Q5. Each ionizable group of an amino acid can exist in one of two states, charged or neutral. Theelectric charge on the functional group is determined by the relationship between its pka andthe pH of the solution. This relationship is described by the Henderson-Hasselbalch equation.(a) Histidine has three ionizable functional groups. Write the equilibrium equations for its threeionizations and assign the proper pKa for each ionization. Draw the structure of histidinein each ionization state. What is the net charge on the histidine molecule in each ionizationstate?(b) Draw the structures of the predominant ionization state of histidine at pH 1, 4, 8, and 12.Note that the ionization state can be approximated by treating each ionizable groupindependently.(c) What is the net charge of histidine at pH 1, 4, 8, and 12? For each pH, will histidine migratetoward the anode (+) or cathode (-) when placed in an electric field?

Amino acids are simply an alpha-carbon bonded to 4 groups. The 4 groups are;an alpha-carboxyl group…

Answered: Q5. Each ionizable group of an amino…

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

Problem 1P

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What is the net average charge on the predominant form of lysine at pH values of (a) 2.0, (b) 5.0 and (c) 7.0? CLUE: draw the structure of lysine and show its different charged forms; then consider in which pH domains the pKa values for deprotonation/protonation occur.
A peptide has the sequence: Glu–His–Trp–Ser–Gly–Leu–Arg–Pro–Gly1. What would be the net charge of the molecule at pH a) 3, b) 8, and c) 11? (Use pKa values. Do not calculate the value per se, but instead estimate considering only fully protonated, or deprotonated states. Then estimate the pI for this peptide. Show full, clear and complete procedure
Each ionizable group of an amino acid can exist in one of two states, charged or neutral. The electric charge on the functional group is determined by the relationship between its pKa and the pH of the solution. This relationship is described by the Henderson-Hasselbalch equation. a Histidine has three ionizable functional groups. Complete the equilibrium equations by assigning the proper pK₁ for each ionization and the net charge on the histidine molecule in each ionization state. H || H₂N-C-C-OH | CH₂ 2 + HN -1 -NH pKa = 1.8 +2 || H₂N-C-C-0- 1 CH₂ + HN -NH pKa = 9.17 Answer Bank pK₂ = 7.59 H|| H₂N-C-C-0- | CH₂ N pKa -NH = 6.0 -2 н II H₂N-C-C-0- | CH₂ +1 N C -NH 0
Predict the direction of migration for the following amino acids in solutions of the specified pH. Write Isoelectric, if no migration occurs: Lys at pH=12 (pk values: 2.2; 9.2; 10.8) Glu at pH= 2.0 (pk values: 2.1; 9.5; 4.1) Leu at pH= 6.0 (pk vaues: 2.3; 9.7)
The addition of ethanol, CH3CHOH, t an aqueous solution lowers the surface tension of the solution. Predict whether adding ethanol to an aqueous protein solution will tend to stabilize or unfold the protein. Briefly explain.
Most protein dissolve in neutral salt solution, is that true? Provide reasoning
(E) Consider an amino acid that has one -amino group (pKa = 9.2), one -carboxyl group (pKa = 1.7) and one ionizable side chain (pKa = 6.2). At which pH range/s would this amino acid be effective as a buffer? If the amino acid shows a net charge of -1 at pH 11 and a net charge of +1 at pH 4, what pKa values would you use to calculate the isoelectric point? At what pH would the net charge be equal to zero?
Polymer beads (resin) made of DEAE (diethylaminoethyl) cellulose are packed in an ion exchange column. The total mass of beads in the column is 8.47 kg. On average, each bead weighs 0.0023 g and has an average of 18.4 * 10° positively charged amine groups that can adsorba negatively charged protein that passes through the column. A solution containing 2.07 mg/L of a protein is maintained at pH 6.3 and is passed through the ion exchange column at 0.215 L/min. The protein has a molecular weight of 154,000. The pk, of the amino groups on DEAE cellulose is 7.1, and the pl of the protein is 5.6. 2. A. How long can the column be operated before reaching 80% capacity (i.e., 80% of the amino groups on DEAE are bound to the protein through an ionic bond)? You may assume that one protein attaches to one + charge on the beads (although it's possible that proteins attach to more than one + charge). B. After reaching 80% capacity, explain what you would do to release the protein attached to the…
Which intermolecular forces are important in acetic acid, CH3 –(C=0)-oh? A particular amino acid contains a- CHNH3+ group. Is this amino acid more likely to be found on the inside or the outside of the folded protein? Briefly explain. The addition of ethanol, CH3CHOH, t an aqueous solution lowers the surface tension of the solution. Predict whether adding ethanol to an aqueous protein solution will tend to stabilize or unfold the protein. Briefly explain.
Given the following information about amino acid tyrosine answer questions 1 & 2: A. O H HO OH HO HO рказ 10.1 H NH₂ CH₂OH A. NH3 С. НО 1. Which of the above forms of tyrosine will be predominant in a solution with pH 9.5? 2. Which of the above forms of tyrosine is a cation? Answers to Questions 3 & 4 should be selected from the following choices: CH₂OH Holl O OH B. NH₂ pka2 9.01 conj acid OH В. НО "OH D. HO HO H OH pka1 2.2 O H -OH CH₂OH C. NH3 HO NH₂ O HO OH D. 3. Which of the monosaccharides above is a non-reducing sugar? 4. Which of the monosaccharides above is an aldotetrose? 5. What is the main functional group in a protein? ||||OH
What is the dissociation equilibrium constant of a protein if the concentration of free ligand is 3.0um when the fraction of bound sites is 0.6
a) Draw a non-covalent interaction between a water molecule and the charge on a phosphorylated serine residue(not including backbone atoms). What type of interactuon is this, how strong is it, and what holds the interaction together? b)Draw a non-covalent interaction between an alanine residue and a valine residue(not including backbone atoms). What type of interaction is this, how strong is it, and what holds the interaction together?

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