INTRODUCTION 



4. Leucine, C 6 H 13 NO 2 , or a-aminoisocaproic acid. 



CH 3 \ 



)CH . CH 2 . CH(NH 9 ) . COOH 

 CH 3 / 



5. Isoleucine, C 6 H 13 NO 2 , or a-amino-|8 rnethyl-0-ethyl-propionic acid. 



CH 3 \ 



3 \CH . CH(NH 2 ) . COOH 



6. Phenylalanine, C^^NGa, or 0-phenyl-a-aminopropionic acid. 



C 6 H 3 .CH 2 .CH(NH,).COOH 



7. Tyrosine, C 9 H n NO 3 , or j8-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 



g. Cystine, C 6 H 12 N 2 O 4 S 2 , or dicysteihe, 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~NO 4 , or aminosuccinic acid. 



HOOC . CH 3 . CH(NH 9 ) . COOH 



11. Glutamic acid, C 5 H 9 NO 4 , or o-aminoglutaric acid. 



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



C. Diaminomonocarboxylic acids. 



12. Arginine, C 6 H ]4 N 4 O 2 , or a-amino-5-guanidinevalerianic acid. 



/NH, 

 HN=C/ 



\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 /3-imidazole-a-aminopropionic acid. 



CH 



/ \ 

 N NH 



I I 



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



15. Proline, C 5 H 9 NO 2 , or a-pyrrolidine carboxylic acid. 



CH 2 CH 2 



CH 2 CH. 



COOH 



\/ 

 NH 



16. Oxyproline, C B H 9 NO 3 , or ^-hydroxy-o-pyrrolidine carboxylic acid. 

 HO . CH CH 2 



CH 2 CH.COOH 



\/ 

 NH 



