hemoglobin!

For all your heme-holding needs! This is actually carbonmonoxy hemoglobin, which is the reason carbon monoxide is so dangerous; carbon monoxide binds really easily to the spot on hemoglobin that's supposed to be reserved for oxygen. So instead of having nice oxygenated blood, you have crummy carbon-monoxated blood. Which obviously sucks for all your bodily functions that require oxygen.

Model from the Protein Data Bank. I (relatively) quickly messed with it.


[Chimera & 3ds Max 2009]