Determine the sequence of amino acids in the peptide describ

Determine the sequence of amino acids in the peptide described below.

a. Hydrolysis of the peptide gives the following amino acids in equal amounts: Ala, Asp, Glu, Met, Lys, Phe, Tyr, and Val.

b. Treatment of the peptide with 2,4-dinitrofluorobenzene followed by hydrolysis yields Asp labeled with a 2,4-DNP group.

c. When the peptide is treated with carboxypeptidase, the concentration of Val increases rapidly.

d. Hydrolysis of the peptide with trypsin gives a tripeptide (A) and a pentapeptide (B).

e. The tripeptide (A) is cleaved by chymotrypsin to give Phe and a dipeptide with a pI of about 5.6.

f. The pentapeptide (B) is cleaved by chymotrypsin to give a dipeptide and a tripeptide. Reaction of the tripeptide with cyanogen bromide gives Tyr.

*There is another post with this exact same question, but I am lost when trying to figure it all out. If it helps, I have posted the URL to the identical question, please elaborate more and do not simply copy and paste that answer, thanks!*

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Solution

All reactions are from N to C terminal

Asp-Met-Tyr -4-Lys-Phe-7-Val

For 7^th and 4^th postion consider 4^th segment. The PI of 7^th-Val is 5.6. Valine has PI 5.96 and two aa Glu and Asp are remaining. So glutamine will present.

Now the peptide chain is Asp-Met-Tyr -Asp-Lys-Phe-Glu-Val