THE END-PRODUCTS OF PROTEIN HYDROLYSIS 135 



B. Monoaminodicarboxylic acids. 

 11. Aspartic acid, or amino-succinic acid: 



HOOC.CH 2 CH(NH 2 ) .COOH 



. 12. Glutamic acid, or a-aminoglutaric acid: 



HOOC.CaHjCHaCHCNHiO.COOH 



C. Diaminomonocarboxylic acids. 



13. Arginine, or a-amino-3-guanidine-valerianic acid: 



x NH 2 



HN = C 



NH, .CH 2 CH 2 .CH(NH 2 ) .COOH 



14. Lysine, or a-oj-diaminocaproic-acid : 



C WvH 2 N.CH 2 .CH 2 .CH 2 .CH(NH 2 ) .COOH 



D. Heterocyclic amino-acids. 



.15. Histidine, or /3-immazolyl-a-amino-propionic acid: 



N NH 



CH= =C.CH 2 .CHCNH 2 ).COOH 



* 16. Proline, or pyrrolidine carboxylic acid: 



CH 2 - - CH 2 



CH 2 CH.COOH 



17. Oxyproline, or hydroxy-a-pyrrolidine-carboxylic acid 

 Either:' 



HOCH CH 2 



CH 2 CH.COOH 



or: 



CH 2 - CHOH 



CH 2 CH.COOH 



18. Tryptophane or /3-indole-o:-aminopropionic acid 



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



/\ 



C 6 H 4 CH 



/ \/ 



NH 



