Answer Happy

You notice that the samples you collected from the labs are now labeled 1, 2, and 3. You ask your lab assistants which samples correspond to which labs, but someone failed to label the tubes when running the assays. This is a disaster! Now, in addition to determining which sample (if any) matches the murder weapon, you will have to testify in court as a biochemist to convince a jury that the guilty sample (1, 2, or 3) belongs to the guilty person (Dr. Green, Wight, or Gray) based on what you know about enzyme kinetics. Are you up to the challenge? Who killed Dr. Bleu? The good news is that you may now go back to Hinesbiopharma and interview the three scientists about the molecular mechanism of the inhibitor that each has developed. Interview Dr. Gray Results: Dr. Gray is studying the effects of a transition-state analog. This molecule, which was developed by the company, is a fluorinated lactone called F-lac. F-lac mimics the geometry of the theoretical transition state in the XYZase reaction mechanism. Dr. Gray has solved crystal structures that confirm that F-lac binds noncovalently with the active site of XYZase. Dr. Gray also confirmed that F-lac freely dissociates from the enzyme. What type of enzyme inhibitor is Dr. Gray studying? O competitive O uncompetitive O noncompetitive O irreversible

Interview Dr. Greene Results: Dr. Greene is studying a compound that binds noncovalently to an allosteric site on the protein approximately 20Å away from the active site. She has solved crystal structures, which show that this allosteric site is blocked in the absence of substrate; a tryptophan residue blocks the ligand-binding pocket. When the enzyme binds the substrate, a shift in a helix connecting the active site and the allosteric site displaces the tryptophan side chain, clearing the pocket and allowing the inhibitor to bind. When the inhibitor is bound, it prevents a nearby loop from moving to associate with the remainder of the active site. The association of this loop with the active site is necessary for catalysis to occur. Binding studies have confirmed predictions made by the crystal structures: in the absence of substrate, the inhibitor binds with a K₁ of 10 mm, but in the presence of the substrate, the inhibitor K is decreased to 1 nM. How would Dr. Greene's inhibitor affect the apparent Km of the reaction catalyzed by XYZase? ( increase Ostay the same decrease

Interview Dr. Greene Results: Dr. Greene is studying a compound that binds noncovalently to an allosteric site on the protein approximately 20 Å away from the active site. She has solved crystal structures, which show that this allosteric site is blocked in the absence of substrate. A tryptophan residue blocks the ligand-binding pocket. When the enzyme binds the substrate, a shift in a helix connecting the active site and the allosteric site displaces the tryptophan side chain, clearing the pocket and allowing the inhibitor to bind. When the inhibitor is bound, it prevents a nearby loop from moving to associate with the remainder of the active site. The association of this loop with the active site is necessary for catalysis to occur. Binding studies have confirmed predictions made by the crystal structures: in the absence of substrate, the inhibitor binds with a K₁ of 10 mm, but in the presence of the substrate, the inhibitor Ka is decreased to 1 nM. How would Dr. Greene's inhibitor affect the apparent Vmax of the reaction catalyzed by XYZase? increase Ostay the same decrease

Interview Dr. Greene Results: Dr. Greene is studying a compound that binds noncovalently to an allosteric site on the protein approximately 20 Å away from the active site. She has solved crystal structures, which show that this allosteric site is blocked in the absence of substrate. A tryptophan residue blocks the ligand-binding pocket. When the enzyme binds the substrate, a shift in a helix connecting the active site and the allosteric site displaces the tryptophan side chain, clearing the pocket and allowing the inhibitor to bind. When the inhibitor is bound, it prevents a nearby loop from moving to associate with the remainder of the active site. The association of this loop with the active site is necessary for catalysis to occur. Binding studies have confirmed predictions made by the crystal structures: in the absence of substrate, the inhibitor binds with a Ka of 10 mM, but in the presence of the substrate, the inhibitor Ka is decreased to 1 nM. What type of enzyme inhibitor is Dr. Greene studying? O competitive O uncompetitive O noncompetitive O irreversible