Larger animals needed so much oxygen that many hemes in the blood would make the blood thick and syrupy; it wouldn't flow at all easily through the body to where the oxygen is needed. So the hemes were placed in a protein basket that carried the oxygen to where it was needed. The protein basket (around the heme) delivers oxygen by changing its shape. The complete structure is known as hemoglobin.
Let's think what proteins might add to a heme for control, so that a heme might deliver just the right amount of needed oxygen to an area of the body.
When oxygen is inserted, the molecule changes to hold it securely. This made the great chemist Roald Hoffman think of the way a puck settles into the glove of a great hockey goalie. When hemoglobin reaches an area where the concentration of oxygen is low, it changes its shape and the heme is released.
As we know, small changes make big differences. Carbon monoxide fits into that basket space too. Cyanide works by changing the heme structure so it cannot carry oxygen. An alteration of only ONE amino acid in the protein strand causes Sickle Cell Anemia. This disease lowers the amount of oxygen that can be carried, and slows bloods passage.Return to Hemoglobin.
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