Problem 1 Draw the twenty canonical amino acids (encoded in biological proteins) as they would appear at pH = 7, including stereochemistry found in encoded proteins. Next to each amino acid, give its name and both its 3- letter and 1-letter identifications.

Problem #2 a) How many ionizable groups does the tyrosine-alanine-isoleucine-glycine tetrapeptide core of ustiloxin B have? ( b) At neutral pH, what fraction of the total concentration of the tetrapeptide is expected to have the R group of the tyrosine residue in its deprotonated, anionic form (assuming that the pK, of the R group is the same as that of the free amino acid)? c) What is the pl of the tetrapeptide (assuming that the pK,'s of the N- and C-termini are also the same as the corresponding functional groups in a free amino acid)?

Time remaining: 00:08:55 Chemistry Consider a peptide with the following amino acid sequence: H2N-ASENHLDGCPYTKSRG-COOH Analyze the predominate protonation state and thus dominate charge (+1, 0, -1) of the residues in this peptide at pH 3, 6, and 10 by filling in the table below, identifying the relevant pKa appropriate for each residue. (Note that choice of pKa and its. application will be graded independently; e.g., if you can choose the wrong pKa but apply it correctly, you will lose points only for the pKa.) AA Residue pKa Charge pH 3 Charge pH 6 Charge pH 10 A         S         E         N         H         L         D         G         C         P         Y         T         K         S         R         G

Question: What is the thermodynamic driving force behind the formation of a peptide bond and how does it relate to the properties of the amino acid residues involved?