Heme group

Heme Group is a crucial component of various proteins, including hemoglobin, myoglobin, and cytochromes. It is a complex molecule that contains an iron atom at its center, surrounded by a large organic ring called a porphyrin. The heme group is responsible for the red color of blood and is essential for life in most organisms.

Structure

The heme group is a large, flat molecule made up of four pyrrole rings linked together by methine bridges to form a larger ring, known as a porphyrin. At the center of this porphyrin ring is an iron atom, which can bind to a molecule of oxygen. The iron atom is coordinated to four nitrogen atoms in the plane of the porphyrin and to two other groups above and below the plane.

Function

The primary function of the heme group is to bind to and transport oxygen in the blood. This is accomplished through the protein hemoglobin, which contains four heme groups. Each heme group in hemoglobin can bind to one molecule of oxygen, allowing each hemoglobin molecule to carry four molecules of oxygen. The heme group is also found in myoglobin, a protein that stores oxygen in muscle cells, and in various cytochromes, which are involved in electron transport and drug metabolism.

Role in Disease

Defects in the synthesis of the heme group can lead to a variety of diseases, including porphyria, a group of rare genetic disorders that affect the nervous system and skin, and sideroblastic anemia, a form of anemia in which the body has enough iron but cannot incorporate it into hemoglobin.

See Also

• Hemoglobin
• Myoglobin
• Cytochromes
• Porphyrin
• Porphyria
• Sideroblastic anemia

References

Heme group Resources
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