4 THE AMINO ACIDS 



three large groups, namely, the Simple Proteins, the 

 Conjugated Proteins and the Derived Proteins. 

 Simple Proteins may be defined as substances which 

 yield only a-amino acids or their derivatives on hydrol- 

 ysis. Conjugated Proteins are substances which con- 

 tain the protein molecule united to some other mole- 

 cule or molecules otherwise than as a salt. As their 

 name implies, the Derived Proteins are substances that 

 have been formed from naturally occurring proteins. 

 The various sub-divisions of these large groups, as 

 adopted by the American Physiological Society and 

 the American Society of Biological Chemists, follow: 



Simple Proteins Conjugated Proteins 



1. Albumins. 1. Nucleoproteins. 



2. Globulins. 2. Glucoproteins. 



3. Glutelins. 3. Phosphoproteins. 



4. Alcohol-Soluble Proteins. 4. Hemoglobins. 



5. Albuminoids. 5. Lecithoproteins. 



6. Histones. 



7. Protamines. 



Derived Proteins 



A. Primary B. Secondary 



Protein Derivatives. Protein Derivatives. 



1. Proteans. 1. Proteoses. 



2. Metaproteins. 2. Peptones. 



3. Coagulated Proteins. 3. Peptides. 



