Determine the amino acid sequence of the following oligopeptide. Please note tha

Question

Determine the amino acid sequence of the following oligopeptide. Please note that the order of amino acids given in parentheses is alphabetical, and does not reflect the order in the peptide. Amino acid analysis following complete hydrolysis in 6M HCl gives the following composition: (Ala, Arg, Asx, Cys, 2Glx, His, lie, Leu, Lys, 2Met, Phe, Tyr and NH4+) The first amino acid released upon treatment of the peptide with aminopeptidase is cysteine. Treatment of the peptide with cyanogen bromide yields fragments of the following compositions: Treatment of the peptide with trypsin yields the fragments of the following compositions: Treatment of the peptide with chymotrypsin yields free alanine and fragments of the following compositions: Treatment of the peptide with V8 endopeptidase yields fragments of the following compositions:

Explanation / Answer

answer=

H2N-Cys-Leu-Met-Ile-Lys-Phe-GLx-Glx-Arg-His-Met-AsX-Tyr-Ala-COOH

1)With amino peptidase, N-terminal amino acid cleaved,-H2N-Cys-

2) With CNBr, carboxyl side of methionine cleaved=-AsX-Tyr-Ala

Ile-Lys-Phe-GLx-Glx-Arg-His-Met

Cys-Leu-Met are the three fragmants

3)Trypsin enzyme cleaves carboxyl side of basic amino acids-eg Lys,Arg,His

-His-Met-AsX-Tyr-Ala

-Phe-GLx-Glx-Arg -NH4+(side chain of Arg)

-Cys-Leu-Met-Ile-Lys

4)Chymotrypsin cleaves carboxyl side of aryl amino acids like PHe,tyr,trp

free Ala-COOH

-GLx-Glx-Arg-His-Met-AsX (NH4+ of arg)

5)V8 cleaves only AsX and GlX internal n-terminal of peptides

Cys-Leu-Met-Ile-Lys-Phe-GLx

Glx-Arg-His-Met-AsX-Tyr-Ala- and (NH4+ of arg)

)

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