What is the primary function of UDP glucuronyl transferase?

The primary function of UDP glucuronyl transferase is the conjugation of bilirubin. This enzyme plays a crucial role in the metabolism and detoxification of various substances, including bilirubin, which is a breakdown product of hemoglobin. By facilitating the conjugation of bilirubin to glucuronic acid, UDP glucuronyl transferase increases its water solubility, allowing for easier excretion from the body via bile and urine. This process is vital in preventing the accumulation of bilirubin, which can lead to conditions such as jaundice when levels become elevated.

The other options provided relate to different metabolic pathways: the excretion of creatinine is primarily managed by the kidneys; the conversion of ammonia to urea occurs through the urea cycle, involving different enzymes; and the hydrolysis of proteins is conducted by various proteolytic enzymes, none of which involve UDP glucuronyl transferase. Therefore, the focus on bilirubin conjugation underscores the specific and essential role of this enzyme in the body.