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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
low affinity state of hemoglobin is called
t state
26
t state stands for
tense state
27
does t state ever happen
not in reality, its just in theory
28
what happens in t state
low oxygen affinity
29
binding of oxygen to one subunit in heme does what
increases affinity of the other, so oxygen can more easily bind another heme group
30
what does r state stand for
relaxed state
31
cooperativity of oxygen binding derives from
conformational changes in tertiary structure of each globin chain
32
conformational change from t state makes it become
r state with higher afinity
33
binding of 1st oxygen has what rate
its low - b/c energy needed to make first adjustment in conformation
34
what is the state with low affinity for o2
t state
35
what is the state with high affinity for o2
r state
36
describe properties of t state
Low oxygen affinity Resists the binding of oxygen Deoxygenated More salt bridges
37
describe properites of r state
High oxygen affinity Binding of oxygen is facilitated Oxygenated Fewer salt bridges
38
describe the middle of hemoglobin in structure of t and r state
the middle of t state looks more open the middle of r state looks more close
39
what are the three ways hemoglobin binding for oygen is decreased
1. - low pH (Bohr effect) 2. - binding of 2,3 bisphosphoglycerate 3. - covalent attachment of carbon dioxide (CO2)
40
Co2 gets hydrated and produces
carbolic acid
41
carbolic acid produces
more hydrogen and lowers ph
42
what does co2 do in regards to ph
it lower ph
43
how does co2 affect oxygen
it lowers ph which decreases binding for oxygen
44
2,3 bisphosphoglycerate - what is it
conjugate base
45
if ph is increased what happens to affinity for oxygen
it increases
46
what is ph of blood in lungs
7.6
47
what is ph of blood in tissues
7.2
48
if ph is decreased what happens to affinity for oxgyen
it decreases
49
what is bohr effect
describing how ph affects affinity for oxygen
50
one waste product of tissues is
co2
51
draw reaction of CO2 with water
CO2 + H2O ↔ HCO3− + H+
52
carbonic anyhydrase does what
decreases ph of cell
53
what does H+ do to hemoglobin
it binds to hemoglobin and stabilizes the T state
54
how does hemoglobin act as buffer
H+ can bind to it
55
draw out bohr affect, list all the steps
pg 15
56
histidine does what
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
2,3-bisphosphoglycerate is an acid or base
acid
58
what form is 2,3-bisphosphoglycerate present in body
conjugate base
59
what produces 2,3-bisphosphoglycerate
RBC
60
when hemoglobin is in T state what fits perfectly
2,3-bisphosphoglycerate
61
when t state is what kind of charge
positive charges
62
look at structure of 2,3-bisphosphoglycerate and think about the negative charges and how it binds to t state
pg 17
63
at sea level what is level of saturation of hemoglobin in lungs
100%
64
when at high altitude what happens to oxygen saturation in lungs
pressure of oxygen in lungs is lower | oxygen levels decreased, so there is less release of oxygen
65
how much oxygen is released at sea level
38%
66
what does body do to compensate at high altitude
body produces more BPG
67
what does BPG stand for
2,3-bisphosphoglycerate
68
if body produces more BPG what does it do to oxygen
releases more oxygen
69
anemia compensaes by producing more
2,3 BPG
70
when mutation in pyruvae kinase have high levels of
2,3 BPG
71
in fetus produce what hemoglobin
hemoglobin F
72
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.
increases oxygen in tissues
73
fetal hemoglobin having less affinity for 2,3, BPG has higher affinity for
oxygen
74
mother vs baby oxygen
mother has lower affinity for oxygen than baby so oxygen can migrate to baby
75
sickle cell anemia is due to mutation in
hemoglobin
76
sickle cell anemia provides protection against
malaria
77
what is mutation in sickle cell
Glu6 → Val in the beta chain of Hb
78
when glutamic acid is changed to valine in hemoglobin what happen
the hemoglobin has hydrophobic bump
79
hemoglobin with the bump interacts with other peplomers and form a polymer and this does what
can clump capillaries, the blood cell is sickled shape
80
what is common treatment for sickle cell anemia
hydorxyurea
81
what does hydroxyurea do
prevents or makes less frequent the episodes of sickle cell it produces more fetal hemoglobin (HbF) HbF will replace the bad sickle cells
82
HbC what mutation
Glu to Lys
83
HbC disease
hemoglobin C disease
84
what hapens in HbC disease
hemoglobin crystalizes | the RBC don't work
85
glu to lys is what disease
HbC disease
86
Why can CO kill you
it has MUCH higher affinity for Hb than O2
87
if you bind CO to Fe in Hb it causes what
a shift to the relaxed state - prevents release of O2 in tissues
88
when CO binds to Fe what does it do regarding relaxed state
prevents release of O2 to tissues
89
if one subunit is boudn to CO what happens to the rest of the subunits
they can no longer work
90
Fe has to be in what state to work
reduced
91
reduction of Fe3+ catalysed by what
Methaemoglobinemin reductase
92
what is another anme for Methaemoglobinemin reductase
NADH-cytochrome b5 reductase
93
congenital affects in hemoglobin making you prone to having oxidation of iron is what disease
Methaemoglobinemia
94
what are the two types of methmoglobin reductase
Type I and Type II
95
describe type I Methemoglobin reductase deficiency
soluble form of enzyme, only affects RBC, mild methamemoglibnaema
96
describe type II Methemoglobin reductase deficiency
soluble & microsomal form, all tissues including CNS
97
what is treatment for cyanide poisoning
change from normal hemoglobin to methemoglobin
98
why do you use methemogloibin to treat cyanide poisoning
using oxidized version of hemoglobin to trap cyanide
99
HbA1c is what
hemoglobin produced by glucose reaction
100
RBC use what to obtain energy
glucose
101
how can HbA1c be used to measure diabetes
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
what happens once there are HbA1c
have to wait for the RBC to die - once it is bound to RBC it stays bound
103
the carbamino effect is one method of doing what
transporting CO2 in blood
104
when there is high O2 in lungs, what does hb do?
binds O2 and releases CO2
105
most CO2 is carried how
HCO3-
106
draw out how most CO2 is carried in the blood as carbamino-terminal residue
pg 19
107
2,3 BPG is synthesized from what
intermediate of glycolysis
108
what does 2,3 BPG bind
deoxyhemoglobin
109
when 2,3 BPG binds deoxyhemoglobin what does it do
increases the energy required for conformational change | stabilises tense state
110
Hb-O2 + 2,3-BPG
Hb-2,3-BPG + O2
111
how does Cl- inhibit O2
binds neutralizing electrostatic charges | stabilizes T state

MCB II Block 2 (10 decks)

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