Question

Find out the sequence of amino acids from N-terminal to C-terminal in given polypeptide chain. 

 

• A. Thr-Ser-Asp-Gly-Ala
• B. Ser-Thr-Asp-Gly-Ala
• C. Ser-Asp-Thr-Gly-Ala
• D. Thr-Ser-Asp-Gly-Ala

Hint:

Peptide sequences are always read from the N-terminal (free amino group) to the C-terminal (free carboxyl group).

Answer 1

The Correct Option is A

To determine the sequence of amino acids in a polypeptide chain from the N-terminal to the C-terminal, we must examine the provided polypeptide sequence and identify each amino acid in order.

A polypeptide chain starts with the N-terminal (amino terminal) and ends with the C-terminal (carboxyl terminal). In a chemical structure diagram of a polypeptide, the N-terminal is typically on the left side and the C-terminal is on the right side.

Let’s annotate the given sequence, examining the image provided (here we represent it in writing due to limitations):

• The first amino acid at the N-terminal is Threonine (Thr).
• The second amino acid is Serine (Ser).
• The third amino acid is Aspartic acid (Asp).
• The fourth amino acid is Glycine (Gly).
• The fifth amino acid at the C-terminal is Alanine (Ala).

Thus, the sequence of amino acids from the N-terminal to the C-terminal is: Thr-Ser-Asp-Gly-Ala.

Let us analyze the options provided:

• Option 1: Thr-Ser-Asp-Gly-Ala (Correct)
• Option 2: Ser-Thr-Asp-Gly-Ala
• Option 3: Ser-Asp-Thr-Gly-Ala
• Option 4: Thr-Ser-Asp-Gly-Ala (Duplicate Option)

The correct option is clearly the first one listed as Option 1: Thr-Ser-Asp-Gly-Ala. It matches exactly the sequence from the image.