23. The activity of chymotrypsin changes as the pH changes in the range of pH 5-9, as shown on the following graph. 100 Percent activity (%) gg 50 40 60 60 80 20 20 0 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 рН From your understanding of the chemical mechanism of the chymotrypsin reaction, and making the simplifying assumption that the only titratable groups are in the catalytic triad, explain the pH effect on chymotrypsin activity by answering parts a, b, and c. a. What amino acid functional group on which residue is most likely responsible for the effect of pH? b. What is the apparent pK₁ of that functional group? Indicate on the graph how you deduced the pKa. c. Briefly explain in terms of the chymotrypsin mechanism why the activity increases as the pH increases in this pH range.

80mL of a 0.3M solution of hexapeptide Leu-His-Cys-Glu-Asn-Arg is adjusted to pH=pI. The solution is then titrated with 0.2M HCL to a final pH of 2.1. Sketch the titration curve, labelling the pH and volume axes. Indicate the volume of HCL needed to reach relevant pKa value and equivalence point(s)z Relevant pKa values are: 2.1, 4.3, 6.0, 8.3, 9.8, and 12.5.

Quinine ( C20 H24 N2 O2) is the most important alkaloid derived from cinchona bark. It is used as an antimalarial drug. For quinine, pK, = 5.1 and pK, = 9.7 ( pKp = – log Kp). Only 1 g quinine will dissolve in 1920.0 mL of solution. Calculate the pH of a saturated aqueous solution of quinine. Consider only the reaction | Q+ H2O= QH+ + OH- described by pK, where Q = quinine. pH =

The hexapeptide Ala-Met-Leu-Lys-Phe-Asp is digested in the same tube with both Cyanogen Bromide and Trypsin at the same time at pH=7. Draw the structure of the product(s) that would bind to a cation exchange column. (Relevant pKa values are 2.2, 3.9, 9.5 and 10.5. Assume pKa values for any newly generated a-amino and a-carboxyl groups are 9.5 and 2.2 respectively)

Acetic acid is the principal ingredient in vinegar as shown; that's why it tastes sour. At equilibrium, a solution contains [CH3CO2H] = 0.0787 M and [H3 O+] = [CH3 CO2−] = 0.00118 M. What is the value of Ka for acetic acid?

80mL of a 0.3M solution of hexapeptide Leu-His-Cys-Glu-Asn-Arg is adjusted to pH=pl. The solution is then titrated with 0.2M HCI to a final pH of 2.1. Sketch the titration curve, labelling the pH and volume axes. Indicate the volume of HCl needed to reach each relevant pKa value and equivalence point(s). Relevant pka values are: 2.1, 4.3, 6.0, 8.3, 9.8, and 12.5.

The absorption of ketoconazole has been shown to be impaired in patients with drug-induced achlorhydria. The drug absorption was increased significantly to approximately 65% when the drug was taken with an acidic beverage such as Coca-Cola (pH 2.5). Ketoconazole is a synthetic azole antifungal agent and a weakly dibasic compound with pKa of 2.9 and 6.5. Using the information provided and the pH partition hypothesis, justify the use of Coca-Cola to improve the absorption of this antifungal agent.

Utilising the provided class data generate the following graphs: I) Michaelis Menten; II) Lineweaver-Burk; and III) Hanes-Woolf.  Ensure that you clearly label each graph,and add the relevant trendlines with equations. Table 1: Class data demonstrating the Absorbance at 700nm obtained for the alkaline phosphatase enzyme reaction Table 1 tube Abs700mm 1 0.000 2 0.060 2 0.090 4 0.140 5 0.190 6 0.250 7 0.290   The equipment we used are • 20mM Tris Buffer pH 8.5 • 33mM MgCl2 • Alkaline Phosphatase (2mg/ml) in 20mM Tris Buffer pH 8.5 • 4mM Glucose-1-phosphate • Acid Molybdate pH 5.0 • Reducing Agent • Distilled Water • Glass Test tubes • Tube Rack • Cuvette • Pipettes and Tips • Water bath set to 37oC  The method we used is  Method/Protocol: 1. Read the protocol in its entirety before starting. Take note of any additional information that appears in subsequent steps that may influence how previous steps are performed. 2. Using glass tubes, generate the reactions mixtures…

Draw dipeptide Arg-Thr at pH 6.0. Circle the six atoms that are restricted in one plane. Calculate its approximate pI assuming pKa for NH3+ is 10.0, pKa for COOH is 3.0, PKR for Arg is 12.0

The standard state free energy of hydrolysis of acetyl phosphate isΔG° = -42.3 kJ/mol. Acetyl-P + H2O acetate + Pi Calculate the free energy change for the acetyl phosphate hydrolysis in a solution of 2 mM acetate, 2 mM phosphate and 3 nM acetyl phosphate.