BIOC 384 EXAM 2 EXAM
What is the structure of hemoglobin?
Hemoglobin is a tetrameric protein with four subunits
(two alpha, two beta), each containing its own heme
group.
What is myoglobin and its primary function?
Myoglobin is concentrated in muscle tissue and
functions as oxygen storage.
What is the heme group in myoglobin and hemoglobin?
It is a Fe2+ porphyrin complex that binds O2 reversibly.
What is the role of proximal and distal histidine in the
heme group?
, Proximal histidine connects with Fe2+ to the polypeptide
chain, while distal histidine forms a hydrogen bond with
O2.
What is the significance of the Fe2+ coordination bonds
in the heme group?
Fe2+ has six coordination bonds, four with nitrogens in
the plane and two above and below the ring with
histidines.
What happens to Fe2+ in the absence of O2?
Fe2+ is not in the plane of the porphyrin ring.
What occurs when O2 binds to heme?
The shared electrons make the radius of Fe2+ smaller,
allowing it to move into the plane of the ring, which pulls
the proximal histidine and F helix, relaxing it into the R
state.
How much does His F8 displace upon O2 binding?
His F8 has a displacement of 0.6 Angstroms.
What is the effect of carbon monoxide on heme in
myoglobin and hemoglobin?
What is the structure of hemoglobin?
Hemoglobin is a tetrameric protein with four subunits
(two alpha, two beta), each containing its own heme
group.
What is myoglobin and its primary function?
Myoglobin is concentrated in muscle tissue and
functions as oxygen storage.
What is the heme group in myoglobin and hemoglobin?
It is a Fe2+ porphyrin complex that binds O2 reversibly.
What is the role of proximal and distal histidine in the
heme group?
, Proximal histidine connects with Fe2+ to the polypeptide
chain, while distal histidine forms a hydrogen bond with
O2.
What is the significance of the Fe2+ coordination bonds
in the heme group?
Fe2+ has six coordination bonds, four with nitrogens in
the plane and two above and below the ring with
histidines.
What happens to Fe2+ in the absence of O2?
Fe2+ is not in the plane of the porphyrin ring.
What occurs when O2 binds to heme?
The shared electrons make the radius of Fe2+ smaller,
allowing it to move into the plane of the ring, which pulls
the proximal histidine and F helix, relaxing it into the R
state.
How much does His F8 displace upon O2 binding?
His F8 has a displacement of 0.6 Angstroms.
What is the effect of carbon monoxide on heme in
myoglobin and hemoglobin?
