Xenobiotics Flashcards
What are Xenobiotics?
A compound that is foreign to the body.
What are the medically relevant classes of Xenobiotics?
Pharmaceuticals, chemical carcinogens, petroleum products, and some pesticides.
What does “Xeno” mean?
Stranger
What are the 2 phases of Xenobiotic metabolism?
Phase 1: involves isoforms of cytochrome p450s. The chief reaction in phase 1 is Hydroxylation…Introducing oxygen…and polar bonds.
Phase 2: Involves conjugation reactions. Phase 2 reactions add materials to make xenobiotics more water soluble.
Cytochrome p450s are__________?
mono-oxygenases (a group of hemoproteins)
Where are the enzymes found?
In the Endoplasmic Reticulum and the mitochondria
The highest levels of cytochrome p450s are found where?
In the liver
The limited number of enzymes that must recognize many chemical targets speaks to the idea of….?
The wide range of substrate specificities of cytochrome p450s
How are Phase 2 reactions excreted?
Via urine or the bile
What are the 6 principle types of Phase 2 reactions?
Glutathionation, glucuronidation, addition of amino acids, acetylation, sulfation, and methylation
What enzyme is responsible for a glucuroniation?
UDP-glucuronosyltransferase (UGT)
What enzyme is responsible for the addition of amino acids?
Acyl synthetase
What enzyme is responsible for the acetylation
transacetylase
What enzyme is responsible for the sulfation?
Sulfotransferase
What enzymes are responsible for the methylation?
Catechol-O-methyltransferase (COMT) or Phenylethanolamine N-methyltransferase (PNMT)
