What substance reacts with bilirubin to form conjugated bilirubin?

Bilirubin is a breakdown product of heme, primarily derived from the degradation of hemoglobin in red blood cells. Once bilirubin is produced in the liver, it undergoes a crucial process called conjugation to become more water-soluble for easier excretion from the body.

The substance that reacts with bilirubin to form conjugated bilirubin is glucuronic acid. This reaction is facilitated by the enzyme UDP-glucuronosyltransferase, which catalyzes the conjugation of bilirubin with glucuronic acid to create bilirubin diglucuronide. Conjugated bilirubin is then excreted into bile and subsequently into the intestine, where it can be further processed or eliminated.

When compared with the other substances listed, only glucuronic acid plays this specific role in the conversion of bilirubin into its conjugated form. Glutathione is involved in various biochemical processes, including detoxification, but does not play a direct role in bilirubin conjugation. Similarly, sulfate and acetic acid are not involved in the metabolic conversion of bilirubin to its conjugated form. This biochemical pathway underscores the importance of glucuronic acid in the metabolism and elimination of bilirubin from the body.