What is the pI for Lys-Glu-Ser?

Expert Solution

Lys-Glu-Ser peptide is which can be represented as ,simply

Now, the cationic and/or anionic forms of Lys-Glu-Ser upon pH changing are given as

Hence, from the above pH values we can determine the pK_a s of the corresponding functional groups as followsFrom the definition of the isoelectric point we know that

where, pK₁ and pK₂ are the pK_a values of the monocation and monoanion form and from the above pH diagram it is clear that if we consider the overall neutral form which is created via step-B from monocation and destroyed via step-C to monoanion. So, the two pK_a s that we are looking for are the pK_a of the terminal NH₂ ie. 8.5 and the the pKa of the branched COOH ie. 3.5. So, from the formula we can calculate the Pⁱ of the peptide

queen_honey_blossom answered 2 years ago

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 appr

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.

Given the following sequence asp-cys-met-lys-ser-glu; what is the pI? net charge at pH 7.0 and pH...

Given the following sequence asp-cys-met-lys-ser-glu; what is the pI? net charge at pH 7.0 and pH 4.0?

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...

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.

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...

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 tripeptide below: Lys-Glu-Asp Calculate the isoelectric point (pI) of this tripeptide. You can assume...

Examine the tripeptide below: Lys-Glu-Asp Calculate the isoelectric point (pI) of this tripeptide. You can assume that the pKa of the amino terminus is 9.06 and the pKa of the carboxy-terminus is 1.99. a. 2.95 b. 3.99 c. 5.53 d. 6.48 e. 7.31

A peptide has the following sequence: A-K-R-H-G-E-E-R (Ala-Lys-Arg-His-Gly-Glu-Glu-Arg). What is the pI for this peptide? You...

A peptide has the following sequence: A-K-R-H-G-E-E-R (Ala-Lys-Arg-His-Gly-Glu-Glu-Arg). What is the pI for this peptide? You can use even integer approximations for pKa values: I know the answer is 9.5 but I need to know how to get to this answer.

Look at this undecapeptide: Arg Asp Cys Glu Leu Lys Met Phe NH4+. What would each...

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...

Amino acid analysis of a nonapeptide yielded the following: Gly2, Glu, Met2, Lys, Arg2, Thr (subscript...

Amino acid analysis of a nonapeptide yielded the following: Gly2, Glu, Met2, Lys, Arg2, Thr (subscript 2's indicate two glycines, two methionines, and two arginines). Reaction of the intact nonapeptide with Sanger's reagent yielded FDNB-Arg; incubation with trypsin yielded free Arg, free Glu, a tripeptide, and a tetrapeptide. Reaction of the tripeptide with Sanger's reagent yielded FDNB-Gly, and reaction of the tetrapeptide with Sanger's yielded FDNB-Thr. Incubation of the above tripeptide with carboxypeptidase (identifies the C-terminal amino acid) identified Arg....

You have been provided a mixture containing four amino acids (Glu, His, Pro and Lys) to...

You have been provided a mixture containing four amino acids (Glu, His, Pro and Lys) to be separated by ion-exchange chromatography using a Dowex 50 cation-exchange, prepared in a loading buffer at pH 2.0. The following solutions are made available: The amino acid mixture in 0.04M citrate buffer at pH 2.0. 0.04M citrate buffer, pH 4.5 0.04M citrate buffer, pH 8.0 0.04M citrate buffer, pH 10.5 Is complete resolution of all amino acids achieved if the buffers are allowed to...

Draw the tripeptide of Asp-Ser-Lys. Label the N-terminus and C-terminus on your drawing. Also put a...

Draw the tripeptide of Asp-Ser-Lys. Label the N-terminus and C-terminus on your drawing. Also put a box around the atoms of one peptide bond.

Question