10 - Biochemistry - Schmid - Heme Structure And Function - Ch. 3-4

Front 1

Structure of heme

Back 1

complex of Fe held at center by bonds to 4 nitrogens of porphyrin ring

Heme can do 2 additional bonds, one on each side of planar prophyrin ring

In hemo and myoglobin, one binds histidine while the other binds oxygen

Front 2

Hemoglobin

Back 2

1) Has heme group bound by hydrophobic interactions, and iron as Fe2+, which binds oxygen.
2) α2β2 tetramer.
3) Positive cooperativity in binding causes greater “steepness” about the P50 point;
successive oxygens are easier to add. This increases the amount of oxygen bound in the
lungs and the amount delivered in the tissues.