Problem 3
Catalase breaks down hydrogen peroxide about \(10^{7}\) times faster than the uncatalyzed reaction. If the latter required one year, how much time would be needed by the catalasecatalyzed reaction?
Problem 4
Give two reasons why enzyme catalysts are \(10^{3}\) to \(10^{5}\) more effective than reactions that are catalyzed by, for example, simple \(\mathrm{H}^{+}\) or \(\mathrm{OH}^{-}\).
Problem 5
For the reaction of glucose with oxygen to produce carbon dioxide and water, Glucose \(+6 \mathrm{O}_{2} \rightarrow 6 \mathrm{CO}_{2}+6 \mathrm{H}_{2} \mathrm{O}\) the \(\Delta G^{\circ}\) is \(-2880 \mathrm{kJ} \mathrm{mol}^{-1}\), a strongly exergonic reaction. However, a sample of glucose can be maintained indefinitely in an oxygencontaining atmosphere. Reconcile these two statements.
Problem 7
Suggest a reason why heating a solution containing an enzyme markedly decreases its activity. Why is the decrease of activity frequently much less when the solution contains high concentrations of the substrate?
Problem 9
Does the presence of a catalyst alter the standard free energy change of a chemical reaction?
Problem 10
What effect does a catalyst have on the activation energy of a reaction?
Problem 13
For the hypothetical reaction \(3 A+2 B \rightarrow 2 C+3 D\) the rate was experimentally determined to be Rate \(=k[\mathrm{A}]^{1}[\mathrm{B}]^{1}\) What is the order of the reaction with respect to A? With respect to B? What is the overall order of the reaction? Suggest how many molecules each of \(\mathrm{A}\) and \(\mathrm{B}\) are likely to be involved in the detailed mechanism of the reaction.
Problem 17
Distinguish between the lock-and-key and induced-fit models for binding of a substrate to an enzyme.
Problem 21
If only a few of the amino acid residues of an enzyme are involved in its catalytic activity, why does the enzyme need such a large number of amino acids?
Problem 25
For an enzyme that displays Michaelis-Menten kinetics, what is the reaction velocity, \(\left.V \text { (as a percentage of } V_{\max }\right)\), observed at the following values? (a) \([\mathrm{S}]=K_{\mathrm{M}}\) (b) \([\mathrm{S}]=0.5 K_{\mathrm{M}}\) (c) \([\mathrm{S}]=0.1 K_{\mathrm{M}}\) (d) \([\mathrm{S}]=2 K_{\mathrm{M}}\) \((\mathrm{e})[\mathrm{S}]=10 K_{\mathrm{Y}}\)
