Determine the net charge on the following pentapeptide "Lys-Ala-His-Asp-Ser" at: a. pH 1.0 b. pH 10.1

you have isolated the following peptide: His-Ser-Arg- Ala-Glu- Leu- Pro- Gly Calculate the approximate charge of the peptide at Ph 1, 3, 5, 8, 11, 14 AND what is the PI of this peptide?

Draw the Ala-Ser-Leu-Asp polypeptide (perspective formula) showing the fully extended backbone geometry (all angles +/- 180°). Include correct stereochemistry for L-amino acids. Label all bond rotations representing the angles at each residue

Hemoglobin is considered to be a tetrameric complex with a 64 kDa (α β)2. When attempting to purify hemoglobin, we must first purify the α and β monomers (about 16 kDa each) to prepare the tetramer. This is formed from the dimer intermediate: 2 α + 2 β -> 2 αβ -> (α β)2. 1. The graph given represents a size-exclusion chromatogram after the refolding of the hemoglobin tetramer. This process is not 100% efficient, so we may have leftovers of dimers and monomers. In the graph given, can we label the peaks given as a tetramer, dimer, or monomer?

the following peptide is incubated as chymotrypsin: Gly-Val-Phe-Lys-Ala. Present the detailed chemical mechanism by which chymotrypsin hydrolyzes this peptide. Briefly explain each step. Include only the structure of the final products of the reaction.

Draw the structure of Pro-Leu-Glu at physiological pH (7.4).

Draw two different possible hydrogen-bonding interactions between two molecules of formamide (HCONH2). Clearly label the hydrogen-bond donor and acceptor atoms. Which of these two possible hydrogen-bonding interactions is more likely to occur? (Hint: Consider resonance structures for formamide.)

Identify the primary structure of a hexapeptide containing five different amino acids if the following smaller peptides are among the partial hydrolysis products: Gly-Cys, Ala-Ser, Ala-Gly, and Cys-Val-Ala

Draw the structure of the PTH derivative you would obtain by Edman degredation of the peptide: ALPF.

Discuss the reaction conditions you would need to carry out the PEGylation reaction of this peptide and explain how the pH affects the selectivity of these reactions.