Page 130 - The Miracle of Protein

128 THE MIRACLE OF PROTEIN

When hemoglobin binds with oxygen, it goes through various
structural changes. The left picture shows the normal state of
hemoglobin, and the right shows it after it binds with the oxygen.

sential. Might there be any alternatives to hemoglobin? None
of the many other oxygen-carrying molecules which occur in
the blood of invertebrates, such as the copper-containing pro-
teins of the mollusks, come close to the efficiency of hemoglobin
in transporting oxygen in blood. As Ernest Baldwin comment-

ed, "Mammalian hemoglobin is far and away the most success-
ful of the respiratory pigments from this point of view"... The
evidence is consistent with the possibility that hemoglobin is
the ideal and unique respiratory pigment for metabolically ac-
tive air-breathing organisms such as ourselves. 57
The way that a collection of molecules can make this dis-

tinction in a pitch-black environment unbelievably larger than
itself, distinguishing between oxygen and other molecules, and
able to bind to oxygen in the most appropriate way reveals the
existence of a superior wisdom and design.