[suhad91]

(((help please ))
You have isolated a decapeptide (a 10-residue peptide) called FP, which has anticancer activity. Determine the sequence of the peptide from the following information. (Note: commas are used to separate amino acids in a peptide fragment when the exact sequence is not known. Therefore, a list of amino acids in a fragment reflects amino acid composition or content rather than sequence.)

a) One cycle of Edman degradation of intact FP yields 2 mol of PTH-aspartate per mole of FP.

 b) Treatment of a solution of FP with 2-mercaptoethanol (a disulfide reducing agent) followed by the addition of trypsin yields three peptide fragments with the composition (Ala, Cys, Phe), (Arg, Asp), and (Asp, Cys, Gly, Met, Phe). The intact (Ala, Cys, Phe) peptide yields PTH-cysteine in the first cycle of Edman degradation.

 c) Treatment of 1 mol of intact FP with carboxypeptidase (which cleaves the C-terminal residue from peptides) yields 2 mol of phenylalanine.

d) Treatment of the intact pentapeptide fragment from part b (Asp, Cys, Gly, Met, Phe) with CNBr yields two peptides with the composition (Asp, Met) and (Cys, Gly, Phe). The (Cys, Gly, Phe) peptide fragment yields PTH-glycine in the first cycle of Edman degradation.

 

 

 

 

 

[Babcock_Hall]

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