Chapter 8 Enzymes:Basic Concepts and Kinetics 3 8 Allosteric enzymes can be identified because the plot of initial velocity,Vo,versus substrate concentration,S,is not hyperbolic but -shaped. Ans:sigmoidal Section:8.4 9A inhibitor has a structure similar to the substrate and reversibly binds to the active site of the enzyme. Ans:competitive Section:8.5 10 The straight-line kinetic plot of 1/Vo versus 1/S is called a Ans:Lineweaver-Burk plot,or double reciprocal plot Section:8.4 Multiple Choice Questions 1 What is the common strategy by which catalysis occurs? A)increasing the probability of product formation B) shifting the reaction equilibrium C) stabilization of transition state D) All of the above. E) None of the above. Ans:C Section:8.3 and Introduction 2 What conclusion can be drawn concerning an inhibitor if the Vmax is the same in the presence and absence of the inhibitor? A)The inhibitor binds to the substrate. B) The inhibitor has a structure that is not very similar to the substrate. C) The inhibitor reacts with a critical residue of the enzyme. D)The inhibitor binds to the same active site as the substrate. E)The KM is smaller in the presence of inhibitor. Ans:B Section:8.5 3 Examples of cofactors include A) Zn+2,Mg*2,and Ni+2. B) biotin and thiamine pyrophosphate. C) pyridoxal phosphate and coenzyme A. D) b and c. E)a,b,and c. Ans:E Section:8.1 4 The formulaK0 indicates the relationship between A)the free energy and the equilibrium constant. B)the reaction equilibrium and the isomerization rate. C)the equilibrium constant and standard free energy. D)All of the above. E)None of the above. Ans:C Section:8.2Chapter 8 Enzymes: Basic Concepts and Kinetics 3 8 Allosteric enzymes can be identified because the plot of initial velocity, V0, versus substrate concentration, S, is not hyperbolic but __________________ -shaped. Ans: sigmoidal Section: 8.4 9 A __________________ inhibitor has a structure similar to the substrate and reversibly binds to the active site of the enzyme. Ans: competitive Section: 8.5 10 The straight-line kinetic plot of 1/ V0 versus 1/S is called a ________________________. Ans: Lineweaver-Burk plot, or double reciprocal plot Section: 8.4 Multiple Choice Questions 1 What is the common strategy by which catalysis occurs? A) increasing the probability of product formation B) shifting the reaction equilibrium C) stabilization of transition state D) All of the above. E) None of the above. Ans: C Section: 8.3 and Introduction 2 What conclusion can be drawn concerning an inhibitor if the Vmax is the same in the presence and absence of the inhibitor? A) The inhibitor binds to the substrate. B) The inhibitor has a structure that is not very similar to the substrate. C) The inhibitor reacts with a critical residue of the enzyme. D) The inhibitor binds to the same active site as the substrate. E) The KM is smaller in the presence of inhibitor. Ans: B Section: 8.5 3 Examples of cofactors include A) Zn +2 , Mg +2 , and Ni+2 . B) biotin and thiamine pyrophosphate. C) pyridoxal phosphate and coenzyme A. D) b and c. E) a, b, and c. Ans: E Section: 8.1 4 The formula K'eq = 10 G/1.36 indicates the relationship between A) the free energy and the equilibrium constant. B) the reaction equilibrium and the isomerization rate. C) the equilibrium constant and standard free energy. D) All of the above. E) None of the above. Ans: C Section: 8.2