Fetal Hemoglobin(hereinafter reffered to as "hemoglobinF").
Fetus is well supplied with oxygen molecules in mother's belly.
Fetus has a certain kind of hemoglobin for fetus, and it's called hemoglobinF (hereinafter reffered to as "(3)deoxyhemoglobinF", in addition, the material whichi is coordinated by oxygen molecule to deoxyhemoglobin reffered to as "(1)oxyhemoglobinF").
Mother has a certain kind of hemoglobin for adult, and it's called Adult hemoglobin or hemoglibinA (hereinafter reffered to as "(4)deoxyhemoglobinA", in addition, the material whichi is coordinated by oxygen molecule to (4)deoxyhemoglobinA reffered to as "(2)oxyhemoglobiA").
In mother's placenta, the energy's decrease in changing (3)deoxihomoglobinF into (1)oxihomoglobinF surpasses the energy's increase in changing (2)oxihomoglobinA into (4)deoxihomoglobinA.
In general, it becomes a stable state with low energy.
Due to that (3)deoxyhemoglobinF has greater affinity for oxygen atom than (4)deoxhemoglobinA under normal conditions, oxygen atom is well suppulied from mother to fetus.
In addition, including the transfer of protons and carbon dioxide, it goes from an unstable state with high energy to a state with low energy.
When an oxygen molecule coordinates to ferrous ions as the sixth ligand, the oxygen molecule is an electron attractive group.
As a result (1)oxyhemoglobinF becomes stronger as acids than (3)deoxyhemoglobinF and (2)oxyhemoglobinA becomes stronger as acids than (4)deoxyhemoglobinA.
And although they are all weak acids, their strength as acids are the followings in order of strength.
(1)oxyhemoglobinF
(2)oxyhemoglobinA
(3)deoxyhemoglobinF
(4)deoxyhemoglobinA
Combined the order of strength of these acids and the fluctuation of pH value of the blood well, oxygen molecules are delivered to fetus.
