1. After proper purification, the Edman reaction was used to sequence a dodecapeptide. The following data were obtained. The C-terminal amino acid is isoleucine; N-terminal amino acid is methionine; peptide fragments are Ala-Ala-Ile, Leu-Arg-Lys-Lys-Glu-Lys-Glu-Ala,  Met-Gly-Leu, and Met-Phe-Pro-Met. What is the sequence of this peptide?

Answer the following questions about the SWEETTEA peptide. Part A: How many peptide bonds are in this peptide? 7 Part B: What is the three letter code for the N-terminal amino acid? ser Part C: What is the three letter code for the C-terminal amino acid?

Part A: How many peptide bonds are in this peptide?

Part B: What is the three letter code for the N-terminal amino acid?

Part C: What is the three letter code for the C-terminal amino acid?

Amino acid analysis of a decapeptide revealed the presenceof:

Asp Glu Tyr Arg Met Pro Lys Ser Phe

The following facts were observed:

Carboxypeptidase A or B treatment of the decapeptide had anyeffect

Trypsin treatment yielded two tetrapeptides and free Lys

Clostripain treatment yielded a tetrapeptide and ahexapeptide.

Cyanogen bromide treatment yielded an octapeptide and adipeptide of sequence Asn and Pro.

Chymotripsin treatment yielded two tripeptides and atetrapeptide. The N terminal chymotryptic peptide had a charge of-1 at neutral pH and a net charge of -3 at pH=12.

One cycle of Edman degradation gave PTH-Ser.

What is the amino acid sequence?

Amino acid analysis of a decapeptide revealed the presenceof:

Asp Glu Tyr Arg Met Pro Lys Ser Phe

The following facts were observed:

Carboxypeptidase A or B treatment of the decapeptide had anyeffect

Trypsin treatment yielded two tetrapeptides and free Lys

Clostripain treatment yielded a tetrapeptide and ahexapeptide.

Cyanogen bromide treatment yielded an octapeptide and adipeptide of sequence Asn and Pro.

Chymotripsin treatment yielded two tripeptides and atetrapeptide. The N terminal chymotryptic peptide had a charge of-1 at neutral pH and a net charge of -3 at pH=12.

One cycle of Edman degradation gave PTH-Ser.

What is the amino acid sequence?

The following peptide fragments were generated after digestion of an 11 amino acid
polypeptide with trypsin and separately with thermolysin:
Trypsin: PA, YI, YKA, FDRH
Thermolysin: HYI, PAYK, AFDR
What is the sequence of the parent polypeptide?

Please show how you arrived at your answer!

(Note that trypsin recognizes the basic amino acids lysine (K) and arginine (R) and cleaves the peptide bond just after those; thermolysin recognizes the aromatic amino acids tyrosine (Y), phenylalanine (F), tryptophan (W), along with leucine (L), isoleucine (I), valine (V) and at high pH, histidine (H) and cleaves the peptide bond just in front of one of these.)