Hemoglobin by molecules such as carbon monoxide (for example, from tobacco smoking, exhaust gas, and incomplete combustion in furnaces). CO competes with oxygen at the heme binding site. Hemoglobin's binding affinity for CO is 250 times greater than its affinity for oxygen, meaning that small amounts of CO dramatically reduce hemoglobin's ability to transport oxygen. Since carbon monoxide is a colorless, odorless and tasteless gas, and poses a potentially fatal threat, carbon monoxide detectors have become commercially available to warn of dangerous levels in residences. When hemoglobin combines with CO, it forms a very bright red compound called carboxyhemoglobin, which may
Embryonic hemoglobin two beta chains. It is quite unstable, more so than even hemoglobin Gower 1, and breaks down very rapidly under stress. Despite this, it has been proposed as a candidate for reactivation in cases of severe α thalassemia or hemoglobinopathies afflicting the alpha chain. Embryonic hemoglobin The human embryonic haemoglobins were discovered in 1961. These were Hb-Gower 1, consisting of 2 zeta chains and 2 epsilon chains, and Hb-Gower 2, which consists of 2 αlpha-chains and 2 epsilon-chains, the zeta and epsilon chains being the embryonic haemoglobin chains. Embryonic hemoglobin is a tetramer produced in the blood islands in the