bio chem 2

alpha2 beta 2; little contact between alpha1 and alpha 2, or beta 1 and beta 2

about 0.4 outside heme plane; rion with 5 ligands is too large to fit exactly in plane of heme; O2 binding reduces size of iron and it can move into plane

lowers Hb affinity for oxygen (promotes oxygen release); more oxygen is needed to make energy; modulate amount of oxygen from hemeglobin to myoglobin