How are mercapturic acids created?
Mercapturic acid is a condensation product formed from the coupling of cysteine with aromatic compounds. It is formed as a conjugate in the liver and is excreted in the urine. Glutathione adducts lose glutamate and glycine portions, and are acetylated to form mercapturic acids, which are excreted.
How does metabolism of GSH conjugates to Mercapturic acid?
2): Glutathione conjugates are transported to the kidney, where they are rapidly metabolized to cysteine conjugates by the abundant yGT and dipeptidase activities in this organ; cysteine conjugates are reabsorbed from the renal tubular lumen, returned to the circulation, and transported back to the liver for …
Is mercapturic acid toxic?
Mechanism of Toxicity Mercapturic acids, acrylic acid, or glyceraldehyde can also be produced. The last three metabolites have been detected only in in vitro experiments. Acrolein affects primarily the respiratory tract, producing irritation in the mucous membranes of the sensory nerve endings.
What is the mercapturic acid pathway?
The mercapturic acid pathway is a major route for the biotransformation of xenobiotic and endobiotic electrophilic compounds and their metabolites. Several renal transport systems facilitate the urinary elimination of mercapturic acids; urinary mercapturic acids may serve as biomarkers for exposure to chemicals.
Is GSH an antioxidant?
Glutathione (GSH) is often referred to as the body’s master antioxidant. Composed of three amino acids – cysteine, glycine, and glutamate – glutathione can be found in virtually every cell of the human body. A primary function of glutathione is to alleviate this oxidative stress.
What is the meaning of glutathione conjugation?
Glutathione conjugation is an important detoxification mechanism. Enzymatic reactions involving glutathione are catalyzed by the enzyme glutathione-S-transferase. It catalyzes the reaction between glutathione and aliphatic of aromatic epoxides and halides.
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 cysteine an amino acid?
Cysteine is a non-essential amino acid important for making protein, and for other metabolic functions. It’s found in beta-keratin. Cysteine has antioxidant properties.
Which enzyme is responsible for glucuronidation?
UDP-glucuronosyltransferase 1A1 is the principal enzyme responsible for etoposide glucuronidation in human liver and intestinal microsomes: structural characterization of phenolic and alcoholic glucuronides of etoposide and estimation of enzyme kinetics. Drug Metab Dispos. 2007 Mar;35(3):371-80. doi: 10.1124/dmd.
What is the function of glucuronidation?
Glucuronidation is a major mechanism for the formation of water-soluble substrates from xenobiotics, leading to their elimination from the body in bile or urine.