E. One of the goals you have is to be able to purify this fragment from the rest of the viral peptide sequences to study it further. Propose a specific technique to purify this peptide that takes advantage of chemical or physical properties of this polypeptide fragment. F. With this polypeptide completely purified you seek to use mass spectrometry to determine if any potential post translational modifications exist. To achieve a higher resolution of potential modifications, you cleave the polypeptide using trypsin. Predict the single letter amino acid sequence of the 6 fragments that would be created and what the resulting molecular weight of those fragments would be. G. From your mass spectrometry results you find 6 m/z peaks corresponding to the following molecular weights: 174.2, 245.32, 378.49, 396.45, 407.49, and 601.53 g/mol. Which one fragment from the trypsin digest contains a post translational modification? Why? You determine the post translational modification to be phosphorylation (-PO32). Why does this make sense? Draw the structure of the phosphorylated residue of amino acid that is likely phosphorylated on this fragment. 7 Part III. (16 pts) The proteolytic cleavage of surface proteins of the coronavirus resulted in the following polypeptide sequence. RASCKMTKVKYANRIHGA A. Using the primary sequence of the polypeptide, predict the likely secondary structure that this sequence forms (alpha helix or beta sheet) and explain your rationale. B. Using Table 5.1 in the book calculate the molecular weight of this polypeptide sequence. 2016559701 C. Calculate the pl of this polypeptide sequence. D. Calculate to 2 decimal places the net charge this polypeptide sequence would have at pH 7