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 pK and the pH of the solution. This relationship is described by theHenderson-Hasselbalch equation.Histidine 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.1-1-OHH₂N-C-C-OH1CH₂+HN-NHOH ||H₂N-C-C-0-|CH ₂HN-NHOOH ||H₂N-C-C-0-1CH₂-NH□HH₂N-C-C-0-LioCH ₂O-NH +2-2PK₁ = 1.8PK₁ = 7.59Answer BankpK₂ = 6.0+1-1PK₁ = 9.170

pKa is the pH at which half of the acid is dissociated. Given to us is the amino acid histidine with…

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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Assume a pH of 7.0 in aqueous solution. Please draw a tripeptide containing (in this order) a residue with a residue with an non-polar sidechain containing more than five carbons, a positively (+1) charged sidechain, and a residue with a polar (but not charged) sidechain with more than two carbons. Please give the names of the amino acid residues that you drew.
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
Draw the structural for the lipid glyceryl tristearate and draw a dotted line about the portion that makes it soluble in nonpolar solvents like cyclohexane. Format BIU ...
Would each of the following ions of serine exist at a pH above, below, or at its pI? Drag the appropriate items to their respective bins. Above pl H₂N-CH-COO CH₂OH H₂N-CH-COOH CH₂OH Below pl H₂N-CH-COO CH₂OH At its pl Reset Help
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 overall, net ionic charge on this peptide at pH = 7 would be: Cys - Ala - Glu-Arg - Met - Ser
Why do proteins have the net charge they have at low pH’s relative to high pH’s
You have a peptide that has the following amino acid sequence: GPMG Draw the structure of the polypeptide's most protonated form, and its charge. Then draw the structures of the increasingly deprotonated forms, along with their charges. Use the information from these structures to calculate the pl (isoelectric point) of the peptide using the pKa values provided in the table below. Write the pl as x.yz, for example, 7.62 or 3.09. Group Terminal a carboxyl group Aspartic acid Glutamic acid Histidine Terminal a-amino group Cysteine Lysine Tyrosine Arginine Acid EM 2-0" + H -N H H N-H H N-H T Base 1 1. تر H -5 H H O™ N-H Typical pK, 3.1 4.1 6.0 8.0 8.3 10.8 10.9 12.5
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…
"Potassium Bromate (KBr03) is added to flour as a softener that strengthens the texture of bread. It can do this by forming disulfide bonds between two cysteine amino acids in a reaction similar to the chemical equation given below. The function of KBr03 is to remove the 2 electrons needed to form the disulfide bond as shown in the figure below. Each of the cysteine amino acids will be in a protein chain, so the reaction binds the two chains together, giving the dough cohesion. However, potassium bromate is a proven carcinogen and is only allowed in foods in the United States because bakers will add the right amount and correct It has been assumed to meet the temperature and cooking time conditions. " KBRO, + C,H¸NO,SH → KBr + H,O+C,H„N,O,S, Balance the reaction of potassium bromate (KBr03) with the cysteine molecule (C3H6 NO2 SH) by converting it into the reduced step matrix using the additive matrix method. (Kis the symbol of potassium in the question) (Homogeneous linear equation…
Consider the following tripeptide:Gly—Ala—ValWhat is the charge of the primary structure of proteins at pH 1,5,10, and 12? Draw their structures (structural formulas) and predict their net charge.
Histidine is an amino acid containing an ionizable group in its side chain. This ionizable group has a pka of 6.0, meaning that His is in its deprotonated form at physiological pH (7.0-7.4). However, His is included in the positively charged amino acid category. Calculate the ratio of deprotonated/protonated His at pH 7.0, and use your answer to justify why this amino acid is included in the positively charged amino acid category. Show all work for full credit.

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