Each ionizable group of an amino acid can exist in one of two states, charged or neutral. The electric charge on the functionalgroup is determined by the relationship between its pKa and the pH of the solution. This relationship is described by theHenderson-Hasselbalch equation.aHistidine has three ionizable functional groups. Complete the equilibrium equations by assigning the proper pK₁ for eachionization and the net charge on the histidine molecule in each ionization state.H ||H₂N-C-C-OH|CH₂2+HN-1-NHpKa= 1.8+2||H₂N-C-C-0-1CH₂+HN-NHpKa = 9.17Answer BankpK₂ = 7.59H||H₂N-C-C-0-|CH₂NpKa-NH= 6.0-2н IIH₂N-C-C-0-|CH₂+1NC-NH0

If the pKa is low, the pH of the solution is less, and the acidity of the solution is high. i.e.,…

Answered: Each ionizable group of an amino acid…

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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Similar questions

Which of the twenty naturally occurring amino acid side chains are charged at a pan of 1.00? pH of 7.00? pH of 12.00? Make a table.
Phosphate buffers are commonly used to mimic biological systems. Given that phosophoric acid is a triprotic acid with three pKas (2.12, 7.21, and 12.32), why do you think this is? What are the dominant buffering compounds present in a phosphate buffer near physiological pH?
What average positive charge of an amino acid side chain with pKa 10.9 at a pH value of 11.9? Answer up to two decimals. (Please type answer no write by hend)
1.0.1 mL of a protein solution of concentration of 11 mg/mL was diluted to a total volume of 4.0 mL with water (i.e. 0.1 mL of the solution was added to 3.9 mL of water). 2 mL of this solution was then mixed with 18 mL of water. What is the concentration of the diluted protein solution? Space to show your workings:
A tetrameric protein dissociates into dimers when the detergent sodium dodecyl sulfate (SDS) is added to a solution of the protein. But the dimers are termed SDS-resistant because they do not further dissociate into monomers in the presence of the detergent. What intermolecular forces might be acting at the dimer-dimer interface? Are the intermolecular forces acting at the monomer-monomer interface different? Explain.
At which pH would the peptide with the amino acid sequence 'KEYHR' be found in an IPG (Immobilized pH gradient) strip after successful isoelectric focusing. Show calculation. lonizable groups Alpha amine group of K Side chain group of K Side chain group of E Side chain group of Y Side chain group of H Side chain group of R Alpha carboxylic acid group of R pka 8.95 10.53 4.25 10.07 6 12.48 2.17
The amino acid arginine ionizes according to the following scheme: (a) Calculate the isoelectric point of arginine. You can neglect contributions from form I. Why? (b) Calculate the average charge on arginine when pH = 9.20. (c) Is the value of average charge you calculated in part b reasonable, given the pI you calculated in part a? Explain your answer
After staining an SDS-PAGE gel with Coomassie Blue G-250, the protein bands are visualized by de-staining the gel in a Coomassie Blue G-250 de-staining solution. This solution is made up of 10% acetic acid, 50% methanol, and 40% distilled water. How much of each of these components do you need to prepare 5 liters of Coomassie Blue G-250 de-staining solution?
Glutamic acid (1one of the 20 amino acids) has a side- chain carboxyl group (COOH, pKa = 4.3) as shown in Figures 4.7 and 4.8 a. Write the chemical equation for the dissociation of the side chain COOH. Label the weak acid and the conjugate base. b. The Henderson-Hasselbalch Equation (shown below) can be used to determine the ionization status of a weak acid: pH = pKa + log [base] Use the Henderson Hasselbalch equation to determine whether the glutamic acid side chain [acid] • carboxyl group is protonated or deprotonated at physiological pH.
An enzyme uses a lysine and a histidine as general acid-base catalytic residues. In one direction of the reaction, the lysine and histidine residues are typically protonated (~NH3*, ~Im), but in the other direction of the reaction, the two residues are "reverse protonated" (~NH2, ~Hlm*) (see below scheme). A pH profile of the reaction at various pH values yielded estimates of 7.57 and 9.30 for the macroscopic ionization constants pk,' and pK2, respectively. A separate set of experiments with site-speciffic variants of the enzyme yielded an estimate of 8.78 for the microscopic ionization constant pKp. Given this information, what is the value of the microscopic ionization constant pKA? Report your answer to the nearest hundredth. Lys-NH3* His-HIm" KB H KA H* Lys-NH2 Lys-NH3* His-HIm" His-Im Kc H* Kp Lys-NH2 His-Im
A set of biomolecules listed in the table at right are in solution at pH 6.8, when they are passed through the multi-step separation process shown below. The sample passes through an ultrafilter with MWCO of 50,000 (assume this filter gives a perfect separation of molecules above and below the MWCO), and the retentate then flows through an ion exchange column filled with beads that have a positive charge under the operating conditions (pks = 7.3). Inlet Biomolecule Mixture pH 6.8 Ultrafiltration MWCO 50,000 Permeate Retentate lon Exchange Column Biomolecule Molecular weight pl A 68,000 4.2 B 92,600 9.6 C 144,000 A-3. Which biomolecules (A, B, C, etc.) exit the process in the permeate stream? K C-3. Which biomolecules are retained inside the ion exchange column? D E F G H B-3. Which biomolecules exit the process after passing through the ion exchange column? 5,800 68,000 Packed with DEAE cellulose beads, which have positively charged groups below a pH of 7.3 156,000 45,000 16,000 None…
The peptide aspartyl-glutamyl-leucyl-threonyl-alanine, shown in the sketch drawing window, has several ionizable groups. Adjust the charges to show the molecule as it would exist at pH 5.00. Use the pk values in the table below. pK, Values for Ionizable Groups of Amino Acids. Amino Acid pA, of a-COOH pA, of e-NH, pA, of Side Chain Isoelectric Point (pI) Alanine 235 9.87 6.11 Arginine 2.01 9.04 12.48 10.76 Asparagine 2.02 8.80 5.41 Aspartic acid 210 9.82 3.86 298 Cysteine 2.05 10.25 8.00 5.02 Glutzmic acid 2.10 9.47 4.07 3.08 Glutamine 217 9.13 5.65 Glycine 235 9.78 6.06 Histidine 7.11 9.18 6.10 7.64 Isoleucine 232 9.76 6.04 Leucine 233 9.74 6.04 Lysine 218 8.95 10.53 9.74 Methionine 2 28 9.21 5.74 Phenylalanine 2 58 9.24 5.91 Proline 2.00 10.60 6.30 Serine 221 9.15 5.68 Threonine 2.09 9.10 5.60 Trуptophan 238 9.39 5.88 Tyrosine 2 20 9.11 10.07 5.63 Valine 2 29 9.72 6.00 • Use the wedge hash bond tools to indicate stereochemistry where it exists. • If a group is 2chiral, do not use…

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