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52 Cards in this Set
- Front
- Back
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What is a suicide substrate?
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An enzyme inhibitor that has latent functionality that becomes reactive only after inhibitor binding and being acted upon by the normal catalytic machinery of the enzyme.
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The bacterial activity of penicillin and other B-lactam antibiotics is due to their:
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Irreversible inhibition of D-ala-D-ala-transpeptidase in cell wall biosynthesis.
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What is a prodrug?
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A pharmacologically inactive compound which is metabolically converted in vivo to a pharmacologically active compound.
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Reverse transcriptase, a retroviral enzyme and an important target for anti-AIDS drugs, is an enzyme that produces ____ from an _____ template.
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DNA; RNA
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What can be said about the amide functional group?
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An amide is neutral at physiological pH, it can participate in hydrogen bonding, its electronic structure is a hybrid of two resonance structures, and it can be hydrolyzed by a strong acid or base to an amine and a carboxylic acid.
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What is the major pharmacological activity of acetylsalicylic acid (aspirin)?
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It is a non-steroidal anti-inflammatory non-selective cyclooxygenase inhibitor.
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What is an affinity label?
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An enzyme inhibitor in which a substrate is modified so that it contains a chemically reactive electrophile which can then bind to and subsequently react with the enzyme active site.
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What is the activity of Angiotensin converting enzyme (ACE)?
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It is a carboxydipeptidase that cleaves the C-terminal 2-amino acids from its peptide substrate.
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What is a second messenger?
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A compound that is produced inside the cell in direct response to the binding of a neurotransmitter or hormone to its extracellular receptor.
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What is a soft-drug?
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A biologically active drug molecule which is designed to be predictably inactivated by it metabolism to pharmacologically inactive and non-toxic compounds.
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Why is 5-fluorouracil a highly effective anti-tumor drug?
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Because it inhibits the biosynthesis of thymidine 5'-triphosphate.
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The pharmaclogical activity of succinyl choline is best described as?
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A cholinergic antagonist and a neuromuscular blocking agent.
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The G-protein coupled receptor is best described as?
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A single polypeptide chain, which possesses 7-hydrophobic membrane crossing a-helices.
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The steroid prednisolone is often administered as the prodrug prednisolone phosphate. What is the prodrug form designed to do?
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To increase the water solubility of the drug to allow it to be given in an aqueous solution.
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What is the mechanism by which the actions of acetylcholine are terminated shortly after its release in the synapse?
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It is rapidly hydrolyzed into acetate and choline by acetylcholinesterase.
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Which of the classes of receptors is responsible for the regulation and induction of drug metabolizing enzymes in response to administration of a xenobiotic molecule?
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Orphan nuclear receptors.
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Describe the nitrogen mustard that would be most effective at crosslinking DNA?
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A small, bi-functional, symmetrical nitrogen mustard having the same substituent on each arm.
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Which functional groups will participate in hydrogen bonding?
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Those that exhibit characteristic dipole effects like those that contain oxygen, nitrogen, sulfur, etc. Not plain alkyl groups that are non-polar.
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Which compounds exhibit the highest potency as DNA intercalating agents?
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Triple benzene ringed compounds, the flatter the better.
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Knowing that chlorambucil is a bi-functional alkylating agent, what is the mechanism through which the anti-neoplastic drug chlorambucil produces its characteristic anti-tumor effect?
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Its ability to chemically cross-link double helical DNA.
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Which enzyme is inhibited by aminopterin and methotrexate?
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Dihydrofolate reductase
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Are barbituates like aminobarbitol acids, bases, or neutral compounds.
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Acids
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What is the main inhibitor of b-lactamase?
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Clavulinic acid
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What about a compounds structure would make it a good affinity label for chymotrypsin?
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A compound that has the large hydrophobic region to fit into the binding pocket, a good electrophile, and a good leaving group.
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What about inhibitors of carboxypeptidase A make them good inhibitors?
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The best CPA inhibitors have hydrophobic bonding region, have a good nucleophile to bind the zinc, and have the characterstic binding region.
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What is first pass metabolism?
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The ability of the intestines and the liver to metabolize most of a dose of some orally administered compounds before they reach general circulation.
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What is an orphan nuclear receptor?
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Soluble proteins that bind drugs and xenobiotics and regulate CYP450 gene expression.
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What is a lead compound?
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The first compound discovered which possesses a desired pharamcological activity, often also exhibiting side effects or toxicity.
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What is Phase I metabolism?
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Refers to the process in which xenobiotics are modified chemically through oxidation, hydrolysis, or occasionally reduction to introduce new fucntional groups, especially -OH.
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What is Phase II metabolism?
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The process in which hydrophllic molecules - glucuronic acid, sulfate, or amino acids - are attatched to a drug or its metabolite to increase its water solubility.
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What is drug potency?
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The concentration at which a drug elicits its characteristic biological response.
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What is drug efficacy?
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Describes the ability of the D.R complex to initiate a biological response. (Agonist = 1, Antagonist = 0)
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What is the occupancy theory?
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A theory that suggests that biological effect of an agonist is associated with its combination with its specific receptor and that the magnitude of the biological response is proportional to the amount of D.R complex formed.
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What is the lock & key principle?
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A way of looking at receptor-ligand interactions, in which we imagine that the receptor and ligand "fit together" as complementary molecular surfaces.
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What are bioisosteres?
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Groups that possess approximately equal molecular shapes, volumes, and electronic distribution and therefore exhibit similar physical and pharmacological properties.
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What is a racemic mixture?
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Refers to a mixture of equal quantities of the two possible optical isomers of a compound.
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What is the bioactivation of carcinogens?
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The production of an undesired and toxic metabolite as a result of phase I drug metabolizing reactions on polycylic aromatic hydrocarbons.
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What is an antagonist?
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A drug which competes with the agonist for a common binding site, yet it can't trigger a receptor mediated response.
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What are second messengers?
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Signalling compounds produced inside the cell in direct response to agonist binding at a G-protein coupled receptor.
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What is resolution?
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The separation of a racemic mixture into pure individual isomers.
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True or False: Fluorine is a poor bioisostere for hydrogen because their bond lengths and radius are very different.
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False
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True or False: Peptide hormones like angiotensin II as well as peptide neurotransmitters are usually produced from protein precursors by highly specific proteases.
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True
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True or False: Competitive antagonists tend to be bigger molecules - higher molecular weight with large hydrophobic groups - than are pure agonists.
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False
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True or False: Enzymes can not be used as therapeutically as drugs because of their high molecular weight and sensitivity to proteolysis in vivo.
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False
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True or False: Affinity chromatography can be used to purify enzymes as well as receptors.
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True
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True or False: Non-competitive antagonists compete with agonists for a common binding site.
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False
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True or False: For a simple receptor agonist, EC50 will equal Kd, the dissociation constant for the receptor.agonist complex.
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True
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True or False: The smaller the value of log P for a compound, the more hydrophobic the compound is.
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False
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True or False: X-ray crystallographic analysis has produced many 3-dimensional models at atomic resolution for water soluble enzymes.
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True
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True or False: Foods or herbal medicines can contain compounds which will affect the metabolism of drugs taken at the same time.
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True
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Which type of enzyme inhibitor has the same x-intercept, but a different y-intercept, and a different slope on a Lineweaver-Burke plot?
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A non-competitive enzyme.
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Which type of enzyme inhibitor has the same y-intercept, but a different x-intercept, and a different slope on a Lineweaver-Burke plot?
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A competitive enzyme
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