Show how the pI values for the amino acids in Problem 32 (see Table 26-1) are derived. For each amino acid that possesses more than two pK_a values, give the reason for your choice when calculating pI. 

Problem 32(Table 26-1)

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Table 26-1 Natural (25)-Amino Acids (continued) pK, of a-COOH pK, of a-*NH, pk, of acidic Three-letter One-letter Isoelectric R Name code code function in R point, pl Amino containing (continued) CH,CH,CNH, Glutamine Gln Q 2.2 9.1 5.7 (CH),NH, Lysine" Lys K 2.2 9.0 10.5 9.7 NH (CH,),NHČNH, Arginine" Arg R 2.2 9.0 12.5 10.8 H,C Tryptophan" Trp W 2.8 9.4 5.9 H. H.C -NH Histidine" His H 1.8 9.2 6.1 7.6 Mercapto or sulfide containing CH,SH Cysteine" Cys 2.0 10.3 8.2 5.1 CH;CH,SCH, Methionine“ Met M 2.3 9.2 5.7 Carboxy containing CH,COOH Aspartic acid Asp 1.9 9.6 3.7 2.8 CH,CH,COOH Glutamic acid Glu E 2.2 9.7 4.3 3.2 "Essential amino acids. "Entire structure. pK, of conjugate acid. "The stereocenter is R because the CH,SH substituent has higher priority than the COOH group.