Question

Part A A decapeptide undergoes partial hydrolysis to give peptides whose amino acid compositions ares PTH-Val Whiat is the soquence of 1 lle, Phe 2. le, Arg Al 3 Arg lle 4 Ile, Ser 5 Phe, lle, 6 Glu. Val 7 Ser lio. Tre 8 His Arg Tre Ser hown Reaction of the intact decapeptide with Edman's reagent i the decapeptide?

I need help finding the sequence of this decapeptide, please provide explanation thank you

Answer 1

The N terminal amino acid is excised and separated as PTH derivative (phenylthiohydantoin derivative) in edman degradation method. therefore, val is the 1st aminoacid in the given decapeptide sequence. Hence, the compleate sequence are as follows:

Val-Glu-Phe-Ile-Ala-Arg-Ile-Ser-Tre-His

After val there is Glu as given in the 6th peptide, then you can see in 5th peptide only Glu is present, therefore after Glu either there will be Ile or Phe but when we see the peptide sequence 1 and 2, we get to know that after Glu there must be Phe then Ile-Ala- Arg. From the peptide sequence 4, 7 and 8, we reach to the conclusion there must be 2 Ile in the whole decapeptide sequence, hence, we get the decapeptide sequence i.e. Val-Glu-Phe-Ile-Ala-Arg-Ile-Ser-Tre-His.