Biochemistry Exam 1 Lecture 4

Front 1

How are aggregates created, and can you get rid of them?

Back 1

They are caused by misfolded proteins and they cannot be refolded or degraded.

Front 2

What diseases are caused by aggregates?

Back 2

Cataracts, prion, alzheimers, parkinsons, and huntingtons.

Front 3

What are prions?

Back 3

A small protein encoded in a normal cell.

Front 4

How can non toxic prions become toxic prions?

Back 4

Rarely a toxic conformation si produced by a mutation or something and it stimulates the conformation change of other molecules to toxic form

Front 5

What does the toxic form look like?

Back 5

Beta sheets which can interact between subunits.

Front 6

What is the prion that facilitates structural change of the other PrPc?

Back 6

It’s called PrPsc.

Front 7

What causes alzheimers?

Back 7

The amyloid beta fibril, beta stacking causes an aggregate to form, which will cause large filament in patients brain.

Front 8

What are types of proteins?

Back 8

Coiled coil, leucine zipper, collagen, myoglobin, porin, helix turn helix, GFP

Front 9

What is cool about green fluorescent protein?

Back 9

When it reacts with specific proteins, it has a sponteanous reaction (cyclization, dehydration, and oxidation) which will cause the fluorescence to appear. It’s super useful, and comes from jellyfish

Front 10

What is hemoglobin a good example of?

Back 10

Molecular interaction, allosteric regulation, and cooperative interactions.

Front 11

Is hemoglobin an enzyme?

Back 11

No

Front 12

What provides the binding site for oxygen?

Back 12

Iron

Front 13

Where does hemoglobin bind O2?

Back 13

Lungs

Front 14

Where does hemoglobin release o2?

Back 14

Tissue

Front 15

Where does myoglobin exist primarily?

Back 15

Muscle

Front 16

Do you find myoglobin in the bloodstream?

Back 16

No.

Front 17

What is the disassociation constant for myoglobin?

Back 17

K=[O2][Myo]/[Myo-O2]

Front 18

What does it mean for Kd to increase?

Back 18

The affinity for oxygen will decrease

Front 19

What is the structure of myoglobin/hemoglobin like?

Back 19

They look very similar to eachother. It is rigid and unchanging, but the confirmation of one alpha helix in the subunit via the histidine.

Front 20

In cooperative binding, what percent of the oxygen is released into the tissue?

Back 20

66%

Front 21

In non-cooperative binding, what percent of the oxygen is released into the tissue?

Back 21

38%

Front 22

Is hemoglobin ever not red?

Back 22

No! It’s always red!

Front 23

As pH decreases in the blood, what happens to the affinity to bind to oxygen?

Back 23

It decreases.

Front 24

How is hemoglobin affected by CO2?

Back 24

CO2 causes carbonic acid to form inside of a red blood cell. This creates a drop in the pH of the cell, so the binding affinity will drop.

Front 25

What kind of binding do you see with hemoglobin?

Back 25

Cooperative

Front 26

How many Hemes are there in a Hb?

Back 26

4 hemes, 4 O2, and 4 binding sites.

Front 27

What is the sequential model?

Back 27

The simple model that assumes that the more hemoglobin binds, the better affinity it has.

Front 28

What is the sequential model in terms of Kd?

Back 28

KD1>KD2>KD3>KD4

Front 29

What is the concerted model?

Back 29

There are two phases for binding, R and T. In this way, the more O2 is bound, the more the R state is favored. The less o2 is bound, the less it is favored, the more the T state is favored.

Front 30

What has more affinity for oxygen, hemoglobin or myoglobin?

Back 30

Myoglobin.

Front 31

Where are H+ and PCO2 high?

Back 31

Tissues

Front 32

What is the benefit of facilitated O2 release?

Back 32

The tissue can receive more O2

Front 33

What is type of control is H+ PCO2 using?

Back 33

Allosteric control

Front 34

Does any blood get exchanged from mother to fetus?

Back 34

No.

Front 35

Does mom and fetus exchange O2?

Back 35

Yes.

Front 36

How does fetal hemoglobin compare to adult hemoglobin?

Back 36

Fetal hemoglobin has a higher affinity to the O2 than the adult.

Front 37

What do more salt bridges favor?

Back 37

T state.

Front 38

What is a salt bridge?

Back 38

The ionic interaction of histidine to anything else.

Front 39

What does histidine form a salt bridge with?

Back 39

Asp- on the alpha helix

Front 40

What subunits do adult hemoglobins have?

Back 40

2alpha and 2 beta.

Front 41

What subunits do fetus hemoglobin have?

Back 41

2 alpha, 2 gamma.

Front 42

What is the older/less likely hypothesis for binding o2?

Back 42

Sequential hypothesis

Front 43

What is the better hypothesis for binding o2?

Back 43

Concerted model

Front 44

What is the assumption for the sequential hypothesis?

Back 44

There is only one value of K1. Then K2. Then K3. Then K4.

Front 45

T state means?

Back 45

Low affinity state

Front 46

R state means?

Back 46

High affinity state.

Front 47

Draw the released state of hemoglobin

Back 47

\/

Front 48

Draw the bound state of hemoglobin

Back 48

/\

Front 49

The conformational change of histidine can affect how many subunits?

Back 49

All

Front 50

What is the bohr affect

Back 50

Oxygen binding of hemoglobin is also regulated by CO2 and pH

Front 51

At low pH what state does the hemoglobin go to?

Back 51

Due to the new saltbridges, it goes to the T state.

Front 52

What stabilizes the T state at high CO2?

Back 52

The carbonated N terminus of beta subunit.

Front 53

Where does the majority of CO2 in blood become?

Back 53

Bicarbonate and dissolved in blood

Front 54

What percent of Co2 is carried by Hb?

Back 54

15%

Front 55

What is the reaction that occurs with CO2 in the blood cell?

Back 55

CO2 and H2O will make H2CO3, which will diassociate

Front 56

What is a pH sensor?

Back 56

Histidine

Front 57

How many subunits are in monomers?

Back 57

1

Front 58

How many subunits are in hemoglobin?

Back 58

4