INTRODUCTION 



5. Isoleucine, C 6 H 18 NO a , or a-amino-i8-rnethyl-|8-ethyl-propionic acid. 

 CH 3 v 



"CH . CH(NH 2 ) . COOH 



6. Phenylalanine, C 9 H U NO 2 , or |8-phenyl-a-aminopropionic acid. 



C 6 H 5 . CH 2 . CH(NH 2 ) . COOH 



7. Tyrosine, C 9 H n NO 3 , or /8-parahydroxyphenyl-a-aminopropionic acid. 



HO . C 6 H 4 . CH 2 . CH(NH 2 ) . COOH 



8. Serine, C 3 H 7 NO 3 , or |8-hydroxy-a-aminopropionic acid. 



CH 2 (OH) . CH(NH 2 ) . COOH 



9. Cystine, C 6 H 12 N 2 O 4 S 2 , or dicysteine, or di-(-thio-a-aminopropionic acid). 



HOOC . CH(NH 2 ) . CH 2 . S S . CH 2 . CH(NH 2 ) . COOH 



B. Monoaminodicarboxylic acids. 



10. Aspartic acid, C 4 H 7 NO 4 , or aminosuccinic acid. 



HOOC . CH 2 . CH(NH 2 ) . COOH 



11. Glutamic acid, C 6 H 9 NO 4 , or a-aminoglutaric acid. 



HOOC . CH 2 . CH 2 . CH(NH 2 ) . COOH 



C. Diaminomonocarboxylic acids. 



12. Arginine, C C H 14 N 4 O 2 , or a-amino-5-guanidinevalerianic acid. 



/NH 2 



HN=CC 



\NH . CH 2 . CH 2 . CH 2 . CH(NH 2 ) . COOH 



13. Lysine, C 6 H 14 N 2 O 2 , or a, e-diaminocaproic acid. 



H 2 N . CH 2 . CH 2 . CH 2 . CH 2 . CH(NH 2 ) . COOH 



D. Heterocyclic compounds. 



14. Histidine, C 6 H 9 N 3 O 2 , or /8-imidazole-a-aminopropionic acid. 



CH 



/ \H 



CH = C - CH 2 . CH(NH 2 ) . COOH 



15, Proline, C B H 9 NO 2 , or o-pyrrolidine carboxylic acid. 



CH 2 CH 2 



CH a CH . 



COOH 



16. Oxyproline, or oxypyrrolidine carboxylic acid. 



C 6 H 9 N0 3 



17. Tryptophane, C U H 12 N 2 O 2 , or -indole-a-aminopropionic acid 



C CH 2 . CH(NH 2 ) . COOH 



/ \ 

 C 8 H 4 CH 



E. Ammonia. 



