B4.024 - Myoglobin and Hemoglobin

Question 1

biological role of Mb

Answer 1

stores O2 in muscle

Question 2

biological role of Hb

Answer 2

red blood cells, transports O2 from lungs to tissues

Question 3

what is the % of similarity between Hb and Mg

Answer 3

38%

Question 4

quaternary structure of Hb and Mg

Answer 4

Hb - tetramer (alpha 2, X2) Mg - monomer

Question 5

what form of Hb can assemble but doesnt function

Answer 5

B4

Question 6

free heme binds what more tightly than O2

Answer 6

CO

Question 7

what hinders CO binding

Answer 7

protein

Question 8

what role does protein have in heme prosthetic groups

Answer 8

hinders CO binding Inhibits oxidation of iron

Question 9

describe the color change of hemoglobin

Answer 9

when bound to oxygen it has a red color when not bound to oxygen it has a blue color

Question 10

describe the curve of oxygen binding to Hb

Answer 10

its sigmoidal because of cooperative binding

Question 11

how many binding events does Hb have

Answer 11

4 - 4 binding sites

Question 12

what does a Mg binding curve look like

Answer 12

simple hyperbolic

Question 13

which binds more tightly to oxygen Hb or Mg and why

Answer 13

Mg because you need to steal it away to give to muscle

Question 14

what causes cooperative binding

Answer 14

conformational change with oxygen binding offers higher affinity

Question 15

where does BPG come from

Answer 15

synthesized in erythrocytes from glucose

Question 16

what does BPG do with Hb

Answer 16

can bind to Hb (has many binding sites)

Question 17

describe BPG charge

Answer 17

its very negatively charged allowing it to bind to positively charged AAs

Question 18

what does BPG do with Hb

Answer 18

binds to low affinity form drives reaction back to deoxy form of Hb

Question 19

what would the Hb binding curve look like without BPG

Answer 19

the Mg curve

Question 20

when is BPG upregulated and lost

Answer 20

up-regulated with hypoxia lost during blood storage (contributes to shelf life) because its used up for energy

Question 21

how is BPG binding different in fetal Hb

Answer 21

not as high of an affinity for binding, because of higher need for taking oxygen from moms blood

Question 22

what does H+ do with Hb

Answer 22

weakens oxygen binding

Question 23

what does CO2 do with Hb

Answer 23

allosteric inhibitor of O2 affinity

Question 24

describe binding of CO2

Answer 24

covalent and reversible binding at N terminal amines

Question 25

what do Mb and Hb moonlight as

Answer 25

enzymes changing NO to NO3 this disables heme so it cant bind oxygen

Question 26

describe the color change in blood due to NO3 binding to heme and blocking oxygen binding

Answer 26

it turns chocolate brown

Question 27

how does altitude affect Hb binding

Answer 27

higher altitude has less oxygen concentration oxygen in body will diffuse back out

Question 28

what does the presence of Fe3+ mean for the Hb binding curve

Answer 28

never can get fraction binding all the way to one so the curve is lower

Question 29

antidote to drugs that oxidize Fe2+?

Answer 29

methylene blue

Question 30

describe symptoms of CO poisoning at \<10% \>10%, 20%, 25%, 30% COHb level

Answer 30

\<10% - headache dizziness \>10% - slight headache 20% - slight headache, loss of judgment 25% - frontal headache 30% - dizziness, nausea, convulsions

Question 31

why is CO poisoning so toxic

Answer 31

binds any protein with heme binds at extremely low [CO] substoichiometric conditions it still has effect

Question 32

what does it mean that CO has effects at substoichiometric conditions

Answer 32

only one bound CO causes an effect, dont need 4

Question 33

what does CO do to heme

Answer 33

precules O2 binding to this site enhances O2 binding at other sites

Question 34

what does the CO Hb binding curve look like

Answer 34

like Mb but lower bc it cant bind as much O2 but cant release what it has

Question 35

what is thalassemia

Answer 35

loss of one subunit stoichiometry gets messed up can aggregate and precipitate causes anemia

Question 36

what are hemoglobinopathies

Answer 36

sickle cell point mutation affecting Hb

Question 37

what does Hb scavenge

Answer 37

NO, causes spike in BP

Question 38

if any NO makes it too far what happens

Answer 38

Mg sequesters it to block it from messing with ETC

Question 39

what mops up NO

Answer 39

Free Hb

Question 40

what are things people are trying to make synthesized Hb

Answer 40

Covalently cross link tetramer copy Hb of ocean mammals increase size to avoid NO zone

Question 41

what type of secondary structure is this and how many domains

Answer 41

alpha helix, random coil 1 domain

Question 42

why AAs would you expect on the interior of this and on the surface

Answer 42

hydrophobic - interior hydrophilic - exterior

Question 43

A. Green positions B. Yellow positions C. white positions D. positions with a dash

Answer 43

C - white positions

Question 44

what happens to Hb curve as pH decreases? The O2 affinity higher or lower? Midpoint of new curve higher or lower for pO2? How does this make sense?

Answer 44

Question 45

what happens to the Hb cureve with Hb Kansas?

Answer 45

Question 46

Answer 46