oxygen is attached to the iron ion on a hemoglobin molecule.
oxygen is attached to the iron ion on a hemoglobin molecule.
where is oxygen attached on a hemoglobin molecule?
the iron ion
the blood's red color is due to the spectral properties of the hemic iron ions in hemoglobin. each human red blood cell contains approximately 270 million of these hemoglobin molecules. each hemoglobin molecule carries four heme groups; hemoglobin constitutes about a third of the total cell volume. hemoglobin is responsible for the transport of more than 98% of the oxygen in the body (the remaining oxygen is carried dissolved in the blood plasma). the red blood cells of an average adult human male store collectively about 2.5 grams of iron, representing about 65% of the total iron contained in the body.
red blood cell
an example of positive cooperativity is the binding of oxygen to hemoglobin. one oxygen molecule can bind to the ferrous iron of a heme molecule in each of the four chains of a hemoglobin molecule. deoxy-hemoglobin has a relatively low affinity for oxygen, but when one molecule binds to a single heme, the oxygen affinity increases, allowing the second molecule to bind more easily, and the third and fourth even more easily. the oxygen affinity of 3-oxy-hemoglobin is ~300 times greater than that of deoxy-hemoglobin. this behavior leads the affinity curve of hemoglobin to be sigmoidal, rather than hyperbolic as with the monomeric myoglobin. by the same process, the ability for hemoglobin to lose oxygen increases as fewer oxygen molecules are bound. "see also oxygen-hemoglobin dissociation curve.
cooperativity