Hemoglobin, Myoglobin, Heme

Question 1

What are the specialized globular heme proteins that have a capacity to bind Oxygen?

Answer 1

Hemoglobins and myoglobin

Question 2

Define heme

Answer 2

Organic cofactors bound to iron with a heterocyclic porfyrin ring

Question 3

Hemoglobin

Answer 3

A protein requires for transportation of oxygen which fuels metabolism.
It is a tetramer with 2 types of subunits.

Question 4

What is Myoglobin

Answer 4

A storage reservoir for oxygen in resting muscles. When they contract oxygen is released.
It is a monomer

Question 5

What is the structure of Hemoglobin?

Answer 5

A quaternary structure composed of 2 alpha and beta dimers.

The confirmation of hemoglobin is altered upon binding oxygen.

Question 6

What happens to hemoglobin at low concentrations of oxygen?

Answer 6

At low concentrations of oxygen Hemoglobin takes on a T-State and does not bind O2.

Deoxyhemoglobin

Question 7

What happens to concentrations of hemoglobin at high oxygen concentrations?

Answer 7

At high oxygen concentrations oxygen bonds to one O2 and is converted into the R-state.

Oxyhemoglobin

Question 8

Explain cooperative binding

Answer 8

With each O2 binding even cooperated with the next resulting in increased affinity for the next oxygen.

Question 9

What is the relationship between hemoglobin and Oxogen.

Answer 9

Hemoglobin is an allosteric protein
Oxygen is it’s homotrophic effector.

Oxygen Causes conversion between oxy and deoxyhemoglobin

Question 10

Define P50

Answer 10

P50 is the partial pressure of Oxygen at which a molecule is 50% saturated with Oxygen

The lower the P50 the higher the affinity for oxygen.

Question 11

What is the P50 of myoglobin?

Answer 11

Myoglobin has a P50 of 1.

When graph the saturation omg oxygen for myoglobin the curve is hyperbolic meaning it’s either bound or unbound.

Myoglobin releases O2 in response to low oxygen levels.

Question 12

What is the P50 of hemoglobin?

Answer 12

Hemoglobin has a P50 of 26

When graph the saturation omg oxygen for myoglobin the curve is sigmoidal.

Due to allosteric and cooperative binding.

Question 13

What are the negative allosteric effectors of Hemoglobin?

Answer 13

The citric acid cycle and glycolysis pathway.

Citric Acid Cycle produces Oxygen

Glycolysis produces 2 3 BPG

Negative effector shift the curve to the right for hemoglobin

Question 14

What are the negative Heterotrophic Effectors of Hemoglobin?

Answer 14

pH

Low pH = Low affinity for Oxygen

High pH = High affinity for Oxygen

Question 15

What are the positive heterotrophic effectors of Hemoglobin

Answer 15

Carbon Monoxide

It binds with a higher affinity and favors R-State conformation

Question 16

What is major Hemoglobin

Answer 16

Hemoglobin A
90% of adult hemoglobin

Composed of alpha 2 and beta 2 ( a comes before b)

Question 17

What is minor hemoglobin

Answer 17

Fetal Hemoglobin
HBF
60% HBF at birth
2 alpha subunits and 2 gamma subunits

Question 18

What is the mutation of Hemoglobin in Sickle Cell Disease. HbS

Answer 18

Single point mutation on the beta globin gene.
Glutamic Acid is substituted with a non polar hydrophobic valine
Glu6Val.

Question 19

How does sickle cell cause anemia ?

Answer 19

Anemia - abnormally low hemoglobin concentration in whole blood.

Sickle cell produces anemia because sickled cells are marked for destruction and last less than 20 days.

Question 20

What is thalassemia?

Answer 20

When mutation in DNA results in loss of alpha or beta subunits.

A- thalessemia A helix subunits in low supply
B- thalessemia B chain subunits in low supply