The following amino acid is dissolved in solution at pH 7.4.HCH'+ CHCH₂H/H+HCa. Which amino acid is this? (all lower case)N-HCHCH₂b. What is the pKa of its ionizable side chain? (Use the value from the textbook.)c. What is the ratio of the uncharged to the charged form at pH 7.4? (write answer asnumber with one decimal place, ex 2.5 or 0.2 or 50.0 with an implicit "to 1")

Dissociation of a weak acid is mathematically described by the Henderson-Hasselbalch equation:pH =…

Answered: The following amino acid is dissolved…

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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Biotin (below), also known as Vitamin B7, is a very large organic compound derived primarily from meats, eggs, nuts, and certain vegetables. The pKa of biotin is 4.4. This means that biotin is/is not soluble at the pH of stomach acid (pH ~2.5) and is/is not soluble at the pH of duodenum (pH ~6.1). a is soluble in stomach and duodenum b is soluble in stomach but not duodenum c is not soluble in either stomach or duodenum d is not soluble in stomach but is soluble in duodenum
The amino acid glycine is often used as the main ingredient of a bufferin biochemical experiments. The amino group of glycine, which has apKa of 9.6, can exist either in the protonated form. (a) In what pH range can glycine be used as an effective buffer due to itsamino group?(b) When 99% of the glycine is in its protonated form, what is the numerical relation between the pH of the solution and the pKa of the amino group?
Amino acid Cys has ionizable groups with pKa values 2.0, 8.0, and 10.0. Determine the charge on the Cys at the following pH. Be sure to write the charge in fraction with sign in front (for example, +1/2, -1/5, and +7/8). Charge when pH is at 1.0? _________ Charge when pH is at 9.0? _________ Charge when pH is at 8.0? _________ Charge when pH is at 10.0? _________
A 100 ml solution of 0.1 M amino acid (AA) at ph 1.0 was titrated with NaOH solution. The pH was monitored, and the results were plotted on the graph. The keypoints in the titration are designated I to VII. What is the possible identity of the amino acid? What is the isoelectric point of AA? what is the pKa corresponding to the dissociation of the alpha carboxylic group? Region/point where AA is predominantly present as a (-1) charged species? The effective buffering range for the amino acid in the acidic region? Region/point where the solution has 50:50 percent mixture of the (0) and (-1) species
The amino acid glycine is often used as an ingredient in buffers for biochemistry experiments. The amino group of glycine has a pKa of 9.6. Glycine exists in either a protonated form (-NH3+) or a free base (-NH₂). a) In what pH range can glycine be used as an effective buffer? b) In a 0.1M solution of glycine at pH 9.0, what fraction has its amino group in the protonated form? c) When 99% of the glycine is in the protonated from, what is the numerical relation between the pH of the solution and the pKa of the amino group?
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. Write the equilibrium equations for its three ionizations and assign the proper pKafor each ionization. Draw the structure of histidine in each ionization state. What is the net charge on the histidine molecule in each ionization state?(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 group independently.(c) What is the net charge of histidine at pH 1, 4, 8, and 12? For each pH, will histidine migrate toward the anode (+) or cathode (−) when placed in an electric field?
If your initial absorbance from undiluted crude dialysate is 4.50, determine the fold dilution needed to yield an absorbance of approximately 0.700. If you want to prepare 1.0 ml of diluted crude, what volume (mL) of crude dialysate must you add? Your Answer: Answer units It is possible to estimate the molar extinction coefficient of a protein from knowledge of its amino acid composition, as shown from your experiences with EXPASY. From the molar extinction coefficient of tyrosine, tryptophan and cystine (cysteine does not absorb appreciably at wavelengths >260 nm, while cystine does) at a given wavelength, the extinction coefficient of the native protein in water can be computed using the following equation: e(Protein) = #(Tyr)*E(Tyr) + #(Trp)*E(Trp) + #(Cystine)*E(Cystine) Where (if A280 measured in water): E (Tyr) = 1490, ɛ (Trp) = 5500, e (Cystine) = 125 Estimate the molar extinction coefficient of lysozyme using the above equation and the amino acid composition data you found…
Given the following peptides below, what would be more soluble at the indicated pH? 1. (Gly)20 or (Glu)20 in pH 7.0 2. (Lys-Ala)3 or (Phe-Met)3 in pH 7.0 3. (Gly)20 or (Glu)20 in pH 6.0|| 4. (Ala-Ser-Gly)s or (Asn-Ser-His)s in pH 6.0 5. (Ala-Asp-Gly)8 or (Asn-Ser-His)8 in pH 3.0
Diethylaminoethyl cellulose is a positively charged resin used in ion-exchange chromatography with a pKa is about 11. A negatively charged protein with an isoelectric point of 5.0 is applied to the column in a buffer at pH 7 and containing 0.1 M NaCl. Which of the following conditions is most likely to weaken the interaction between the protein and the resin? A Raising the pH to 8 and decreasing the NaCl to 0.05 M B Raising the pH to 8 and increasing the NaCl to 0.2 M C Lowering the pH to 6 and decreasing the NaCl to 0.05 M D Lowering the pH to 6 and increasing the NaCl to 0.2 M
Consider a protein in which a negatively charged glutamic acid side chain (pKa=4.2) makes a salt bridge (ion-ion interaction) with a positively charged histidine side chain (pKa=6.5). Part C: Justify your answer with calculations of partial charges on these amino acid side chains at pH=7.9.(Hint: Consider lessons from Coulomb's law, and the Henderson-Hasselbalch equation.)
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.
Determine the net charge on the following pentapeptide "Lys-Ala-His-Asp-Ser" at: a. pH 1.0 b. pH 10.1

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