Biliverdin

Biliverdin is a green tetrapyrrolic bile pigment, and is a product of heme's catabolism. The heme is broken down by heme oxygenase to form biliverdin, which is then reduced to bilirubin by biliverdin reductase.

Structure and Properties

Biliverdin is a linear tetrapyrrole, which means it has four pyrrole rings connected by methine bridges. It has a deep green color due to the presence of conjugated double bonds that absorb light in the visible spectrum.

Biosynthesis

The biosynthesis of biliverdin is a part of the heme degradation pathway. The enzyme heme oxygenase cleaves the heme ring at the alpha methene bridge to form biliverdin. This reaction also releases iron and carbon monoxide.

Biological Role

Biliverdin has several important roles in the body. It is a precursor to bilirubin, which is a major pigment found in bile. Biliverdin also has antioxidant properties, and can help to protect cells from damage by reactive oxygen species.

Clinical Significance

In humans, an excess of biliverdin in the blood can lead to a condition known as hyperbiliverdinemia, which can cause the skin and eyes to appear green. This condition is extremely rare, and is usually associated with liver disease or certain genetic disorders.

See Also

• Heme
• Bilirubin
• Heme oxygenase
• Biliverdin reductase
• Hyperbiliverdinemia