Interpretation:
The amino acid sequence of the polypeptides on the basis of partial acidic hydrolysis products of the peptide is to be given.
Concept introduction:
舧 Amino acids are organic compounds containing
舧 Amino acid composition analysis is a protein analysis method, which is widely used for the quantification of protein. The hydrolysis method involves random liberation of all amino acids of the substrate. The recovery of amino acid is done quantitatively using hydrolyzate. The peptide fragments are individually analyzed and the overall peptide sequence is ascertained on the basis of overlapping patterns of the peptide fragments.
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Organic Chemistry
- 22-35 Why is histidine considered a basic amino acid when the pKa of its side chain is 6.0?arrow_forward22-42 (a) How many atoms of the peptide bond lie in the same plane? (b) Which atoms are they?arrow_forward22-47 How many different tetrapeptides can be made (a) if the peptides contain the residues of asparagine, proline, serine, and metbionine and (b) if all 20 amino acids can be used?arrow_forward
- On complete hydrolysis, a polypeptide gives two alanine, one leucine, one methionine, one phenylalanine, and one valine residue. Partial hydrolysis gives the following fragments: Ala-Phe, Leu-Met, Val-Ala, Phe-Leu. It is known that the first amino acid in the sequence is valine and the last one is methionine. What is the complete sequence of amino acids?arrow_forward22-48 How many amino acid residues in the A chain of insulin are the same in insulin from humans, cattle (bovine), hogs, and sheep?arrow_forward22-61 Polyglutamic acid (a polypeptide chain made only of glutamic acid residues) has an a-helix conformation below pH 6.0 and a random-coil conformation above pH 6.0. What is the reason for this conformational change?arrow_forward
- 22-20 Show how alanine, in solution at its isoelectric point, acts as a buffer (write equations to show why the pH does not change much if we add an acid or a base).arrow_forward22-9 What is the difference in structure between tyrosine and phenylalanine?arrow_forwardFor the tripeptide GlyAlaCys a. What amino acid is located at the peptides N-terminal end? b. What amino acid is located at the peptides C-terminal end? c. How many peptide bonds are present? d. How many amide linkages are present?arrow_forward
- Glutathione (G-SH), one of the most common tripeptides in animals, plants, and bacteria, is a scavenger of oxidizing agents. In reacting with oxidizing agents, glutathione is converted to G-S-S-G. (a) Name the amino acids in this tripeptide. (b) What is unusual about the peptide bond formed by the N-terminal amino acid? (c) Write a balanced half-reaction for the reaction of two molecules of glutathione to form a disulfide bond. Is glutathione a biological oxidizing agent or a biological reducing agent? (d) Write a balanced equation for reaction of glutathione with molecular oxygen, O2 to form G-S-S-G and H2O. Is molecular oxygen oxidized or reduced in this process?arrow_forward22-31 A polypeptide chain is made of alternating valine and phenylalanine. Which part of the polypeptide is polar (hydrophilic)?arrow_forwardUsing both three- and one-letter codes for amino acids, write the structures of all possible peptides containing the following amino acids: (a) Val, Ser, Leu (b) Ser, Leu2, Proarrow_forward
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