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Question: A novel decapeptide is isolated from a fungus. The biotechnology
firm you work for gives you the …


A novel decapeptide is isolated from a fungus. The biotechnology
firm you work for gives you the following data and asks you to
determine the sequence so that more can be made by solid-phase
synthesis and sold as an antibiotic.

At each step below describe briefly what the reagents do, or
what information the technique gives, and interpretation of
results. State the obvious and tell what each reagent is used for
and what the data tells you!!!

Fresh samples are used for each of steps below:

1. The amino acid composition following acid hydrolysis of 1
nmole of the peptide gave the following results. Explain what this
technique does and What information you get from this data. Why
Asp? See Step 3.

Amino acid nmoles
Ala 0.92
Ser 0.63
Lys 0.97
Phe 0.88
Val 0.99
Asp 0.81
Pro 1.01
D-Leu 0.92
Tyr 0.89
Met 0.77

1.If you treat it with cyanogen bromide, you get 2 fragments.
The smaller piece is just Asn. Explain and Interpret. What does
CNBr do, etc? (2 pts.)

2. After treatment with chymotrypsin, you get only 2 fragments.
One fragment has the partial sequence Val-Lys-Ser-Phe-Pro-X-X. The
other piece was a tripeptide beginning with D-Leu. (again using
Edman sequencing with PITC). (3 pts.)

3. What is the sequence of the intact peptide? Show your work
and how you put all the data together to get your answer. (3
pts.)

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