114 PHYSIOLOGICAL CHEMISTRY 



Crustacea. Hemocyanin generally contains either copper, manganese, 

 or zinc in place of the iron of the hemoglobin molecule. For the prepa- 

 ration of hemoglobin in crystalline form see Chapter XV. 



The lecitho proteins consist of a protein molecule joined to lecithin. 

 They have been comparatively little studied and may possibly be 

 mixtures of protein and lecithin. 



For consideration of nucleo proteins see Chapter VI. 



DERIVED PROTEINS 



These substances are derivatives which are formed through hydro- 

 lytic changes of the original protein molecule. They may be divided 

 into two groups, the primary protein derivatives and the secondary 

 protein derivatives. The term secondary derivatives is made use of 

 in this connection since the formation of the primary derivatives gener- 

 ally precedes the formation of these secondary derivatives. These 

 derived proteins are obtained from native simple proteins by hy- 

 drolyses of various kinds, e.g., through the action of acids, alkalis, 

 heat, or enzymes. The particular class of derived protein desired 

 regulates the method of treatment to which the native protein is 

 subjected. 



Primary Protein Derivatives 



The primary protein derivatives are " apparently formed through 

 hydrolytic changes which involve only slight alterations of the protein 

 molecule." This class includes proteans, metaproteins and coagulated 

 proteins. 



PROTEANS 



Proteans are those insoluble protein substances which are produced 

 from proteins originally soluble through the incipient action of water, 

 enzymes, or very dilute acids. It is well known that globulins become 

 insoluble upon repeated reprecipitation and it may possibly be found that 

 the greater number of the proteans are transformed globulins. Osborne, 

 however, believes that nearly all proteins may give rise to proteans. 

 This investigator who has so very thoroughly investigated many of 

 the vegetable proteins claims that the hydrogen ion is the active agent 

 in the transformation. The protein produced from the transformation 

 of edestin is called edestan, that produced from myosin is called myosan, 

 etc. The name protean was first given to this class of proteins by Os- 

 borne in 1900 in connection with his studies of edestin. 



