116 



PROTEINS 



Photo by Horst G. Schneider. 



Fig. 5-10. Trytophan. 

 Classification and formulas of amino acids 



I. MONOAMINO-MONOCARBOXYLIC ACIDS 



A. Aliphatic acids: 



COOH 

 I 

 HoN— C— H 



H 



COOH 

 I 

 H,N-C— H 



CH, 



COOH 

 I 

 HjN— C— H 



I 

 CH2 



CH3 



COOH 

 I 

 H,N-C— H 



CH 



H3C ^CHj 



L-Glycine or L- Alanine or L-Aminobutyric acid L- Valine or 



aminoacetic acid a-aminopropionic a-aminoisovaleric 



acid acid 



COOH 

 I 

 H2N— C— H 

 I 

 CH2 



I 



CH 

 / \ 

 H3C CH3 



COOH 



I 

 H2N— C— H 

 I 



H3C CzHs 



COOH 



I 

 H2N— C— H 



I 

 CH2 



I 

 CH2 



I 

 CH2 



COOH 



I 

 H2N-C— H 



CH2OH 



L- Leucine or L-Isoleucine or 



a-aminoisocaproic /3-methyl-a-amino- 

 acid valeric acid 



CH3 

 L-Norleucine or L-Serine or 



a-aminocaproic a-amino-/3-hydroxy- 

 acid propionic acid 



COOH 

 I 

 H2N— C— H 

 I 



CH2 

 I 

 CH:OH 



L-Homoserine or 



a-amino-7-hydroxy- 



butyric acid 



COOH 



I 

 H2N— C— H 

 I 

 H— C— OH 

 I 



CH3 

 L-Threonine or 

 a-aniino-/3-hydroxy- 

 butyric acid 



