COFACTORS OF EnZYMIC ADAPTATION 213 



derived from threose by T. The treatment consists in heating 

 an acidified aqueous solution of the pure sugar, and the 

 chemical structure of these derivatives is actually being 

 investigated by Dr. Asselineau and Prof. Lederer. Further- 

 more, certain batches of commercial preparations of tetroses 

 are contaminated by substances that have biological pro- 

 perties analogous to those obtained by synthesis from pure 

 C4 sugars. 



To verify the hypothesis that tetrose derivatives are in- 

 volved in the two functions of the genetic material, the 

 autocatalytic and the heterocatalytic one, we have studied 

 their action in four biological systems listed in Table I. Every 

 system has its own particular advantages and drawbacks, and 

 can provide adequate answers only to a certain type of ques- 

 tion. A general conclusion can be drawn if a reasonably 

 coherent picture is obtained by comparing results of the en- 

 semble. The principal information we can gain from the first 

 system is whether the cofactors may be involved in the trans- 

 mission, from the mother cell to the daughter cell, of the 

 genetic material responsible for cytochrome oxidase synthesis ; 

 to be more precise, whether they interfere with the interrup- 

 tion, brought about by euflavine, of the normal transmission 

 process. Analogous information can be obtained from the 

 study of the fourth system, with the advantage that the 

 mutation occurs spontaneously. This last system has a con- 

 siderable drawback, however, because of a possible effect on 

 the selection of mutants which precludes any rigorous inter- 

 pretation as to the mutation process. The study of mutation 

 by these two methods is relevant to autocatalysis but gives us 

 no information in respect to heterocatalysis. Data on this 

 point are given by the study of the second and third systems, 

 where enzyme synthesis takes place against a constant 

 genetic background. Furthermore, comparison of the first 

 with the second system enables us to study the two functions 

 of the same genetic material, while comparison of the second 

 with the third permits us to follow the heterocatalytic func- 

 tions of two different genetic materials. 



