APPENDIX 253 



Glutelins. Simple proteins, heat coagulable, insoluble in water or 

 dilute salt solutions, but soluble in very dilute acids or alkalies. 



Prolamins. Simple proteins, insoluble in water but soluble in 

 80% alcohol. 



Albuminoids. Simple proteins, insoluble in dilute acid, alkali, 

 water or salt solution. 



Histons. Simple proteins, not coagulable by heat, soluble in 

 water and dilute acids; strongly basic. 



Protamins. Simple proteins, basic, noncoagulable by heat, sol- 

 uble in ammonia. 



As far as the use of these substances in nonspecific therapy is con- 

 cerned interest has centered so far almost wholly on the native pro- 

 teins of the serum, including serum albumin and globulin as well as 

 fibrinogen. If the proteins used for injection include plant pro- 

 teins, other members of this group will, of course, be involved. No 

 study has been made dealing with the relative advantage or dis- 

 advantage of various native proteins for therapeutic injections. 



The Conjugated (or Compound) Proteins. These are compounds 

 of some simple protein with some nonprotein group, the latter usually 

 acid in nature. They are subdivided as follows: 



Chromoproteins (Hemoglobins). These are proteins in which 

 the nonprotein addition group is colored, as hematin in hemoglobin. 



Glycoproteins (Glucoproteins) . The prosthetic group in this class 

 contains a carbohydrate radical. Mucin and cartilage are examples. 



Phosphoproteins. Proteins derived from the cytoplasm. The ad- 

 dition group contains phosphoric acid. Casein belongs to this group. 



Nucleoproteins. Proteins of the nucleus, i.e., chromatin. Nucleic 

 acid is here the added radical. Nuclein, nucleohiston, etc., are ex- 

 amples. 



Lecithoproteins. These have not been isolated in pure form. To- 

 gether with the Lipoproteins their existence is probable, the former 

 consisting of proteins to which lecithins or phospholipins have been 

 attached, the latter of proteins in combination with one or more of 

 the higher fatty acids. It is possible that the forms are easily dis- 

 sociated and vary from loose and transient physical aggregates to 

 relatively more stable chemical combinations. Their very lability 

 would make them of great physiological importance in cellular 

 processes. 



The conjugated proteins are of considerable importance from the 

 point of view of nonspecific reactions. On injection they are followed 

 in general by relatively little reaction, but the organism can become 

 sensitized to these proteins just as to simple proteins of the first 

 group. When the conjugated proteins are dissociated from their non- 

 protein radicals they produce a far greater reaction than when in 

 the conjugated form. Schittenhelm and his associates have demon- 

 strated this with the chromoproteins. 



