Enzyme performance (a) Compare chymotrypsin, Muty, and carbonic anhydrase in terms of chemical difficulty. (Hint: compare kcat). (b) Which enzyme is faster? And by how much? (c) Draw a molecular sketch comparing TS stabilization strategies for Muty and chymotrypsin. (d) Compare chymotrypsin, Muty, and carbonic anhydrase in terms of how quickly they find their substrates. (Hint: compare kcat/KM). Which enzyme has the more "perfect" enzyme performance rating? (e) What is the molecular explanation for the apparently impossible fast rate at which Muty finds its substrate? (f) What is the biological constraint demanding this very high level of enzyme performance? Enzyme\Parameter Carbonic anhydrase Muty Chymotrypsin kcat (s-1) 600,000 0.2 100 KM (M) 0.008 1.2 x 10-10 0.005

3. (a) ( The equilibria for release of molecular dioxygen (O2) and protons (H+) by human hemo- globin (HbA) are illustrated in the scheme below in which the ionization (Ka, Ka') and ligand binding (K02, Ko2') are given as dissociation constants. The proton ionizations are known to be due to Hisẞ146 and account for a major part of the Bohr effect. A mutant hemoglobin is found for which Ka = 6.6 E-9 (pKa =8.18), Ka= 2.0 E-10 (pKa' = 9.70) and Ko2 = 1.0. What is the value of Ko2' for this mutant hemo- globin? K 02 = 1.0 Κα pka = 6.3 E-7 = 6.2 H*Hb O₂ H* + НЬ 02 HHb 02 Ka' = 2.0 E-8 pKa = 7.7 H+ + Hb + 02 K 02' = 0.032 (b) (' For the mutant hemoglobin described above, illustrate the relative changes that will be observed for the oxygen dissociation curve of Y versus pO2 compared to that of normal hemoglobin where Y represents thefraction of heme sites bound by O2. Explain whether there will be a change in the Bohr effect under physiological conditions, considering the pH of normal arterial…

3.18: An enzyme E binds a substrate S and a cofactor C. The equilibrium dissociation constantKd,S of the enzyme-substrate complex ES is 1 μM, for EC it is 10 μM. When the cofactor Cis present, K’d,S is decreased to 0.1 μM. What is the value for the dissociation constant K’d,C of the enzyme-cofactor complex in the presence of substrate S? Calculate the interactionenergy ΔΔGint for cofactor and substrate binding.

Calculate the rate enhancement for the enzyme pair: Enzyme 1: Kcat (sec-1)= 5.5 KM (µ M) = 1245 Kcat / KM = 0.00442 (µ M-1 sec-1)   Enzyme 2: Kcat (sec-1)= 3.2    KM (µ M) = 1785    Kcat / KM = 0.00179 (µ M-1 sec-1)

3. (a) The beakers below represent different conditions for measuring the initial velocity (vo) of an enzyme-catalyzed reaction under the steady-state approximation. The gray "donut-shaped" struc- tures represent the enzyme. The blue, filled circles represent free substrate molecules. The red cir- cles represent substrate molecules bound in the active site of the enzyme forming the Michaelis (ES) complex. Indicate in the diagram of the double reciprocal plot which kinetic parameters or variables each of the three "beaker conditions" represent either alone or in combination with another. A B 455 C V₁™¹ [So]-¹

B) Uncompetitive inhibition: Where do these inhibitors bind? To what mechanistic form of the enzyme do these inhibitors bind? What are changes to Km and Vmax?

am. 206.

Chemical scheme for enzyme catalysis (a) Write the chemical equations for enzyme,substrate, enzyme•substrate complex, and product as for a typical Michaelis-Mentenenzyme (b) At what condition is half of the enzyme expected to be saturated withsubstrate? (c) Plot the rate of product formation as a function of substrate concentration.(d) Indicate the KM parameter on your rate vs substrate plot.

5. Shown below are the first steps in the mechanism of a cysteine protease, which catalyses amide bond hydrolysis in a similar manner as serine proteases. (a) Complete this mechanisms, and (b) sketch the approximate reaction coordinate diagram for this catalyzed reaction relative to the uncatalyzed proteolysis. HN N HN cysteine protease

q41 please calculate the unknown concentration of the protein D wih an absorbance value of A412 given the standard curve indicated in the table. write your answers in numbers only with 2 decimals. protein concentration (ug/ml) absorbance 0 0.000 0.02 0.161 0.04 0.284 0.06 0.438 0.08 0.572 0.10 0.762