Question

Gly – Ser – Cys – Glu – Asp – Asn – Cys – Arg |__________________| S S

1. Write the peptide sequence shown above using single letters and the full names of the amino acids.

2. Which amino acid is at N- terminus and which is at the C- terminus of the peptide?

3. What is the charge on the peptide at pH 4.5?

4. Name the peptide (using the amino acids in the sequence)

Answer 1

Q) Gly – Ser – Cys – Glu – Asp – Asn – Cys – Arg

I__________________| S S

1. Ans: Gly – Ser – Cys – Glu – Asp – Asn – Cys – Arg

G-S-C-E-D-N-C-R

Glycine-Serine-Cysteine-Glutamate-Aspartate-Asparagine-Cysteine-Arginine

2. Ans: N-terminus > G-S-C-E-D-N-C-R < C-terminus.

3. Ans: Positive (+) charge on the peptide at pH 4.5

  Gly – Ser – Cys – Glu – Asp – Asn – Cys – Arg

Isoelectric point(pI): 5.97 5.68 5.02 3.22 2.98 5.41   5.02 10.75

4: Oligopeptides.

Peptides of consisting less than 15 amino acids are known as oligopeptides.