Bilirubin, an end product of heme catabolism, is primarily eliminated via glucuronic acid conjugation by UGT1A1. Impaired bilirubin conjugation, caused by inhibition of UGT1A1, can result in clinical consequences, including jaundice and kernicterus.
What is function of uridine diphosphate Glucuronosyltransferase?
The uridine diphosphate (UDP)-glucuronosyltransferases (UGT) are a family of enzymes that catalyse the covalent addition of glucuronic acid to a wide range of lipophilic chemicals.
How is UDP glucuronate formed?
UDP-glucuronic acid is formed from UDP-glucose by oxidation of its glucose moiety. UDP-glucuronate reacts with metabolic waste products and drugs; this results in a water-soluble conjugate called a glucuronide.
How is UDPGA formed?
The UDPGA is formed in the cytosol from glucose-1-phosphate in a two-step reaction (figure 4.48). The first step, addition of the UDP, is catalysed by UDP glucose pyrophosphorylase, the second step by UDP glucose dehydrogenase.
Is glucuronic acid conjugated bilirubin?
Conjugated. In the liver, bilirubin is conjugated with glucuronic acid by the enzyme glucuronyltransferase, first to bilirubin glucuronide and then to bilirubin diglucuronide, making it soluble in water: the conjugated version is the main form of bilirubin present in the “direct” bilirubin fraction.
What is the function of glucuronic acid?
A form of a type of sugar called glucose that helps remove harmful substances from the body. Glucuronic acid and the harmful substance combine in the liver and then are passed in the urine.
What induces UDP-Glucuronosyltransferase?
Glucose induces intestinal human UDP-glucuronosyltransferase (UGT) 1A1 to prevent neonatal hyperbilirubinemia.
What is UDP glucuronyl transferase deficiency?
Deficiency, UDP-glucuronosyltransferase: Underactivity of a liver enzyme that is essential to the disposal of bilirubin (the chemical that results from the normal breakdown of hemoglobin from red blood cells).
What is uronic acid pathway?
Uronic acid pathway is an alternative oxidative pathway for glucose metabolism. It catalyzes the conversion of glucose to glucuronic acid, ascorbic acid, and pentoses. It does not lead to the formation of ATP.
What does a glucuronide do?
The human body uses glucuronidation to make a large variety of substances more water-soluble, and, in this way, allow for their subsequent elimination from the body through urine or feces (via bile from the liver). Hormones are glucuronidated to allow for easier transport around the body.
What is Glucuronidation reaction?
Glucuronidation is a conjugation reaction whereby glucuronic acid, derived from cofactor UDP-glucuronic acid, is covalently linked to a substrate containing a nucleophilic functional group. The resultant metabolite, called a glucuronide, is usually excreted in bile and urine.
Is Diglucuronide a conjugate of bilirubin?
Bilirubin glucuronide itself belongs to the category of conjugated bilirubin along with bilirubin di-glucuronide. However, only the latter one is primarily excreted into the bile in the normal setting.
What is uridine diphosphate glucuronic acid used for?
Uridine diphosphate glucuronic acid is a nucleoside diphosphate sugar which serves as a source of glucuronic acid for polysaccharide biosynthesis. It may also be epimerized to UDP Iduronic acid, which donates Iduronic acid to polysaccharides. In animals, UDP glucuronic acid is used for formation of many glucosiduronides with various aglycones.
How do UDP- and UDP- affect bilirubin conjugation patterns?
Bilirubin and UDP- glucuronic acid concentrations both appear to be pivotal in regulating the synthesis of individual bilirubin glucuronides and hence the patterns of bilirubin conjugates excreted in bile. Hepatic bilirubin uridine diphosphate glucuronyl-
How is betabilirubin conjugated to glucuronic acid?
Bilirubin is conjugated within the hepatocyte to glucuronic acid by a family of enzymes, termed uridine-diphosphoglucuronic glucuronosyltransferase (UDPGT). The process of glucuronidation is one of the many crucial detoxification mechanisms of the human body.
What is the isoform of bilirubin glucuronidation?
Many different isoforms of UDPGT exist, but the physiologically important isoform in bilirubin glucuronidation is UDPGT1A1. The enzyme esterifies two glucuronide moieties to the propionic acid side chains of bilirubin. Under normal conditions, bilirubin diglucuronide is the predominant molecule synthesized.
