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1. Tyrosine has pK, values of 2.2, 9.2 and 10.5. a. Draw the pH/structure number line: Show all of the structural protonated/deprotonated forms of tyrosine, indicate the net charge of each and the pH at which each species predominates. b. Most amino acids with a third pK, (for their R group) are categorized as a "charged" amino acid, such as His, Glu, Lys, Asp and Arg. Explain how tyrosine can have a third pK, not be classified as having a "charged" R group. c. Draw a titration curve for tyrosine, labeling the buffer regions and equivalence points

1. Tyrosine has pK, values of 2.2, 9.2 and 10.5. a. Draw the pH/structure number line: Show all of the structural protonated/deprotonated forms of tyrosine, indicate the net charge of each and the pH at which each species predominates. b. Most amino acids with a third pK, (for their R group) are categorized as a "charged" amino acid, such as His, Glu, Lys, Asp and Arg. Explain how tyrosine can have a third pK, not be classified as having a "charged" R group. c. Draw a titration curve for tyrosine, labeling the buffer regions and equivalence points

Biochemistry
Biochemistry
9th Edition
ISBN:9781319114671
Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
Chapter1: Biochemistry: An Evolving Science
Section: Chapter Questions
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Biochemistry I Chem 348 Problem Set #1: Titrations, Buffers, and pKa's 1. Tyrosine has pK, values of 2.2, 9.2 and 10.5. a. Draw the pH/structure number line: Show all of the structural protonated/deprotonated forms of tyrosine, indicate the net charge of each and the pH at which each species predominates. b. Most amino acids with a third pK, (for their R group) are categorized as a "charged" amino acid, such as His, Glu, Lys, Asp and Arg. Explain how tyrosine can have a third pK, not be classified as having a "charged" R group. c. Draw a titration curve for tyrosine, labeling the buffer regions and equivalence points d. circle the region on your titration curve where half the R groups are ionized. e. What is the isoelectric point for lysine? Indicate it on your titration curve with "pl" f. What is the approximate net charge of tyrosine at pH 7? 2. You wish to make 1 L of a 100 mM Phosphate buffer at pH=7.0. You have each of the forms of phosphate available: phosphoric acid (98 g/mol), monosodium phosphate (120 g/mol) and disodium hydrogen phosphate (142 g/mol). The pK, values for phosphate are 2.12, 7.21, 12.67). 3. Biomolecules come in all shapes and sizes and need to interact with one another,. Discuss the possible chemical properties of the exterior of a protein that favorably interact with the following molecules. What are the forces that are driving the interaction? a. A protein interacting with: a. OH H₂C-C-CH3 Ó–CH3 b. A protein interacting with the surface of a surface of a lipid bilayer, which is composed of hydrocarbons in the interior and charged, polar head groups on the exterior. c. A protein interacting with lipids (such as the inside of a membrane) 4. An enzyme catalyzed reaction was initiated in 1.0 mL of 0.06 M HEPES buffer, pH 7.55. During the course of the reaction 3.0 µmol of H" was produced. What was the final pH of the reaction mixture, assuming the enzyme and reaction metabolites other than H+ did not influence it? The pKa for HEPES is 7.55. b. What would the pH be in the absence of buffer (If the reaction occurred in water)?
Transcribed Image Text:Biochemistry I Chem 348 Problem Set #1: Titrations, Buffers, and pKa's 1. Tyrosine has pK, values of 2.2, 9.2 and 10.5. a. Draw the pH/structure number line: Show all of the structural protonated/deprotonated forms of tyrosine, indicate the net charge of each and the pH at which each species predominates. b. Most amino acids with a third pK, (for their R group) are categorized as a "charged" amino acid, such as His, Glu, Lys, Asp and Arg. Explain how tyrosine can have a third pK, not be classified as having a "charged" R group. c. Draw a titration curve for tyrosine, labeling the buffer regions and equivalence points d. circle the region on your titration curve where half the R groups are ionized. e. What is the isoelectric point for lysine? Indicate it on your titration curve with "pl" f. What is the approximate net charge of tyrosine at pH 7? 2. You wish to make 1 L of a 100 mM Phosphate buffer at pH=7.0. You have each of the forms of phosphate available: phosphoric acid (98 g/mol), monosodium phosphate (120 g/mol) and disodium hydrogen phosphate (142 g/mol). The pK, values for phosphate are 2.12, 7.21, 12.67). 3. Biomolecules come in all shapes and sizes and need to interact with one another,. Discuss the possible chemical properties of the exterior of a protein that favorably interact with the following molecules. What are the forces that are driving the interaction? a. A protein interacting with: a. OH H₂C-C-CH3 Ó–CH3 b. A protein interacting with the surface of a surface of a lipid bilayer, which is composed of hydrocarbons in the interior and charged, polar head groups on the exterior. c. A protein interacting with lipids (such as the inside of a membrane) 4. An enzyme catalyzed reaction was initiated in 1.0 mL of 0.06 M HEPES buffer, pH 7.55. During the course of the reaction 3.0 µmol of H" was produced. What was the final pH of the reaction mixture, assuming the enzyme and reaction metabolites other than H+ did not influence it? The pKa for HEPES is 7.55. b. What would the pH be in the absence of buffer (If the reaction occurred in water)?
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