Consider a peptide with the sequence Ala-Glu-Arg-Leu. Assume the ionizable groups have the pKa values listed in Table 2.1 of your text. (a) Draw the predominant ionic form of the peptide at pH 7.4. (b) Determine the net charge of the predominant form of the peptide at pH 7.4. (c) Calculate the pI of the peptide.

At which pH would the peptide with the amino acid sequence 'KEYHR' be found in an IPG (Immobilized pH gradient) strip after successful isoelectric focusing. Show calculation. lonizable groups Alpha amine group of K Side chain group of K Side chain group of E Side chain group of Y Side chain group of H Side chain group of R Alpha carboxylic acid group of R pka 8.95 10.53 4.25 10.07 6 12.48 2.17

What is the net charge on the peptide RHTLE at pH 12.5?

The amino acid arginine ionizes according to the following scheme: (a) Calculate the isoelectric point of arginine. You can neglect contributions from form I. Why? (b) Calculate the average charge on arginine when pH = 9.20. (c) Is the value of average charge you calculated in part b reasonable, given the pI you calculated in part a? Explain your answer

Consider the peptide Trp-Arg-Glu-Cys-Gly-Tyr. For the drawings requested below,  please show them in zig-zag style, from amino to carboxy terminus, with correct  stereochemistry Draw the predominant form at pH = 2  Draw the predominant form at pH = 5  Draw the predominant form at pH = 7  Draw the predominant form at pH = 12

Please draw titration curves for peptide HFDTYA and HEKDGQ, and calculate the pl for each. Usethis information to explain why the peptide HFDTYA has low solubility and HEKDGQ has a highersolubility in bulk water at pH = 7.

Consider a short peptide with the sequence M-C-Q-L-Y-P-E-D-K. List the ionizable groups in this peptide, and the net charge of the whole peptide at pH a) 1.5, b) 7.0, and c)12.0.

There is parts A-D for the picture provided. A) A peptide has the sequence, Arg-Cys-His-Tyr-Glu-Asn-Lys-Asp. What is the net charge at pH 1? Choices: -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5   B) A peptide has the sequence Arg-Cys-His-Tyr-Glu-Asn-Lys-Asp. What is the net charge at pH 5?   Choices: -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5   C) Same Peptide sequence, What is the net charge at pH8.5, (N-terminus is pronated) Choices:    -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5   D) A  peptide has the sequence, Arg-Cys-His-Tyr-Glu-Asn-Lys-Asp. What is the net charge at pH 13?   Choices: -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5   Thank You!

1) Indicate the total charge of the peptide at pH 7.0, 9.0, and 11.0 2) Determine the isoelectric point (pI) for this peptide. Show the relevant pKa’s and your calculation.  3) What is the fraction of the peptide that has the N-terminal amino group deprotonated at pH 9.

calculate the net charge of your peptide at I) pH 2.0; ii) pH 6.0 iii) pH 7.0; iv) pH 11.5. show full working and include justification as to how you determined the charge of WEIJIN peptide