Hemoglobin and Myoglobin Flashcards
Myoglobin is a ________ in _______. It stores _________ in _______ and delivers ___ to _______.
Binds ______ at ______ levels.
oxygen carrier in muscle cells
O2 in muscle cells, delivers it to mitochondria
O2 at low levels
Hemoglobin is a _________ in _____. It binds ______ in ________ and release _______ in the _______.
It is sensitive to small changes in ______ allowing for ______. It also carries ________ from the ________ to the ____.
oxygen carrier in blood
O2 in the lungs
O2 to the tissues
Oxygen allowing for maintenance of homeostasis
CO2 from the tissues to the lungs.
RBC’s in lungs have high levels of O2 this favoring binding to _____. Lower _____ in RBC’s in muscles triggers the _________ of _______ from ____. In muscle, ____ will take up _____.
Hb, O2 levels
release of O2 from Hb. Mb, O2
The _____ can oxidize fuel during the ______. They consume ______ and release _______. When CO2 is release into the blood is is transported as ____ or ____.
CO2 is released by the _____.
mitochondria, ETC
O2, CO2
HCO3 or Hb-CO2.
Lungs
Myoglobin has a _____ protein structure while hemoglobin has a _______.
Myoglobin has a___ group while hemoglobin has ______ because it is made up of ______ each with _______..
tertiary, quaternary
1, 4
4 polypeptide chains, 1 heme group
Heme is an ____ of ______ and ___ where _____ binds.
It contains a ___ with a single __ that can form ________.
4 bonds have _________. With the other two having ________ and _______ respectively.
active site, Mb and Hb, O2
porphyrin ring, Fe , 6 coordinate bonds
pyrrole nitrogens in the poryphryin ring plane
imidazole nitrogen from a histidine in polypeptide chain
ligand (O2 or CO2)
Imagine a rectangle representing the porphyrin ring. 4 bonds extends from the Fe towards the “corners” of the rectangle. The imidazole nitrogen with histidine is protruding from the top while the ligand is protruding from the bottom.
O2 binds to _______ in Mb and Hb. Fe__ does NOT bind to ______.
Fe2+ (reduced).
Fe3+ (methemoglobin HbMet)
Mb has a _____ affinity for _____. It will release very little O2 between ____ and ________.
O2, 10 and 100mmHg
Hb has a _____ affinity for ________. It has __________ and a _____ shape on a linear plot.
low, O2
positive cooperativity, sigmoid curve
Features of Positive Cooperativity
- 2 ligand binding site
- 2 receptor conformations with different affinities for ligand
- First ligand bound has lower affinity (larger Kd) than subsequent Ligands.
- The hill slope is more than 1 and less than the number of sites.
- Occupancy is more sensitive to changes in ligand concentration.
There are 2 conformations of Hb. _____ and ___.
Describe them.
T or Taut has low affinity for O2 and is prevalent at low O2 in tissues.
R or Relaxed has a high affinity for o2 and is prevalent at high O2 in lungs.
Hb is made of a/b dimers with dimers being in varying states
When O2 is unavailable, Fe is ______ of ______ and Hb is stabilized in the _______.
When O2 binds, the Fe is ______ into the _______ which stabilizes the ________. This increases _____________.
out , the heme plate, T-conformation
pulled into the heme plate, conformation, affinity for O2 at other sites.
Mb-O2 binding is ______.
Hill Coefficient:
Response in changes to O2:
Hb-O2 binding is ______.
Hill Coefficient:
Changes in response to O2:
non-cooperative
=1
Low response to changes in O2
positive cooperativity
>1
Sigmoid Curve
Very responsive to changes in O2
O2 is an _________ of Hb because it _____________ and increases ___________.
homotropic allosteric modifier
binds to the active site, increases O2 affinity at other active sites
Heterotropic inhibitors _________________ while activators __________.
stabilize the low affinity or T-state
stabilize the high affinity or R-state.
