Exam 1 Flashcards
Which phrase does not accurately describe the structure of IgG?
a) two copies of two polypeptide chains
b) multiple Ig domains
c) a β sandwich stabilized by a disulfide bridge
d) enables recognition of antigens with mM (i.e., 10-3 M) affinity
e) specific recognition by chemical complementarity
f) greater than 1200 amino acids
d) enables recognition of antigens with mM (i.e., 10-3 M) affinity
IgG molecules recognize their antigens
a) via hypervariable loops that occur only in the so-called constant domains.
b) by binding the antigen between the two sheets of a β sandwich of an Ig domain.
c) through complementary covalent interactions.
d) through hypervariable loops from both the heavy chain and the light chain.
e) through hypervariable loops that always have a Trp residue.
d) through hypervariable loops from both the heavy chain and the light chain.
The figure, taken from the assigned reading “Therapeutic Monoclonal Antibodies,” shows different types of antibody fragment molecules that have been designed for pharmaceutical use. Select the choice that accurately describes a fragment.
a) The BiTE fragment is one heavy chain from an IgG molecule.
b) The Fab comprises four variable domains.
c) The Fab comprises two light chains, each with one variable domain and one constant domain.
d) The scFv is a single-chain with two variable domains that bind epitopes with high-affinity.
d) The scFv is a single-chain with two variable domains that bind epitopes with high-affinity.
The choice that does not describe how drugs target enzymes to inhibit enzymatic activity.
a) destabilize enzyme structure
b) mimic enzyme substrates
c) mimic co-factors
d) induce a change in enzyme conformation
e) specific recognition
a) destabilize enzyme structure
Competitive inhibitors of an enzyme
a) change the apparent KM and don’t affect Vmax.
b) change the apparent Vmax but don’t affect KM.
c) change both the apparent KM and Vmax.
d) change the actual KM.
e) compete with other inhibitors.
a) change the apparent KM and don’t affect Vmax.
Darunavir is a potent drug against HIV infection in drug-experienced patients with potential for developing resistance because
a) Darunavir is a transition-state analogue.
b) HIV protease is a dimer with Asp residues in the active site.
c) Darunavir is a mechanism-based inhibitor.
d) Darunavir interacts with the polypeptide backbone and catalytic residues from each subunit.
e) Darunavir binds HIV protease with a very high affinity.
d) Darunavir interacts with the polypeptide backbone and catalytic residues from each subunit.
A transition-state inhibitor has high affinity for the targeted enzyme because
a) it mimics the putative transition state of the enzyme reaction.
b) it binds covalently.
c) it can cross the cell wall of a bacterium.
d) it alters Vmax.
e) it is water soluble.
a) it mimics the putative transition state of the enzyme reaction.
The basis for selectivity of certain NSAIDS, such as celecoxib, for COX-2 over COX-1 is
a) that the affinity of the drug is high and equal for COX-1 and COX-2.
b) because binding of the drug to COX-1 is too low to be measured.
c) because COX-1 and COX-2 have different tertiary structure.
d) the spatial complementarity between the inhibitor and COX-1 is poor.
e) because the drug is an irreversible inhibitor for COX-2 but not COX-1.
d) the spatial complementarity between the inhibitor and COX-1 is poor.
Statins interact with the active site of HMG-CoA reductase because
a) statins acetylate a serine near the active site of HMG-CoA reductase.
b) HMG-CoA reductase is the committed step in cholesterol biosynthesis.
c) statins react with NADPH.
d) a portion of the statin molecule resembles the mevalonate moiety of NADPH.
e) the statin molecule structurally resembles part of the substrate, HMG-CoA, but does not induce a conformational change in the enzyme.
e) the statin molecule structurally resembles part of the substrate, HMG-CoA, but does not induce a conformational change in the enzyme.
The development of an allosteric drug is attractive because
a) the binding site for an allosteric drug is likely to be highly conserved.
b) one can gain high affinity by mimicing the transition state of the enzyme target.
c) it is possible to consider activating an enzyme target in treating a disease.
d) binding an effector site with an allosteric drug would cause an induced fit of the enzyme.
e) it is competitive inhibition, which leads to high selectivity and reduces toxic side-effects.
c) it is possible to consider activating an enzyme target in treating a disease.
Many of the potential drug-drug interactions result from one cytochrome P450, CYP3A4. Which phrase does NOT accurately describe how CYP3A4 contributes to drug-drug interactions?
a) CYP3A4 levels can increase when a second drug induces expression of the P450 gene.
b) Multiple substrates compete for CYP3A4.
c) Plasma levels of a drug can increase when CYP3A4 is inhibited.
d) Plasma levels of a drug can decrease when CYP3A4 is inhibited.
e) The product from CYP3A4 metabolism of one drug interacts with a second drug and helps eliminate the second drug.
f) Some drugs depend on CYP3A4 for their therapeutic activity and proper dosing.
g) Antibiotics can bind to CYP3A4.
h) CYP3A4 forms an inhibitory complex with some drugs.
e) The product from CYP3A4 metabolism of one drug interacts with a second drug and helps eliminate the second drug.
In the structure of a cytochrome P450 shown below, a drug is most likely to bind at the position marked
a) 1
b) 2
c) 3
d) 4
e) 5
f) 6
c) 3
Many membrane transport proteins are targeted for inhibition by drugs, including
a) the sodium-glucose transporter
b) CYP3A4
c) the K+ channel
d) Na+/K+ ATPase
e) SERT and the sodium-glucose transporter
f) SERT
e) SERT and the sodium-glucose transporter
A type of transport system that maintains the Na+ and K+ gradients across the plasma membrane of cells
a) is a symport.
b) moves Na+ either to the inside or outside of a cell to retain the proper concentration gradient.
c) involves ATPase enzymatic activity.
d) has a cycle that is electrically neutral with respect to transporting Na+ and K+ across the membrane.
e) hydrolyzes the majority of ATP synthesized in cells independent of the movement of Na+ and K+.
c) involves ATPase enzymatic activity.
Which phrase is NOT an accurate description of cytochrome P450s?
a) P450s, along with membrane transporters, account for the adsorption and elimination of most drugs.
b) A large superfamily of enzymes that function in biosynthesis of eicosanoids and in detoxification of xenobiotics
c) P450s cannot function in isolation of other electron carrying proteins.
d) P450s are tethered to membranes of the endoplasmic reticulum.
e) The CYP2 and CYP3 families have fewer members than the CYP17 family.
e) The CYP2 and CYP3 families have fewer members than the CYP17 family.
