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CASE FILES: BIOCHEMISTRY
B IO C H E M IS T R Y PE A R L S
Carbon monoxide poisoning interferes with O2 transport to tissues
and the interaction of O2 with cytochromes, especially the
cytochromes in the electron transport chain (ETC).
The four O2 binding sites of hemoglobin exhibit positive coopera-
tivity in binding O2, leading to the sigmoid shape of hemoglobin
dissociation curve.
The binding of the first molecule of O2 occurs with a modest affin-
ity but causes a conformational change that enhances hemoglo-
bin’s binding affinity for a second molecule of O2, and so on.
Carbon monoxide binds 220 times more avidly to hemoglobin than O2.
REFERENCES
Devlin TM, ed. Textbook of Biochemistry with Clinical Correlations, 5th ed. New
York: Wiley-Liss, 2002:577-82.
Goodman AG, Gilman LS, eds. The Pharmacological Basis of Therapeutics, 10th ed.
New York: McGraw-Hill, 2001.
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