76 PHYSIOLOGICAL CHEMISTRY 



Osborne, however, much light has been thrown on the subject. 

 It has been found that proteins if boiled with concentrated acids, 

 with alkalies, or if acted on by certain enzymes will break down 

 ultimately into fairly simple chemical substances. These are 

 the oc amino acids. On hydrolysis, all proteins are broken 

 down into a mixture of these compounds, of which about 

 twenty have been obtained from proteins. All proteins, what- 

 ever their nature, yield these same compounds. All the ammo 

 acids are not obtained from every protein, but in general a pro- 

 tein yields most of them. Many proteins lack one, two, three, 

 or perhaps more, and a few proteins are made up of relatively 

 few different amino acids. The analytical methods in use do 

 not give products to the amount of 100% of the original pro- 

 tein, for there are losses at various stages in the process. Usu- 

 ally only about % of the original substance is accounted for. 

 From some proteins 85-90% has been recovered, and in the 

 case of salmine 110%, this apparently impossible result being 

 accounted for by the taking up of water when the amino acid 

 complexes are split up. It is easy to understand the causes for 

 the difference in behavior of different proteins. Although they 

 all are made up of practically the same amino acids, these are 

 present in different proteins in widely varying proportions, 

 and also undoubtedly are arranged or put together differently. 

 The following is a list of the amino acids which thus far have 

 been obtained by the hydrolysis of proteins. It is quite pos- 

 sible that as time goes on others will be added. 



Amino Acids Obtained by Hydrolyzing Protein 



A. Monoamino monocarboxylic acids. 



1. Glycocoll NH 2 CH 2 COOH 



2. Alanine CH 3 CHNH 2 COOH 



3. oc Amino Butyric CH,CH CHNH 2 COOH 



CH \" 



4. Valine CH CHNH 2 COOH 



CH 3 



