The Aliphatic Branched-Chain Amino Acids

Valine is unique among the nutritionally essential amino acids in that its deficiency in the rat causes, in addition to loss of appetite and stunted growth, a syndrome in which the animal becomes extremely sensitive to touch and displays a severe incoordination of movement.  

Propionic acid Acrylic acid L-Lactic acid 

As with most other amino acids, the catabolism of valine is initiated by removal of its amino group, in this case to yield a-ketoisovaleric acid. L-Valine is readily susceptible to transamination, and it is slowly attacked by L-amino acid oxidase. The n-valine is readily deaminated by D-amino acid oxidase.  

Valine is glycogenic and antiketogenic. From the observation that a-ketoisovaleric acid and isobutyric acid, as well as valine, each con- 

The oxidation of propionic acid has been studied extensively because the dissimilation of odd-numbered carbon acids leads to the production of this acid. Another reason for the interest in this acid is that the catabolism of propionate is an apparent example of the a-oxidation of a fatty acid, which certainly appears to be not found in connection with the catabolism of either the straight-chain or branched-chain carbon acids. 

As with most other amino acids, the catabolism of valine is initiated by removal of its amino group, in this case to yield a-ketoisovaleric add. 

Valine is glycogenic and antiketogenic (78, 79). From the observation that a-ketoisovaleric acid and isobutyric acid, as well as valine, each contributed three of their carbons to the formation of glucose. Rose and coworkers (80) postulated the steps 1 and 2 shown in Fig. 5 in the catabolism of valine. Subsequently Atchley (81) was able to show that isobutyric acid is converted to propionic acid by the action of the fatty acid-oxidizing systems of liver and kidney. 

Kinnory and associates (89) demonstrated the formation of radioactive a-ketoisovaleric, isobutyric, /3-hydroxyisobutyric, and propionic acids from 

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