Myoglobin and Hemoglobin

Question 1

What structure is more conserved ?

Answer 1

tertiary

Question 2

Out of myoglobin and hemoglobin, which is a monomer and which is a heterotetramer?

Answer 2

• monomer -> myoglobin
• heterotetraglobin -> hemoglobin

Question 3

What is the structure of heme?

Answer 3

• 4 rings= tetrapyrrole
• Fe interacts with nitrogens in the middle and binds to proximal His

Question 4

What are the exceptions in the structure of heme?

Answer 4

proximal & distal histidines

Question 5

What enhances O2 delivery by hemoglobin?

Answer 5

cooperativity

Question 6

What determines a tight or relaxed conformation?

Answer 6

• tight= no O2 bound= right shift = deoxyhemoglobin
• relaxed= O2 bound= left shift= oxyhemoglobin

Question 7

What causes a conformational chgange in hemoglobin from the T state to R state?

Answer 7

when O2 binds to the Fe of hemoglobin

Question 8

What is indicative of cooperation?

Answer 8

when binding displays sigmoidal behavior

Question 9

Cooperative binding helps hemoglobin deliver how much more O2?

Answer 9

2x as much

Question 10

Is myoglobin or hemoglobin a better grabber of O2 under partial pressures?

Answer 10

myoglobin

Question 11

When do O2 and histidine get pulled?

Answer 11

when O2 binds to iron

Question 12

What is the function of myoglobin?

Answer 12

O2 transport in muscles

Question 13

What are the axis of the oxygen saturation curve of myoglobin?

Answer 13

• x-axis: Y
• y-axis: pO2 in torr

Question 14

What is the relationship between partial pressure of O2 and myoglobin?

Answer 14

when pO2 increases -> myoglobin saturation increases

Question 15

What type of curve do myoglobin and hemoglobin have?

Answer 15

• myoglobin: hyperbolic
• hemoglobin: sigmoidal

Question 16

At pO2 of 100 in the lungs what is the percentage of hemoglobin sites are saturated with O2?

Answer 16

98%

Question 17

At pO2 of 24 in the tissues what is the percentage of hemoglobin sites are saturated with O2?

Answer 17

32%

Question 18

What are the different meanings of the Hill coefficient?

Answer 18

• nH = 1 -> noncooperativity
• nH < 1-> negative cooperativity
• nH > 1 -> positive cooperativity

Question 19

What is isohydric transport in the Bohr effect?

Answer 19

CO2 produced by cells are transported to the lung in plasma as a bicarbonate

Question 20

What is carbamino transport in the Bohr effect?

Answer 20

CO2 produced by cells is transported to the lung by nonenzymatic reaction of CO2 to NH2 terminal group

Question 21

What happens when protons and CO2 shift the curve to the right?

Answer 21

• stabilization of T state
• weaker O2 binding

Question 22

What increases 2,3,BPG in red blood cells and what lowers it?

Answer 22

• hypoxia -> increases
• hyperoxia -> lowers

Question 23

2,3 BPG causes what shift in the hemoglobin graph?

Answer 23

right shift

Question 24

What is a disease associated with hemoglobin?

Answer 24

thalassemia syndrome

Question 25

Is 2,3 BPG a positive or negative effector of O2?

Answer 25

negative

Question 26

What amino acids are involved in the binding of a proton to hemoglobin?

Answer 26

His & Asp