Page 49 - The Miracle of the Blood and Heart
P. 49
F helix
Heme
Porphyrin Fe 2+ Porphyrin
O 2
The four heme groups in the hemo-
globin molecule are involved with bind-
ing and carrying oxygen. These heme
groups are initially parallel to one another,
but when they bind an oxygen molecule they
lose their parallel alignment and each causes
changes in the structure of the globin surrounding it.
Globin prevents oxygen links from forming among the iron
ions by the oxygen molecules' approaching one another.
Thanks to this extremely important precaution, the two
hemoglobin iron atoms are prevented from being oxi-
dized. The approximately 270 hemoglobin molecules
in every red blood cell take this important precaution
Adnan
constantly.
Oktar
47
