Embedded Files
Notes:
Allosteric regulation is the regulation of a protein via another molecule binding to a site different than the active site.
The term deoxyhemoglobin refers to hemoglobin when O2 is not bound. Oxyhemoglobin is used when O2 is bound. Keeping this in mind, the conformational change that occurs following O2 binding to hemoglobin affects the other subunits in the hemoglobin tetramer. The deoxyhemoglobin is considered to be in the T-state (or tense state) when causes a shift to the R-state (or relaxes state) when bound to oxygen.
The T-state is when the iron molecule is slightly below the plane. Here, it is harder for O2 to have access to it in order to bind. Therefore, when it is in the R-state the iron molecule is moved into the ring plane, causing proximal units to shift. Once this happens for the first time, all of the sites transition to the R-state and have a higher affinity for O2.
Binding Curve:
As you can see, the binding curves for myoglobin and hemoglobin are different! This is due to the fact that myoglobin only has one affinity state, so it shoots up in a hyperbolic curve. Conversely, hemoglobin has different affinity states depending on if the first subunit is bound, giving it a sigmoidal curve Once that first subunit binds, it will have a much easier time binding.
P50: This is when 1/2 of the O2 available is bonded.
Myoglobin has a lower p50 which indicates it having a higher affinity.
Page updated
Google Sites
Report abuse