Physical Chemistry of Foods

TABLE7.1 Properties of Amino Acid Residues

Name of acid Symbolsa Side chain Reactive group pKb Fc Fd

Glycine Gly G 22 H
Alanine Ala A 22 CH 3 2.1 3.6
Valine Val V 22 CHðCH 3 ÞCH 3 6.3 13.0
Leucine Leu L 22 CH 2 CHðCH 3 ÞCH 3 7.5 16.6
Isoleucine Ile I 22 CHðCH 3 ÞCH 2 CH 3 7.5 16.6
Serine Ser S 22 CH 2 OH Hydroxyl
Threonine Thr T 22 CHOHCH 3 Hydroxyl 1.7 < 0
Aspartic acid Asp D 22 CH 2 CO
2 Carboxyl 4.0
Asparagine Asn N 22 CH 2 CONH 2 Amide
Glutaminc acid Glu E 22 CH 2 CH 2 CO
2 Carboxyl 4.5
Glutamine Gln Q 22 CH 2 CH 2 CONH 2 Amide
Lysine Lys K 22 ðCH 2 Þ 4 NHþ 3 e-Amino 10.6
Arginine Arg R 22 ðCH 2 Þ 3 NHCðNH 2 Þþ 2 Guanidine 12.0
Cysteine Cys C 22 CH 2 SH Thiol 8.5 4.2 1.4
Methionine Met M 22 CH 2 CH 2 SCH 3 Thio-ether 5.4 5.9

Phenylalanine Phe F Phenyl 10.4 8.5

Tyrosine Tyr Y Phenol * 10 9.0 < 0