CHAPTER 32: HEME BIOSYNTHESIS

The process by which heme, a compound derived from porphyrins, is synthesized primarily in the bone marrow and liver.

Heme biosynthesis

Cyclic compounds with a high affinity for binding metal ions, usually ferrous or ferric iron, that serve as the precursor for heme biosynthesis.

Porphyrins

An erythrocytic iron porphyrin attached to the protein globin, responsible for carrying oxygen in the blood.

Hemoglobin (Hb)

A protein similar in structure to hemoglobin that imparts red color to aerobic muscle fibers and possesses the ability to combine reversibly with oxygen.

Myoglobin

Iron porphyrin proteins that act as electron transfer agents in cellular oxidation-reduction reactions.

Cytochromes

Ubiquitous iron porphyrin enzymes that degrade hydrogen peroxide in mammals.

Catalases

A magnesium-containing porphyrin that is an important photosynthetic pigment in plants.

Chlorophyll

An enzyme involved in the first step of heme biosynthesis, catalyzing the condensation of succinyl-CoA and glycine to form D-ALA.

D-aminolevulinate (D-ALA) synthase

Also known as ferrochelatase, this enzyme catalyzes the final step in heme biosynthesis, incorporating iron into protoporphyrin IX.

Heme synthase

The phenomenon in which a decrease in pH causes a shift in the oxygen dissociation curve of hemoglobin, resulting in decreased oxygen saturation at any given partial pressure of oxygen.

Bohr effect