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PHRD5915 Drug Design Lecture 4 - Phase II Metabolism
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what the MAO system does to neurotransmitters
deamination
4 locations in which alcohol detox occurs
1) microsomes
2) cytosol
3) peroxisomes
4) mitochondria
where CYP2E1 works during EtOH detox
microsomes
where ADH works during EtOH detox
cytosol
where catalase works during EtOH detox
peroxisomes
where ALD2 & ALDH1B1 work during EtOH detox
mitochondria
vitamin K analog involved in quinone cycling
menadione
how quinone-cycling causes toxicity (2)
1) semiquinone radical causes protein/DNA damage
2) hydroxyl radical (HO
.
) causes protein/DNA damage and lipid peroxidation
exception to the rule that oxidative biotransformations require reduced cofactors NADPH and NADH
peroxidases that couple the reduction of H
2
O
2
and lipid hydroperoxides to the oxidation of other substrates => COOXIDATION
2 activities of Prostaglandin H Synthase
1) cyclooxygenase
2) hydroperoxidase
cyclooxygenase function of Prostaglandin H Synthase in the presence of arachidonic acid
arachidonic acid -> PGG
2
hydroperoxidase function of Prostaglandin H Synthase in the presence of arachidonic acid
PGG
2
-> PGH
2
product of PGH Synthase w/ anti-thrombotic activity
PGH
2
(prevents platelets from aggregating)
how oxidative stress can be caused by xenobiotics
take electrons from PGG
2
& form free radicals
**important in neurodegeneration**
reduces free radicals formed by xenobiotics
GSH (glutathione)
what is the precursor to O-glucuronide & N
+
-glucuronide?
UDP-
-D-glucuronic acid
what transfers glucuronic acid after it is cleaved to a substrate
uracil-glucuronic transferase (UGT)
product of a glucuronidation
glucuronide
universal donor for
all
sulfation reations
PAPS (3'-phosphoadenosine-5'-phosphosulfate)
pyrophosphate cleavage
2 phosphates cleaved in a rxn
3 enzymes needed for glutathione conjugation
1) transpeptidase
2) peptidase
3) acetylase
simplest of all amino acids
glycine
necessary for glycine conjugation
Coenzyme-A associated w/ AMP
where CoA binds to carboxylic acid in glycine conjugation
sulfur from sulfhydryl group
needed for glycine conjugation (3)
1) acyl-CoA synthase (replaces -OH w/ AMP, then CoASH)
2) CoA (activates carboxyl group, then is leaving group)
3) N-acyltransferase (takes off CoA)
thiol metabolism
thiol -> disulfide
(by oxidation)
enzyme that cleaves disulfide bond
glutathione reductase
enzyme that oxidizes a substrate
P450 (monooxygenase)
requirement for conjugation
drug/molecule has to be hydroxylated first
leaving groups in glucuronidation
phosphate groups
uracil
substrates you can conjugate glucuronic acid to
3
ROH
R
3
N
Author
daynuhmay
ID
266383
Card Set
PHRD5915 Drug Design Lecture 4 - Phase II Metabolism
Description
Phase II Metabolism
Updated
2014-03-14T05:55:15Z
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