1. a. What is the pH of 100 mM HCl? b. What concentration of HCl will have a pH of 3.5? c. What is the pH of 100 mM acetic acid?

1. a. What is the pH of 100 mM HCl?b. What concentration of HCl will have a pH of 3.5?c. What is the pH of 100 mM acetic acid? (For acetic acid, pKa = 4.76)d. What concentration of acetic acid will have a pH of 3.5?2. a. What is the pH of 0.1 M H3PO4? (For H3PO4, pKa1 = 2.12, pKa2 = 7.21, pKa3 = 12.32)b. If equal parts of 0.1 M H3PO4 and 0.1 M NaOH are mixed, what will be the pH of the mixture?c. How many grams of NaOH (Mr 40) must be added to 100 ml of 0.1 M H3PO4 to create a phosphate buffer, pH 7.0?3. a. If 2 volumes of 0.1 M monobasic potassium phosphate, KH2PO4, are mixed with 1 volume of 0.1 M dibasic sodium phosphate, Na2HPO4, what will be the pH of the mixture?b. If 1 volume of 0.1 M KH2PO4 are mixed with 2 volumes of 0.1 M ethanolamine base, what will be the pH of the mixture? (For ethanolamine, pKa = 9.44)4. Complete hydrolysis of 25 mM ethyl acetate in an enzyme (i.e., esterase)-catalyzed reaction is carried out in a 40 mM NaCl solution buffered by 0.2 M Tris-Cl, pH 9.1. What is the pH at the end of the reaction? (For Tris base, which is the abbreviation for Tris (hydroxymethyl) aminomethane, pKa = 8.1; for acetic acid, pKa = 4.76)5. The equilibrium constant for the reaction of ADPβS and 1,3-diphosphoglycerate to give ATPβS and 3-phosphoglycerate is 400.a. What is delta G°´ for this reaction?Assume equal starting concentrations of ADPβS and 1,3-diphosphoglycerate to answer the following:b. What percent of each reactant will remain at equilibrium?c. What is the free energy change for the reaction after 10% of the reactants have been converted to products?d. What is the free energy change for the reaction after 50% of the reactants have been converted to products?e. Plot delta G´ as a function of the ratio of [ATPβS]/[ ADPβS] for the range 1/100 to 100/1. The plot may be done either manually or with a graphing program, and should be fully labeled.6. An amino acid binding protein involved in transport of the amino acid across membranes was isolated from E. coli. Equilibrium dialysis measurements at 25°C and 37°C yielded dissociation constant (Ks) values of 5.0 x 10-6 M and 2.0 x 10-5 M, respectively, for the protein-amino acid complex.a. What are the delta G°´ values for formation of this complex at 25°C and 37°C?b. What are delta H°´ and delta S°´ for this binding reaction assuming that they are constant over this temperature range?c. Is this amino acid binding driven by entropy or enthalpy? Explain.7. The hexapeptide N-acetyl-ala-arg-phosphoser-cys-met-glu has pKas of 1.6, 4.0, 4.2, 6.5, 8.1, and 12.1. (You will need to assign the pKas to particular groups.)a. If this hexapeptide is hydrolyzed by trypsin, what products will result?b. If these products are separated by DEAE-ion-exchange chromatography at pH 7.0, in what order will the products emerge from the column? Explain Why.8. a. If the hexapeptide in question 7 is dephosphorylated, then aminoethylated (AE) at cys, and cleaved by trypsin, what products will result?b. Which hydrolysis product would arrive first at the detector of a TOF mass spectrometer using electrospray ionization from an acidic solution to volatilize and charge the peptides? Explain why.9. Calculate the pI for the tripeptide D-C-Y and draw its predominant chemical structure at its pI, including the predominant + and – charges present. The N-terminal amino group has a pKa of 10.0 and the C-terminal carboxylic group a pKa of 3.4. Assume the pKas for the amino acid side chains are as given in Table 4.1 in the Garrett and Grisham text.10. ESI-TOF MS of a protein from a low pH solution generates a series of m/z peaks. The two most dominant successive peaks have m/z values of 964.3 and 1044.7.a. Calculate the molecular weight of the protein and the charges carried by the protein in these peaks (i.e., z values).b. How do these charges compare to the average number of charges a protein of this size would be expected to have at low pH. Explain.

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