1.
2. (10 pts) What is the sequence of the following HEXAPEPTIDE? *PROVIDE
WORK/ANSWER for B-F! Observations from Sequencing Experiments: A. Amino acid content:
Y, R, M, K, G, D B. Reaction with 1-fluoro-2,4-dinitrobenzene yielded DNP-G. C. Treatment
with chymotrypsin yielded two tripeptides D. Treatment with trypsin yielded three dipeptides. E.
Treatment with carboxypeptidase yielded methionine. F. N-terminal sequencing of one of the
chymotrypsin-produced tripeptides yielded DNP-K Explanation and summary of protein
sequencing techniques 1-fluoro-2,4, dinitrobenzene (DNFB) is used to identify N-terminal amino
acid of a peptide, and provides the following product: DNP-AA (where AA- the N-terminal
amino acid of the peptide) Trypsin is an enzyme that cleaves a peptide at the C-terminal side of
R and K. Chymotrypsin is an enzyme that cleaves a peptide at the C-terminal side of F, Y and
Ww. Carboxypeptidase is an enzyme that cleaves off the C-terminal amino acid of any peptide. .
Solution
Th eamino acids are : Y, R, M, K, G and D
1-fluoro-2,4- dinitrobenzene (FDNB) produces DNP-G. FDNB separates tge N- terminal amino
acid from a peptide. SO, in this peptide, the N- terminal amini acid is G.
Carboxypeptidase methionine ( M). Carboxypeptidase cleaves the C- terminal amino acid. SO,
here the C- terminal amino acid is M.
The sequence would be : G - _ -_ -_ -_ - M
Chymotripsin yields two tripeptides. Chymotripsin cleaves a peptide at the C- terminal end of F,
Y and K. Here in the sequence Y is present. So , the sequence would be :G - _ -Y -_ -_ - M
The N- terminal sequencing of the chymotripsin derived tripeptides yield DNP- K. So, K will be
just after Y in the sequence: G - _ -Y - K -_ - M
Trypsin yield three dipeptides and trypsin cleaves a peptide from the C- side of R and K. So, the
complete sequence is:
G - R -Y - K -D - M
The tripeptides derived by chymotripsin treatment are: G-R-Y and K-D-M

2.
The dipeptides derived by trypsin treatment are: G-R , Y-K and D-M.