Below are directions for determining a protein sequence. Submit your protein seq

Question

Below are directions for determining a protein sequence. Submit your protein sequence and you can earn additional credit up to 7 points added to your homework 2 score. Determine the sequence of a peptide consisting of 14 amino acids based on the following information: Amino acid composition (4S, 2L, F, G, I K, M, T, W, Y) N-terminal analysis (S) Carboxypeptidase digestion (L) Trypsin digestion (3S, 2L, F, I, M, T, W) (G, K, S, Y) Chymotrypsin digestion (F, I, S) (G, K, L) (L, S) (M, T) (S, W) (S, Y) N-terminal analysis of (F, Ir S) fragment from chymotrypsin digestion (S) Cyanogen bromide treatment (2S, F, G

Explanation / Answer

Carboxypeptidase is a protease enzyme that cleaves a peptide bond at carboxy terminal end of a polypeptide chain.

Hence "L" is present at terminal position.

N-terminal analysis --> S, i.e S is present at terminal position.

Hence the terminal aminoacids are S and L.

Trypsin digestion splits the polypeptide chain into 2 smaller polypeptides as given in the question.

The smaller part contains G, K, S, Y, where S will be at terminal position.

Since chymotripsin produces (S,Y), (G, K, L), (L, S), the proper sequence of the smaller part is (S, Y, G, K, L, S).

Since chymotripsin digestion produces (F, I, S) and N-terminal analysis of (F,I,S) results S at terminal position, the proper sequence now is (S, Y, G, K, L, S, I, F).

When cyanogen bromide reacts with methionine, it produces 'homoserine lactone.' Since homoserine lactone is at 10th position, methionine (M) is present at 10th position.

Also chymotripsin treatment produces (M,T).

Hence the proper sequence now becomes (S, Y, G, K, L, S, I, F, T, M (10th position)

Now 4 more remained to add to this sequence.

Out of the terminal aminoacids, S and L, S lies at the beginning. Hence L would lie at the end (14 th position).

Also chymotripsin treatment produces (L,S), the last two sequence will be (S,L).

Hence the proper sequence now becomes (S, Y, G, K, L, S, I, F, T, M, 11th, 12th, S, L)

chymotripsin treatment also produces (S, W).

Hence final proper sequence is (S, Y, G, K, L, S, I, F, T, M, S, W, S, L) (answer)

Related Questions

Navigate

• Browse (All)
• Browse B
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.