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
An octapeptide with the amino acids < Ile, Arg, Met, Phe,
Pro, Thr, Tyr, Val > was subjected to digestion reactions A, B
and C in order to deduce its amino acid sequence. The following
results were obtained. The exact position occupied by each of the
amino acids (positions 1-8 in the sequence) will be known when the
results are analyzed
A. Digestion with Trypsin yielded a [Thr-Arg] dipeptide and
a [hexapeptide] with the remaining amino acids.
Question (A1): Explain...
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