Final answer:
The enzyme responsible for conjugating bilirubin in the liver is UDP glucuronyl transferase. It converts bilirubin into a water-soluble form for excretion via the bile, aiding in detoxification. Deficiencies in this enzyme can lead to jaundice and other hepatic diseases.
Step-by-step explanation:
The enzyme in the liver responsible for conjugating bilirubin within the hepatocyte is UDP glucuronyl transferase. This enzyme facilitates the conversion of bilirubin into a water-soluble form by adding glucuronic acid to it. Initially, bilirubin is bound to albumin in the blood to form an albumin-bilirubin complex, which is transported to the liver. In the liver, bilirubin is separated from albumin and taken up by hepatocytes where UDP glucuronyl transferase catalyzes its conjugation to glucuronic acid, forming bilirubin monoglucuronide and subsequently bilirubin diglucuronide.
The conjugated bilirubin is then excreted into the bile and eventually into the intestine where it is transformed into stercobilinogen and then to stercobilin, which provides the brown color to feces. Disorders such as Crigler-Najjar syndrome and Gilbert's disease involve deficits in UDP glucuronyl transferase activity, leading to problems with bilirubin conjugation and excretion.