Another sample of the peptide is treated with trypsin, and a third sample is tre
ID: 738710 • Letter: A
Question
Another sample of the peptide is treated with trypsin, and a third sample is treated with chymotrypsin. The table below shows the fragments. Complete parts (a) and (b) below.Tryptic Fragments
Phe-Ser
Gly-Pro-Phe-Lys
Asn-Try-Ala-Val-Thr-Cys-Asp-Gln-Lys
Chymotrypic Fragments
Lys-Asn-Tyr
Ala-Val-Thr-Cys-Asp-Gly-Lys-Phe
Ser
Gly-Pro-Phe
a) Line up the fragments below so that fragments with the same sequences overlap. Drag each fragment to the appropriate location.
b) Write the sequence of the peptide.
Explanation / Answer
The sequence of the original peptide is: N'-Met-Val-Ser-Thr-Lys-Leu-Phe-Asn-Glu-ser-Arg-Val-Iele-Trp-Thr-Leu-Met-Ile-C' This sequence can be deduced by finding overlapping sequences in the fragments generated from the different digestions. Taking Met-as N terminal we have this fragment from digestion 1: Met-Val-Ser-Thr-Lys Another fragment from digestion 2 is: Met-Val-Ser-Thr-Lys-Leu-Phe ----------------------------- we have this fragment from digestion 1: Leu-Phe-Asn-Glu-Ser-Arg ---------------------------- Another fragment from digestion 2 is: Asn-Glu-Ser-Arg-Val-Ile-Trp ------------------------------ we have this fragment from digestion 1: Val-Ile-Trp-Thr-Leu-Met-Ile ---------------------------------- The overlapping sequences are highlighted in red.