THE PROTEINS AND THEIR METABOLISM 85 



3. a-amino butyric acid. 

 CH 3 



CH 



COOH 



4. Valin or a-amino iso-valerianic acid or a-amino (3-methyl butyric 

 acid. 



CH 3 CH 3 



\ / 

 P-CH 



COOH 



5. Leucin. or a-amino y-methyl valerianic acid. 



CH 3 CH 3 



\/ 



Y-CH 



a-CHNH 2 



I 

 COOH 



6. Iso-leucin or a-amino |3-methyl valerianic acid. 

 CH 3 



Y-CH 2 

 CH 3 -P-CH 



COOH 



