Question

(a) Obtain the atomic coordinates for hemoglobin and myoglobin. Measure thier dimensions, identify the different subunits and the heme groups.

(b) Calculate the mean spacing between hemoglobin molecules inside a red blood cell. How does this spacing compare with the size of a hemoglobin molecule?

Answer 1

Answer

1)The site at which oxygen binds to both hemoglobin and myoglobin is the heme.
2)At the center of the heme is an Fe(II) atom.
3) Four of the six coordination sites around this atom are occupied by nitrogen atoms from a planar porphyrin ring.
4) The fifth coordination site is occupied by a nitrogen atom from a histidine side chain on one of the amino acids in the protein.
5)The last coordination site is available to bind an O2 molecule.

Diameter of red blood cell = 5 microns 3*10^8 hemoglobin molecules in each red blood cell Volume of hemoglobin molecule = 8.71*10^-26 m