THE PROTEINS AND THEIR STRUCTURE 75 



as composed of polymerized molecules, formed in the main of 

 ammo-acid molecules linked together by their otherwise un- 

 satisfied NH and CO affinities. Thus, to modify Hofmeister's 

 illustration, we may represent a portion, at least, of the peptone 

 molecule as follows : 



Each section between the dotted lines represents an amino- 

 acid nucleus. I speak of these as glycocoll, leucin, etc., but 

 it will be seen that in the leucin nucleus, for example, an H 

 of the NH 2 group is replaced by the CO of the glycocoll nucleus, 

 and the hydroxyl of the COOH group by the NH of the ty rosin 

 nucleus. In Fischer's terminology the nucleus is leucyl, not 

 leucin. The peptone molecule is thus represented as composed 

 of a main chain in serial repetition of glycocoll molecules, 



(H) NH-CH-CO (OH), 

 (H), 



in which the NH affinity on the one side and the CO on the 

 other have been satisfied by linkage with a like molecule, while 

 an H of the CH 2 is substituted (in the figure) by methyl-para- 

 oxybenzene, acetic acid, butylamin, etc. We have, that is to 

 say, a main glycocoll chain with a series of free-swinging chains 

 capable of being replaced or modified by processes of oxidation 

 or the action of enzymes. 1 



1 So as not to introduce complications I have here purposely left out of 

 account a consideration of the relationship of the purin nuclei or radicles to 

 such chains ; it is necessary, however, to keep in mind that the latter are 

 important constituents of the nuclear matter, and of what later I shall refer to 

 as the biophores. 



