| Thus, when deoxyhemoglobin takes up oxygen, its affinity for more oxygen increases, and vice versa. |
| These two wavelengths are chosen because the difference of the absorption of oxyhemoglobin and deoxyhemoglobin is greatest at these points. |
| When deoxyhemoglobin picks up an oxygen molecule, this histidine residue moves away and returns once the oxygen is securely attached to form a hydrogen bond with it. |
