Oxygen Transporters

Question 1

myoglobin

Answer 1

serves as an oxygen transporter in muscles

Question 2

prosthetic group

Answer 2

firmly attaches to a protein, not removed during protein purification (example: heme)

Question 3

oxidation vs. oxygenation

Answer 3

oxygenation = adding oxygen molecule to heme, oxidation = converting from Fe2+ to Fe3+

Question 4

metmyoglobin

Answer 4

myoglobin which carries a Fe3+

Question 5

proximal histidine

Answer 5

binds to heme, coordinates with iron molecule

Question 6

distal histidine

Answer 6

does not bind to heme, inhibits binding of CO

Question 7

hemoglobin

Answer 7

carries oxygen from lungs to the blood, comprised of four myglobin-like subunits

Question 8

HbA

Answer 8

normal hemoglobin, comprised of two alpha subunits and two beta subunits

Question 9

allosteric protein

Answer 9

meaning “other site” - a protein where molecules can bind to locations other than its active site

Question 10

sigmoidal

Answer 10

shape of the curve associated with oxygen dissociation of hemoglobin

Question 11

The binding an oxygen molecule to hemoglobin will (increase/decrease) the affinity for other oxygen molecules

Answer 11

increase

Question 12

Hill plot

Answer 12

measures the extent of cooperativity

Question 13

Hill coefficient

Answer 13

indicates degree of cooperativity, 1 = no cooperativity (myoglobin), 2 = positive cooperativity (hemoglobin)

Question 14

taut state

Answer 14

when no oxygen is bound to hemoglobin, has a low affinity for oxygen

Question 15

relaxed state

Answer 15

when oxygen is bound to hemoglobin, has a higher affinity for oxygen

Question 16

Bohr effect

Answer 16

the oxygen binding affinity of hemoglobin is affected by CO2 and H+

Question 17

allosteric effectors

Answer 17

molecules that change the binding affinity of different molecules binding to a protein

Question 18

BPG

Answer 18

2,3-bisphosphoglycerate - controls the oxygen of hemoglobin by binding in central cavity between beta subunits

Question 19

BPG binds to hemoglobin primarily through what type of interactions?

Answer 19

electrostatic interactions

Question 20

HbF

Answer 20

fetal hemoglobin, has two alpha subunits and two gamma subunits

Question 21

Gamma subunit of hemoglobin

Answer 21

has a higher affinity for oxygen than beta subunit (has fewer positively charged amino acids, doesnt bind as well to BPG), allows fetus to get oxygen from mother

Question 22

Sickle cell anemia

Answer 22

substitution of valine for glutamate on the exterior of hemoglobin (HbS), symptoms display after birth, polymers form resulting in sickling and lysis of red blood cells

Question 23

Methemoglobinemia

Answer 23

disease in which hemoglobin carries an Fe3+ charge, can only be heterozygous, can be acquired from oxidizing chemicals like nitrates

Question 24

Thalassemias

Answer 24

imbalance of either alpha or beta subunit production of hemoglobin