Quiz
MO31 Phase 2 Metabolism
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Perguntas do quiz (11)
1Glucuronidation is [blank_start]conjugation[blank_end] with alpha-D-glucuronic acid provided by the co-factor UDP–glucuronic acid (UDPGA). It adds 3 [blank_start]-OH[blank_end] groups and 1 [blank_start]-COOH[blank_end] (negatively charged) group to a drug.
UDP-glucuronosyl transferase (UGT) enzymes are microsomal, situated with CYPs on the [blank_start]ER[blank_end]. They are [blank_start]low[blank_end] affinity, [blank_start]high[blank_end] capacity enzymes- Aconjugation
- B-OH
- C-COOH
- DER
- Elow
- Fhigh
2In glucuronidation, the added polar group of the drug acts as a nucleophile and attacks an electrophilic site on UDPGA.
- AVerdadeiro
- BFalso
3Glucuronides can be [blank_start]recycles[blank_end] through the liver. Glucuronides excreted into bile can be [blank_start]hydrolysed[blank_end] back to the parent drug or a metabolite by [blank_start]alpha-glucuronidases[blank_end] present in gut microflora. Drug or Phase 1 metabolite (aglycone – glucuronide has been removed) undergoes [blank_start]reabsorption[blank_end] into the portal circulation. Aglycone is then available for another cycle through the liver. The end result is an [blank_start]extension[blank_end] of the half life of elimination and (if
active) the [blank_start]duration[blank_end] of action.- Arecycled
- Bhydrolysed
- Calpha-glucuronidases
- Dreabsorption
- Eextension
- Fduration
4Sulfation is important in the transport and metabolism of catecholamines, steroids, [blank_start]bile[blank_end] acids, [blank_start]phenolic[blank_end] drugs and other xenobiotics. The total pool of inorganic sulfate is [blank_start]limited[blank_end] and at high doses of drug [blank_start]glucuronidation[blank_end] predominates. The enzyme of sulfation, [blank_start]sulfotransferase[blank_end] (SULT) is polymorphic with 2 major isoforms SULT1 and SULT 2. They are [blank_start]high[blank_end] affinity, [blank_start]low[blank_end] capacity enzymes.
- Aphenolic
- Bbile
- Climited
- Dglucuronidation
- Esulfotransferase
- Fhigh
- Glow
5Phenols are more reactive than alcohols because they are more acidic, which makes them a better nucleophile.
- AVerdadeiro
- BFalso
6Methylation occurs at [blank_start]O, N and S[blank_end] to form metabolites that are equally or more active than the parent compound, removing an [blank_start]H[blank_end] and replacing with a [blank_start]CH3[blank_end]. Mainly occurs with [blank_start]endogenous[blank_end] compounds rather than drugs. Uses the cofactor ([blank_start]SAM or SAMe[blank_end]) and enzymes called methyl transferases. Does not increase [blank_start]polarity[blank_end] of compound. Has several isozymes mostly [blank_start]specific[blank_end] for a specific substrate.
- AO, N and S
- BH
- CCH3
- Dendogenous
- ESAM or SAMe
- Fpolarity
- Gspecific
7Catechol O-Methyltransferase (COMT) transfers a methyl group to the para- and less frequently the meta- phenolic group of catecholamines.
- AVerdadeiro
- BFalso
8Acetylation is mediated by [blank_start]N-acetyltransferases[blank_end], NAT1 and NAT2. NAT2
is expressed only in the [blank_start]liver[blank_end] whereas NAT1 is expressed throughout the [blank_start]body[blank_end]. [blank_start]Secondary[blank_end] amines are not acetylated.- AN-acetyltransferases
- Bliver
- Cbody
- DSecondary
9Choose the incorrect statement about amino acid conjugation.
- ACatalysed by transacetylase
- BEnzymes reacts with amino group of amino acid, usually glycine
- CXenobiotic carboxylic acids are either glucuronidated or conjugated with glycine, glycine conjugation is preferred at high doses
10Glutathione Conjugation:
• Some xenobiotics and highly reactive species are conjugated with glutathione (GSH) ([blank_start]Glu-Cys-Gly[blank_end]).
– catalysed by [blank_start]glutathione-S-transferases[blank_end] (GSTs)
• The reaction is “protective” – it [blank_start]inactivates[blank_end] potentially toxic electrophilic compounds preventing them from reacting with [blank_start]nucleophilic[blank_end] centres in macromolecules e.g. proteins & nucleic acids. Electrophiles include:
– Aromatic / aliphatic [blank_start]halogens[blank_end]
– nitro groups
– Alkenes / [blank_start]Epoxides[blank_end]
– Sulfonic acid [blank_start]esters[blank_end]
– Reactive intermediates- AGlu-Cys-Gly
- Bglutathione-S-transferases
- Cinactivates
- Dnucleophilic
- Ehalogens
- FEpoxides
- Gesters
11Enzyme Polymorphism in DMEs:
DMEs are polymorphic and individuals have different drug metabolising [blank_start]phenotypes[blank_end]. Polymorphism exists due to one or more [blank_start]single nucleotide differences[blank_end] (SNPs) in the genes giving rise to different alleles some of which express inactive enzymes. Polymorphisms are present to different extents in different [blank_start]ethnic[blank_end] groups.
Individuals can be poor metabolisers (PMs) or fast metabolisers (FMs):
– PMs can experience [blank_start]toxicity[blank_end]
– FMs can experience [blank_start]therapeutic drug failure.[blank_end]
Identification of genotype allows the prediction of drug response, i.e. to [blank_start]individualised[blank_end] drug therapy.- Aphenotypes
- Bsingle nucleotide differences
- Cethnic
- Dtoxicity
- Etherapeutic drug failure.
- Findividualised
Informações
- Descrição
- PHCY211 (Molecules) Quiz sobre MO31 Phase 2 Metabolism, criado por Mer Scott em 02-06-2018.
- Autor
- Mer Scott
- Idioma
- English
- Visualizações
- 6
- Etiquetas
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