Structures of Amino Acids TABLE19.1 The 20 Common Amino Acids in Proteins pKa pKa pKa side Name Abbreviations MW Stucture a-CO2H a-NH3+ chain pl Neutral Amino Acids 0 Alanine Ala A 89 H3C、 2.34 9.69 6.01 0 H3N H O Asparagine Asn N 132 H2N 2.02 8.80 5.41 O H3N 0 Cysteine Cys C 121 1.96 10.28 8.18 5.07 HS 0 Glutamine Gln Q 146 2.17 9.13 5.65 H2N Glycine Gly G 75 2.34 9.60 5.97 0
Structures of Amino Acids
Structures of Amino Acids Isoleucine 131 2.36 9.60 6.02 0 0 Leucine Leu 131 HgC 2.36 9.60 一 5.98 Methionine Met M 149 2.28 9.21 一 5.74 H3C Phenylalanine Phe 165 1.83 9.13 一 5.48 Proline Pro 115 1.99 10.60 6.30 Cengage Learning.All Rights Reserved
Structures of Amino Acids
Structures of Amino Acids TABLE 19.1 The 20 Common Amino Acids in Proteins continued pKa pKa pKa side Name Abbreviations MW Stucture a-CO2H a-NH3+ chain Neutral Amino Acids continued Serine Ser 105 2.21 9.15 5.68 HO H HO H Threonine Thr 119 2.09 9.10 5.60 H3C H3 Tryptophan Trp 2 204 2.83 9.39 5.89 Tyrosine Tyr 181 2.20 9.11 10.07 5.66 HO CH3 Valine Val 117 2.32 9.62 5.96 H3C 0
Structures of Amino Acids
Structures of Amino Acids Acidic Amino Acids Aspartic Asp 0 133 0 1.88 9.60 3.65 2.77 acid O H3N Glutamic Glu E 147 2.19 9.67 4.25 3.22 acid H3N Basic Amino Acids +NH2 Arginine Arg R 174 2.17 9.04 12.48 10.76 H>N Histidine His H 155 1.82 9.17 6.00 7.59 H3 Lysine Lys 146 H3 2.18 8.95 10.53 9.74 Cengage Learning.All Rights Reserved
Structures of Amino Acids
Structures of Amino Acids All 20 amino acids found in proteins are a-amino acids The amino group in each is a substituent on the a carbon atom-the one next to the carbonyl group 19 of the amino acids are primary amines,RNH2 Differ in the side chain,the substituent attached to the a carbon Proline,a secondary amine,is the only amino acid whose nitrogen and a carbon atoms are part of the ring Side chain H3N H HH A primary a-amino acid Proline,a secondary a-amino acid
All 20 amino acids found in proteins are a-amino acids ▪ The amino group in each is a substituent on the a carbon atom – the one next to the carbonyl group ▪ 19 of the amino acids are primary amines, RNH2 ▪ Differ in the side chain, the substituent attached to the a carbon ▪ Proline, a secondary amine, is the only amino acid whose nitrogen and a carbon atoms are part of the ring Structures of Amino Acids