e prog- ot? [H. De Voe and G. B. Kistiakowsky, J. Am. Chem. Soc. 83, 274 (1961)]. From these data, determine KM and Vmax for the reaction. ic reac- Carbon Dioxide Concentration (mmol L-¹) 1/Velocity (M1 sec) 1.25 36 × 103 models model member 2.5 20 × 103 5.0 12 × 103 20.0 6 × 103 for an tial dis- Ostrate? 32. Mathematical The enzyme ẞ-methylaspartase catalyzes the deamina- tion of B-methylaspartate no acid y. What f an en- me need nd that es in an y shown is com- on sub- Menten CH3 ☐ NH3 | OOC-CH-CH-COO¯ CH3 OOC-CH-CH2-COO + NH mesaconate absorbs at 240 nm [V. Williams and J. Selbin, J. Biol. Chem. 239, 1636 (1964)]. The rate of the reaction was determined by monitoring the absorbance of the product at 240 nm (A240). From the data in the following table, determine KM for the reaction. How does the method of calculation differ from that in Questions 30 and 31? Substrate Concentration (mmol L-¹) Velocity (AA240 min-1) haelis- display 0.002 0.005 0.020 0.040 0.060 0.080 0.100 0.045 0.115 0.285 0.380 0.460 0.475 0.505 tics on the yme? of this Vmax? Menten f Vmax), 33. Mathematical The hydrolysis of a phenylalanine-containing peptide is catalyzed by a-chymotrypsin with the following results. Calculate KM and Vmax for the reaction. Peptide Concentration (M) 2.5 × 10-4 5.0 X 10 10.0 101 4 -4 15.0 × 10-4 Velocity (M min-1) 2.2 × 10 6 5.8 × 10-6 5.9 X 10-6 7.1 X 10-6 e decar- btained rbonate 34. Mathematical For the Vmax obtained in Question 30, calculate the turnover number (catalytic rate constant) assuming that 1 × 10−4 mol of enzyme were used. 35. Mathematical You do an enzyme kinetic experiment and calculate a Vmax of 100 μmol of product per minute. If each assay used 0.1 mL of an enzyme solution that had a concentration of 0.2 mg/mL, what would be the turnover number if the enzyme had a molecular weight of 128,000 g/mol? 36. Reflect and Apply The enzyme D-amino acid oxidase has a very high turnover number because the D-amino acids are potentially toxic. The KM for the enzyme is in the range of 1 to 2 mM for the aro- matic amino acids and in the range of 15 to 20 mM for such amino acids as serine, alanine, and the acidic amino acids. Which of these amino acids are the preferred substrates for the enzyme? 37. Reflect and Apply Why is it useful to plot rate data for enzymatic reactions as a straight line rather than as a curve? 38. Reflect and Apply Under what conditions can we assume that KM indicates the binding affinity between substrate and enzyme?