Which enzyme is primarily responsible for the conversion of bilirubin to its conjugated form?

The enzyme primarily responsible for the conversion of bilirubin to its conjugated form is bilirubin uridine diphosphate-glucuronosyltransferase (UGT). This enzyme catalyzes the process of glucuronidation, where bilirubin, a byproduct of heme degradation, is converted from its unconjugated (lipophilic) form to a conjugated (water-soluble) form. This conversion is crucial because the conjugated bilirubin can be readily excreted in bile and urine, facilitating its elimination from the body.

Unconjugated bilirubin is potentially toxic and can lead to conditions like jaundice if accumulated, making the action of UGT essential for maintaining proper bilirubin levels and overall metabolic health. Disorders associated with dysfunctions of this enzyme can lead to genetic conditions such as Gilbert's syndrome or Crigler-Najjar syndrome, characterized by elevated levels of unconjugated bilirubin.

The other enzymes listed do not play a central role in the conjugation of bilirubin. Glucuronidase is involved in the degradation of glycosaminoglycans and does not participate in bilirubin conjugation. Sulfotransferase primarily acts on substrates for sulfate conjugation in various metabolic