98 GENERAL BIOCHEMISTRY 



TABLE 5-1. The Amino Acids Commonly Occurring in Proteins 



Amino Acid One Scientific Name (Acids) Structure 



Alanine a-Aminopropionic 



Arginine a-Amino-5-guanidino-n-valeric 



Asparagine Aminosuccinic (amide) 



Aspartic acid Aminosuccinic 



Cysteine a-Amino-/3-thiolpropionic 



Cystine Di(o:-aminopropionic)-/3-disulfide 



Glutamic acid a-Aminoglutaric 



Glutamine a-Aminoglutaric (amide) 



Glycine Aminoacetic 



Histidine a-Amino-/3-imidazolopropionic 



Hydroxyproline 7-Hydroxypyrrolidine-a-carboxyUc 



Isoleucine a-Amino-/3-methyl-7!-valeric 



Leucine a-Aminoisocaproic 



Lysine a,€-Diamino-n-caproic 



Methionine a-Amino-7-methylthiol-n-butyric 



Phenylalanine a-Amino-(3-phenylpropionic 



Proline Pyrrolidine-a-carboxylic 



Serine a-Amino-^-hydroxypropionic 



Threonine a- Amino-/3-hydroxy butyric 



Tryptophan a-Amino-^-indolepropionic 



Tyrosine a-Amino-^-(/)-hydroxyphenyl)-propionic 



Valine a-Aminoisovaleric 



CH3CHNH3+COO- 

 NH2CNHCH2CH2CH2CHCOO- 



!l I 



NH2+ NH2 



NH2OCCH2CHNH3+COO- 



HOOCCH2CHNH3+COO- 



HSCH2CHNH3+COO- 



SCH2CHNH3+COO- 



1 



SCH2CHNH3+COO- 



HOOCCH2CH2CHNH3+COO- 



H2NOCCH2CH2CHNH3+COO- 

 CH2NH3+COO- 



u 



— CH2CHNH3+COO- 



H 

 HOH 



H2' 



o 



H2 



HCOO- 



sN' 

 H2* 

 CH3CH2CHCHNH3+COO- 

 I 



CHs 

 (CH3)2CHCH2CHNH3^COO- 

 H2NCH2CH2CH2CH2CHNH3+COO- 

 CH3SCH2CH2CHNH3+COO- 



o 



H2kN^ 



CH2CHNH3+COO- 



N' 

 H2+ 



H2 

 HCOO- 



HOCH2CHNH3+COO- 

 CH3CHOHCHNH3+COO- 



CO" 



H 



-CH2CHNH3-^COO- 



OCH2CHNH3+COO- 

 (CH3)2CHCHNH3+COO- 



beyond doubt that ordinary amino acids exist in both solid state and 

 simple aqueous solution as dipolar ions or zwitterions. Calculations 

 show that an aqueous solution of glycine, for instance, can have no 

 more than one part of uncharged molecules in a hundred thousand 

 parts of dipolar ions. Hence, it is more accurate to write the structure 

 of glycine as 



CH2GOO- 



NH3+ 



than as 



CH2COOH 



I 

 NHo 



