The amino acid sequence of human adrenocorticotropin, a
polypeptide hormone, is:
Ser-Tyr-Ser-Met-Glu-His-Glu-Arg-Trp-Gly-Lys-Pro-Val-Gly-Lys-Lys-Arg-Arg-Pro-Val-Lys-Val-Tyr-Pro-Asp-Ala-Gly-Glu-Asp-Gln-Ser-Ala-Glu-Ala-Glu-Pro-Leu-Glu-Phe
a)What is the approximate net charge of this molecule at pH 3? ph
7? ph 9? Assume that the pKs of the terminal -NH3+ and -COOH groups
are 7.8 and 3.6, respectively.
QUESTION 6 Which of the following peptides is most likely an
alpha helix?
Arg-Ala-Tyr-Pro-Met-Gly-Val-Leu-Ser-Asp
Glu-Ala-Tyr-Pro-Met-Gly-Val-Leu-Ser-Lys
Glu-Ala-Tyr-Phe-Met-Gln-Val-Leu-Ser-Lys
Arg-Ala-Tyr-Phe-Met-Gln-Val-Leu-Ser-Asp
Examine the following peptide then answer parts a-c
Lys-Asp-Pro-Leu-Trp-Ala-His-Met-Gln-Phe-Gly-Arg
a.estimate the net charge at pH 7
B.estimate the net charge at pH 12
which rptoleyic enzye would cleave this peptide into the most
fragments?
Asn-Met-Thr-Gln-Gly-Arg-Cys-Lys-Val-Asn-Thr-Phe-Val-His-Glu-Leu-Val-Asp-Val-Cys-Phe-Lys-Glu
A. Trypsin B.Chymotrypsin C.Thermolysint D.they would all given an
equal amou
Consider the following peptide:
Cys-Arg-Pro-Asp-Thr-Leu-His-Lys-Gln-Glu-His
How is the peptide different at pH = 6
and pH 8? Which of the two pHs would you use to run an ion exchange
column, and would you choose anion or cation exchange?
Determine which of these four peptides is most likely to become
a beta sheet.
Met-Leu-Lys-Ala-Ser-Ala-Leu-Glu-Lys-Leu-Ser-Glu
Ala-Glu-Met-Leu-Gln-Lys-Arg-Gly-Cys-Gly-Asp-Glu
Lys-Thr-Val-Ile-Trp-Pro-Phe-Tyr-Ile-Gln-Ile-Gly
Arg-Ser-Tyr-Glu-Gly-Leu-Lys-Arg-Ile-Ala-Glu-Ser
I would like help with the question but also I would like to
know what makes a peptide more likely to form a beta sheet over and
alpha helix and vice versa.
In the protein adenylate kinase, the C-terminal region is a
helical, with the sequence
Val-Asp-Asp-Val-Phe-Ser-Gln-Val-Cys-Thr-His-Leu-Asp-Thr-Leu-Lys.
a) Underline the hydrophobic amino acids in the sequence.
b) If you identified the correct amino acids you will notice
that there is a periodicity of hydrophobic amino acids. What is
this periodicity and why would this occur?
Propose (3) three qualitative chemical tests that can
differentiate the given peptides below:
Trp-Ala-Arg-Met-Ser (1)
Pro-Phe-Cys-Arg-Glu (2)
Support your choice of tests with brief explanation
Deduce the sequence of a heptapeptide that contains the amino acids Gly, His, Tyr, Ser, Ala, Met, and Arg, from the following experimental data. Edman degradation cleaves Ala from the heptapeptide, and carboxypeptidase forms His and a hexapeptide. Treatment of the heptapeptide with chymotrypsin forms a hexapeptide and a single amino acid. Treatment of the heptapeptide with trypsin forms a pentapeptide and a dipeptide. Partial hydrolysis forms His, Ala, Tyr, and the tripeptides Ser-Gly-Met and Gly-Met-Arg.
7 amino acids total
Look at this undecapeptide: Arg Asp Cys Glu Leu Lys Met
Phe NH4+. What would each step do to the udecapeptide?
Draw the final structure.
a. treatement with iodoacetate that had no
affect on the undecapeptide.
b. treatment with 2 x 2-mercaptoethanol
yielding a tripe-tide and octapeptide.
c. treatment with carboxypeptidase A liberated
leucine.
d. treatment with cyanogen bromide yielding a
methionine, a tripeptide and a heptapeptide.
The question states that these amino acids are only some
components of the...