134 THE PROTEINS AND THE AMINO-ACIDS 



if By these various methods the following ammo-acids have been 

 isolated from among the products of hydrolysis of various proteins: 



A. Monoamino-monocarboxylic acids. 

 1. Glycine, or ammo-acetic acid: 



2. Alanine, or a-amino-propionic acid: 



CH 3 .CH(NH 2 ).COOH 



3. Valine, or a-amino-iso-valerianic acid: 



CHs 



CH.CH(NH 2 ).COOH 

 CH 3 



4. Leucine, or a-amino-isocaproic acid: 



CH 3 



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

 CH 3 



5. Isoleucine, or a-amino-/3-methyl-/3-ethylpropionic acid : 



CH 3 \ 



CH.CH(NH 2 ).COOH 

 C 2 H 6 



6. Caprine, or Glycoleucine, or a-amino-normal-caproic acid: 



CH 3 .CH 2 :CH 2 .CH 2 CH(NH 2 ) COOH 



7. Phenylalanine, or 0-phenyl-a-amino-propionic acid : 



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



8. Tyrosine, or jS-parahydroxyphenyl-a-amino-propionic acid: 



HO.C 6 H 4 .CH 2 .ciNH 2 ).COOH 



9. Serine, or jS-hydroxy-a-amino-propionic acid: 



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



10. Cystine, or dicysteine or di- (/3-thio-a-aniino-propionic acid) : 



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



V 



