Haemoglobin and CO

  1. Now here is the question.
    We know that CO is a toxic substance if inhaled, But why ?
    The explaination i heard said that haemoglobin gets attached easier to CO than O2 (note: the subscript option does not seem to work) , Is that right ? And why ?
    I asked that question to my chemics teacher, he said that the mass of 1 mole of CO is less than the mass of 1 mole of O2 , therefore haemoglobin prefers to get attached to CO, but this does not really seem like a scientifical explaination to me (specially with word prefers in the middle).
    Thanks in advance.

    BTW, good nick name Monique :smile:

    Edited for the spelling mistake noted by Jikx
    Last edited: Mar 17, 2003
  2. jcsd
  3. its actually haemoglobin.

    here's a little something i pulled from google.com (mainly because i remember something vaguely about CO having a lower latent energy to combine with haemoglobin than O2, hence is favoured ).

  4. Thanks Jikx.
    But what i really need to know about is this
    I need a chemical explanation for that !
    Anyone ?
  5. It's a big protein, and folds up in a complicated way. There is a particular area where the oxygen/CO/CO2 can "fit" determined by the shape of hemoglobin, its charge distribution, and maybe other stuff. CO happens to fit much better than O2, apparently...

    On an cool side note, your brain actually produces CO (and NO) in small quantities and uses them as a special kind of neurotransmitter!
  6. Hmm.... I would have thought it was something to do with the stability of the CO molecule in comparison to the O2....
    Well, what do I know?! :smile:
  7. Monique

    Monique 4,445
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    Did you realize that it actually makes evolutionary sense that O2 doesn't bind to tightly to haemoglobin?
  8. Can you explain a little bit more please ?
  9. Monique

    Monique 4,445
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    Well, the reason that oxygen doesn't bind to haemoglobin very strongly is that the oxygen should be released in an environment where the oxygen concentration is low. Just strongly enough to take it up, but not too strong so that it doesn't let go.

    I remember a few years ago where I actually had to do the calculations of these interactions.. curves etc.
  10. Frankly Monique, i didn't get what you are talking about.
    Now you are breating.
    You take the oxygen into your lungs, it gets attached to the haemoglobin.
    The haemoglobin runs in the blood, the oxygen is used by the cells, other gasses are take back to the lungs by teh haemoglobin.

    Where comes the part where you have to take oxygen from haemoglobin back to the enviroment ?
  11. There ya go. At this point, the oxygen must be able to leave the haemoglobin and diffuse into the cells, where it is used in reactions. If like CO, it binds too tightly to the haemoglobin, it can never get to the cells.
  12. Monique

    Monique 4,445
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    Correct, diffusion is the key. The bindingstrength and oxygen partial pressure have to be fine-tuned, so that the oxygen will come off the complex when the oxygen concentration is cells is below a certain value, but it will stay attached if the cells don't need oxygen.
  13. Ahh, i thought you were talking about oxygen concentration in Air.
    Dumb me !
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