PCL201H1 Lecture 19: Lecture 19 Biotransformation IV

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azuresquirrel208

22 Apr 2012

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Induction/inhibition of enzyme activity affects drug biotransformation capacity. Important for drugs with narrow therapeutic index (e. g. warfarin (blood thinner), Potent inducers of drug-metabolizing enzymes: tcdd (environmental toxicant) Metabolism of inducer is accelerated at high doses. Cyp1a1 activity in human placenta is high in smokers. The process of enzyme induction refers to increase in gene transcription. Phenobarbital decreases plasma [dicumarol], efficacy: dicumarol (blood thinner, phenobarbital (cyp inducer, sedative, therapeutic efficacy affected with dose of phenobarbital, drug-drug interaction: one drug induces the metabolism of another drug. Hepatic toxicity of acetaminophen is decreased by inhibitors of the constitutive. Androstone receptor (car), the receptor that mediates p450 induction by phenobarbital and related compounds. Car mediates cyp induction by a herbal preparation. Indinavir (treats hiv) and st. john"s wort: st. john"s wort decreases the bioavailability of indinavir, st. john"s wort interacts with cyclosporin (immunosuppresser, makes sure heart transplant not rejected, st. john"s wort metabolizes cyclosporin.

Related Questions

Dave has a particularly efficient CYP2D6 enzyme system in his liver. Based on this information one would predict that he would:

A. Be efficient at metabolizing most psychoactive medications

B. Have trouble with the biotransformation of many drugs

C. not be particularly efficient at metabolizing psychoactive medications

D. be efficient at metabolizing some psychoactive medications more than others

indigogoose304

1. What is the term when the product of a biochemical pathway inhibits the activity of the first enzyme of a pathway?

		feedback inhibition.
		activator inhibition.
		diffusional regulation.
		enzyme activation.

2. Through control of gene expression, prokaryotes respond to changing __________ conditions.

		internal
		protein
		environmental
		genetic

3. A protein that negatively regulates transcription by binding to the operator is known as the

		operon
		repressor
		activator
		inducer

4. During attenutation, when tryptophan levels are high, the ________ stem-loop forms and transcription ________ the trpL gene.

		1-2, ends just past
		3-4, ends just past
		1-2, continues beyond
		3-4, continues beyond

5. The process of turning on the expression of a gene in response to a substance in the environment is called:

		constituation.
		repression.
		induction.
		catabolism.

6. What is a function of some specific transcription factors?

		to bind to the promoter region of the gene to facilitate the proper alignment of the RNA polymerase
		to bind to the centromere to induce meiosis
		to bind to enhancer regions to help regulate gene transcription
		to bind to the operator to recruit sigma factor

7. How does exposing an E.coli cell to glucose affect the regulation of the lac operon via CAP?

		cAMP binds to CAP and transcription is increased.
		cAMP binds to CAP and transcription is decreased.
		cAMP does not bind to CAP and transcription is increased.
		cAMP does not bind to CAP and transcription is decreased.

8. The lac repressor protein works when mutations in the repressor gene and structural genes are:

		in cis or in trans.
		in trans only.
		in cis only.
		in both prokaryotes and eukaryotes.

scarletwombat949

Benzo[a]pyrene, the cancer-causing agent in cigarette smoke, is a powerful mutagen. Benzo[a]pyrene itself is relatively harmless, but it is metabolized in the liver to produce active molecules that react covalently with DNA. In an experiment, benzo[a]pyrene is incubated with a mixture of liver enzymes to form its genotoxic metabolites. These metabolites are added to E. coli cells that have a mutation in a gene encoding an enzyme of the serine-synthesizing pathway (i.e., the cells are serine auxotrophs, requiring serine for growth). When the treated cells are grown on serine-containing medium, the results show that the benzo[a]pyrene metabolites kill cells in a dose-dependent manner. When treated and untreated serine-auxotrophic cells are plated separately on serine-free media, the cells treated with benzo[a]pyrene metabolites show a 10- to 100-fold increase in survivors compared with untreated cells. Explain these results.Compare and contrast mismatch repair in E. coli and eukaryotes.

List two reasons translesion sysnthesis tends to be mutagenic.

Describe, in detail, nucleotide excision repair. Include especially ways the damage can be recognized.

PCL201H1 Lecture 19: Lecture 19 Biotransformation IV

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