Question

Determine the primary structure of an octapeptide from the following data: acid-catalyzed hydrolysis gives 2 arg, leu, lys, met, phe, ser, and tyr. carboxypeptidase a releases ser. edman's reagent releases leu. treatment with cyanogen bromide forms two peptides with the following amino acid compositions: 1. arg, phe, ser 2. arg, leu, lys, met, tyr trypsin-catalyzed hydrolysis forms the following two amino acids and two peptides: 1. arg 2. ser 3. arg, met, phe 4. leu, lys, tyr

Answer 1

A Sentence that I Used:

The position of Met seems incorrect. The amino acid sequences of all proteins begin with Met because it is the amino acid that is attached to the anticodon for the AUG start codon. It looks like the student might have worked in a backward direction for transcription.

Answer 2

Complete Question

The complete question is shown on the first uploaded image

Answer:

The sequence of these amino acid would be

Lue Arg Lys Arg Met Phe Arg Ser

Step-by-step explanation:

The acid-catalyzed hydrolysis from makes us to understand that the polypeptides contains 8 amino acids

From the question we are told that the Edman's reagent releases Leu it means that the N-terminal amino acid would be Lue(i.e Leucine)

Also from the question we are told that the Carboxypeptidase released Ser this mean the the C-terminal amino acid would be Ser ( i.e Serine)

The Amino acids would in the polypeptides would be arranged like this

Lue __ __ __ __ __ __ Ser

Now from the question we are told that treatment with cranogen bromide form two peptides.

Now generally cranogen bromide divides a peptide on the C- side(i.e the extreme left side ) of Met(Methionine)(This is an amino acid obtained by hydrolysis of most common peptides )

So this means that any peptides containing Met(Methionine) must have Methionine as a C- terminal amino acid(i.e at extreme left) and for peptides that does not contain Met must be C - terminal peptides

From the question we see that it is the second peptide that contain Met and it is a penta peptide(i.e it contains 5 amino acid)

Thus the fifth amino acid is Met

So the sequence of these amino acid would now be

Lue __ __ __ Met __ __ Ser

From the question we are told that the the Trypsin-catalyzed hydrolysis forms two amino acid and two peptides

Now generally Trypsin divides a peptide on the C- side(i.e the extreme left) of Arg(Arginine) and Lys (lysine) and any peptide that holds Arg or Lys must have them as their C- terminal amino acids

From the first peptide in the two peptide formed we see that Arg would be the Seventh amino acid of the octapeptide because commonly the trypsin that sticks to the C-side of Arg would for Ser

and Phe would be the sixth amino acid of the octapeptide

So the sequence of these amino acid would be

Lue __ __ __ Met Phe Arg Ser

Looking at the first amino acid formed from the Trypsin-catalyzed hydrolysis we see that Arg would be the fourth amino acid of octapeptide as Trypsin divides a peptide on the C- side(i.e the extreme left) of Arg(Arginine).

From the second peptide of the Trypsin-catalyzed hydrolysis we see that Lys would be the third amino acid of the octapeptide as trypsin divides on the C- side of Lys (lysine) and Tyr would be the second amino acid of the octapeptide

So the sequence of these amino acid would be

Lue Arg Lys Arg Met Phe Arg Ser