11 - Hemoglobin Structure and Function Flashcards
What is the most common biological function of globular proteins?
The precise binding of ligands
What is the prosthetic group on myoglobin and hemoglobin called and what does it do?
The heme group, for the reversible binding of oxygen
What is the general structure of the heme group in hemoglobin and myoglobin
A central iron (Fe) loosely bonded to 4 nitrogens
Where is myoglobin mostly found?
Cardiac and skeletal muscle
What is the protein component of myoglobin called?
Globin
What is the structure of the single protein globin?
A single protein with eight α-helices
What are the two structural components of myoglobin?
A heme group enclosed by the eight α-helices of a globin protein
Where is hemoglobin found?
Red blood cells
Which two amino acids are attached to the heme group of hemoglobin? What are their proximities? What does this accomplish?
A distal and proximal histidine are bound to the heme group in hemoglobin. By making a folded globin chain, an oxygen-binding site (composed of heme and two histidines) is made.
What is the primary function of hemoglobin
To transport oxygen from the lungs to tissues
What are the four subunits of hemoglobin?
α1
α2
β1
β2
Each subunit contains a heme group that binds reversibly with oxygen
It can be said that there are 2 identical dimers in hemoglobin composed of four chains. What are the subunits involved in each dimer?
α1β1 α2β2
What is a HbA molecule and what is it composed of?
Two α-chains and two β-chains, each chain being 1 subunit of 4 in hemoglobin.
What is the HbA2 molecule and what is it composed of? How much of it is found in adult humans?
The HbA2 molecule is another type of hemoglobin that contains δ-chains instead of β-chains. About 2% of adult hemoglobin is HbA2 hemoglobin
How is embryonic and fetal hemoglobin different from adult hemoglobin? What is the result of this?
It has ε-chains and γ-chains rather than alpha and beta chains. ε and γ chains have a higher affinity for oxygen gas.