabilises tense state

110
Q

Hb-O2 + 2,3-BPG

A

Hb-2,3-BPG + O2

111
Q

how does Cl- inhibit O2

A

binds neutralizing electrostatic charges

stabilizes T state

MCB II Block 2 (10 decks)

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