78 CONJUGATED PROTEINS 



It is, however, becoming clear that organization, as observed 

 on the macroscopic and microscopic levels, must be matched, on 

 the submicroscopic and molecular levels, by the existence of pat- 

 terns in which the varied arrangement of a limited number of 

 constituents serves to impress individuality and specificity on cells 

 or cell communities. One could venture the opinion that biochem- 

 ical evolution is accompanied, or indeed caused, by the for- 

 mation of macromolecules of ever-increasing complexity com- 

 posed of an ever-diminishing number of constituents. One 

 mechanism by which this may be accomplished is that of conjuga- 

 tion. Many different conjugated proteins are being recognized, 

 such as the nucleoproteins, the lipoproteins, the mucoproteins, 

 or the chromoproteins; many enzymes that carry cof actors, dis- 

 tributed in specific positions on the protein molecule, belong to 

 one or the other of these groups. But we encounter also lipopep- 

 tides, mucolipids, etc.; and many more unrecognized compounds 

 of this type must daily be going down the drains of our labora- 

 tories than repose in the graveyards of our scientific journals. 

 When I am sometimes told that biochemistry has "run out of 

 good problems", I shudder and reply: "Biochemistry has not 

 even begun!" 



The general aspects of the problem of conjugation have rarely 

 been formulated clearly. This is perhaps not surprising, for this 

 class of substances has long found itself between two chairs, as it 

 were: too big to be handled conveniently by the chemist; too 

 small to be seen consistently by the morphologist. The chemist 

 strove for the isolation of the smallest unit endowed with homo- 

 geneity; the biologist attempted the recognition of the simplest 

 structure endowed with function. The prize went to the loudest 

 prophet with monomaniac intent. Since scientists in our time 

 have, on the whole, lost the ability to say "We don't know", it is 

 usually the man with the premature explanations that brings 

 home the bacon; and by the time he has been found out he will 

 have devoured it. 



Another obstacle to the recognition of the biological impor- 

 tance of the conjugated proteins may be seen in their being 



