THE NITROGEN COMPOUNDS 61 



DEBIVED PROTEINS 



These are divided into primary and secondary protein 

 derivatives. Primary protein derivatives are those that 

 have been slightly modified by the action of water, very 

 dilute acids, or enzyms, or are the result of the action of 

 acids and alkalies whereby products soluble in weak 

 acids and alkalies are formed. Coagulated proteins 

 resulting from the action of heat and alcohol are classed 

 in this division. 



Secondary protein derivatives are those in which the 

 modifying changes (hydrolytic, or the taking up of water) , 

 through the action of acids or enzyms, have proceeded 

 beyond the incipient stage with the formation of bodies 

 that are soluble in water. In this division, the most 

 important compounds are the prpteoses and the peptones, 

 the latter having suffered a greater change by hydrolysis 

 than the former. 



1. PRIMARY PROTEIN DERIVATIVES 



79. Proteans and metaproteins. — ^When proteins are 

 acted on by acids or alkalies, they are modified in 

 proportion to the strength of the reacting acid or alkali 

 and the length of time that the action continues. With 

 acid or alkalies of suflacient strength, there are formed 

 products soluble in weak acids and alkalies (meta-pro- 

 teins). 



80. Coagulated proteins. — ^There are several agents 

 which convert albumins and other proteins into a coagu- 

 lated mass, such as a boiling heat, alcohol, and certain 

 neutral salts and the action of an enzym. For instance, 



