Page 216 - The Miracle in the Cell Membrane

The Miracle in the Cell Membrane

Hemoglobin's Oxygen Selection

The most important property of the protein hemoglo-
bin in the blood's erythrocyte cells is its ability to trap oxy-
gen atoms. Hemoglobin carefully selects oxygen mole-
cules from among the millions of molecules in the blood.
However, a hemoglobin molecule attaching to an oxygen
molecule would be oxidized and lose its function. For that
reason, hemoglobin traps the oxygen molecule with a spe-
cial technique, the result of a special Creation—not touch-
ing it at all, as if it were using tongs.
Hemoglobin consists of the assembly of four different
proteins, in which there are special iron atom-bearing sec-
tions. These regions that carry iron atoms are known as
heem (or haem) groups. The iron atoms in these heem
groups are the special tongs by which oxygen is held. Each
64
heem group can hold one oxygen molecule. Special folds
and angles within the molecule let the heem groups trap
oxygen without touching it and carry it to the tissues.
These angles change in specific proportions during the
binding process. 65

The hemoglobin molecule shown has a very
special structure created to carry oxygen
in the blood, and one that scientists speak
of with amazement:
"It would seem that in designing an oxygen-
transporting molecule from first principles
we are led inevitably to a molecule very like
hemoglobin. The evidence is consistent with the
possibility that hemoglobin is the ideal and unique respiratory pigment for
metabolically active air-breathing organisms. . . .The elegance of the way the
hemoglobin system functions is simply astounding, and a source of wonder to
everyone who is familiar with its intricate ingenuity." (Michael J. Denton,
Nature's Destiny, The Free Press, 1998, p. 202.)

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