Draw the line bond structure for the general form of an amino acid using “R” to represent the side chain. Draw the N- and C- erminus groups using the forms that are predominant at physiological pH (pH = 7.4). Include lone pairs in your drawing. HINT: The structure of the predominant form of an amino acid will depend on the pH because amino acids involve the carboxyl group/carboxylate group conjugate pair and the quaternary ammonium group/amine group conjugate pair. Using the implications of the the Henderson-Hasselbalch relation, summarized in the table below, it is possible to predict the predominant form of these groups at a particular pH. Solution Condition pH pKa pH = pka Relative Amounts of Acid and Base Forms [HA] > [A-] [A-] > [HA] [HA] = [A-] The pK₂ values of amino acid carboxyl groups are between 2 and 5 (depending on which amino acid), therefore, at pH = 7.4, the base form (carboxylate ion) is predominant. Quaternary ammonium groups that are attached to the a-carbons of amino acids have pKą values of about 9.5, therefore, at pH = 7.4, the acid form (quaternary ammonium group) is predominant.

For the tripeptide ala-lys-phe a) Draw the structure of the peptide you would expect at pH 1. Show all lone pairs of electrons and show formal charges. Determine the charge on the tripeptide. b) Draw the structure of the peptide you would expect at pH 7. Show all lone pairs of electrons and show formal charges. Determine the charge on the tripeptide..

Match the following amino acids with their chemical properties H -N-CIC- A -A ✓ B но с D VE ✓ F ✓ G / CH3 CH3 CH B H но -N-C-C- feed C но -N-C-C- H CH₂ D HO -N-CIC- 1 H CH₂ OH E но ||| -N-C-C- II H CH₂ I CH₂ CH₂ CH₂ T NH3 I. Acidic II. Nonpolar III. Polar uncharged IV, Basic + F O HO -N-C-C- H CH₂ NH₂ G но | || -N-C-C- I H CH₂ 1

Draw the peptide bond between alanine and threonine. Include all linked atoms. Indicate a free‐electron pair on the nitrogen atom. Using arrows indicate how this electron pair delocalizes. Copy this image but depict the peptide bond as a double bond and a single bond for the carbonyl group. Remember to include any charges. Using arrows again indicate how the charge/electrons on the oxygen delocalizes. Indicate the dual nature of the peptide bond (resonance) by linking the two images by a double arrow.

Now let us look at a real amino acid, alanine. Fill in the chart below for each ionizable group. You need only the relationship discussed in the pdf posted and the numbers posted below. The next 6 questions will ask for the numbers you calculated for each of the letters below. pH when Average charge of group Group Ka pKa [A]/[HA] = 1 when pH = pK alpha-COOH ~10-2 A C alpha-NH3* ~10-9 В

Chemistry Write structure for oligopeptides “Boc-CPID-benzyl ester” and “Methy ester-CGLK-Boc”. Also show all the possible types of bonding between the two peptide chains.

Consider the hexapeptide S-H-I-R-M-P Draw the structure at pH 1.0. What is the charge at this point? Draw the structure at pH 7.4. What is the charge at this point? Determine the pl and draw its structure.

Draw the structure of the peptide WAKEP. Write the full name of each amino acid above the relevant R-group. Mark all of the peptide bonds on your drawing. Mark the charged groups on your drawing. Assuming that pH = 7, what is the Net Charge for the peptide? Type your numeric answer and submit -7 X You are incorrect

Researchers discover a new amino acid. Its R-group exclusively has hydrogen and carbon atoms. What behavior will this amino acid show? O Relative to the amino acids found in organisms, its interactions with water will be very high. It is hydrophilic. Relative to the amino acids found in organisms, its interactions with water will be intermediate. It is hydrophobic.

The amino acid histidine has ionizable groups with pK, values of 1.8, 6.0, and 9.2, as shown. COOH H₂N-CH CH, H pH = 1.29 COO H₂N-CH 1.8 CH pk, lonizable -COOH-COO- group Incorrect CH, H COO H₂N-CH 6.0 CH pk, CH, H H N CH -HisH¹-His COO H₂N-CH NH - NH, A biochemist makes up 85 mL of a 0.10 M solution of histidine at a pH of 5.5. She then adds 60 mL of 0.10 M HCI. What is the pH of the resulting solution? CH, H 9.2 C pk CH Macmillan Iraming T im be the [His IM.