I need help with these questions. Please explain the reasoning and how do you ge
ID: 485584 • Letter: I
Question
I need help with these questions. Please explain the reasoning and how do you get the answer. Thank you
3. Consider the peptide P-A-R--S-F-R-A-N-C-E. After reacting this pure peptide with V8 protease, the products would be a. P-A-R-HS-F-R-A-N-C-E. b. P-A-R, -S-F-R, A-N-C-E. c. P-A-R-HS-F, R-A-N-C-E d. P-A, R-HS-F-R-A-N-C, E. 4. Following the last round of the Edman degradation, the R group of the phenyltiohydantoin was an imidazole. This means the amino acid at this point is: 5. The position of the amino acid in the question above was: a. In the middle. b. N-terminal. c. a branch point. d. C-terminal.Explanation / Answer
3. V8 protease is a class of Serine Protease, which is obtained from strain of Staphylococcus aureues, which is useful for cleaving the peptide bonds with Aspartic acid or Glutamic acid C-terminus. Aspartic acid is represented by D and Glutamic acid by E (D and E are one letter abbreviation for Amino acids).
In the above given peptide structure, you can see that the fourth option contains free Glutamic acid (E). Therefore (d) is the correct option.
4. The correct answer, again is (d). The reasons are as follows - (one letter abbreviation with their basic ring name )
P = Proline (cyclic ring non aromatic), Y = Tryrosine (Phenolic ring, aromatic), W = Tryptophan (Indole ring, Aromatic) and finally, H = Histidine (Imidazole ring). Thus imidazole ring is present in Histidine.
5. Generally, Edman degradation is used as sequencing method of amino acids in the given peptide. This is used to identify N-terminus of the peptide chain without disrupting the remaining part of the peptide. Therefore, the position of Histidine should be the N-terminus. The correct option is (b).