A protein has the amino acid sequence Asp-Ser-Arg-Leu-Ser-Lys-Thr-Met-Tyr-Ser-Ile-Glu-Ala-Pro-Ala-Lys-Leu-Asp-Trp-Glu-Gln-Asn-Met-Ala-Leu Asp-Ser-Arg-Leu-Ser-Lys-Thr-Met-Tyr-Ser-Ile-Glu-Ala-Pro-Ala-Lys-Leu-Asp-Trp-Glu-Gln-Asn-Met-Ala-Leu How many peptide fragments would result from cleaving the sequence with each of the given reagents?

Answer :

The given question is incomplete. The complete question is as follows:

A protein has the amino acid sequence:

Asp-Ser-Arg-Leu-Ser-Lys-Thr-Met-Tyr-Ser-Ile-Glu-Ala-Pro-Ala-Lys-Leu-Asp-Trp-Glu-Gln-Asn-Met-Ala-Leu

How many peptide fragments would result from cleaving the sequence with…

a)cyanogen bromide=_______

b)trypsin=________

c) chymotrypsin=________

Answer:

Different enzymes and chemical conditions are require to hydrolyze the proteins into small peptides and amino acid sequences.

a) The cyanogen bromide can cut only at C terminus end of the methionine residues. The cynogen bromide will cleave at Thr-Met-Tyr and Asn-Met-Ala-. This results in the generation of three fragments.

b) Trypsin enzyme cleaves the lysine and arginine residue of the peptide chain and should not be followed by proline. Lysine will cleave at  Ser-Lys-Thr, Ser-Arg-Leu, and Ala-Lys-Leu. This result in the generation of four fragments.

c) Chymotrypsin cleaves at the carboxy side of aromatic amino acid residues ( phenylalanine, tyrosine, tryptophan) and leucine. This will cut at the Arg-Leu-Ser, Met-Tyr-Ser, Lys-Leu and Asp-Trp-Glu and results in the generation of five fragments.

Answer: A

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