Biosynthesis of Enzymes and their Origin 459 



for this primitive living thing in the appropriate concentrations. It is only later 

 evolution, which led to the formation of the specific enzymes, necessary for 

 organisms which can live on simpler materials, transforming simpler compounds 

 to the necessary ones. 



It appears at first sight a weak point to suppose the induction of enzymes, 

 able to supply materials that are missing from the environment, i.e. induction 

 through the absence of a substrate. This is however not so fantastic if we think 

 of the reversibihty of enzyme reactions : the presence of the necessary organic 

 compounds at the beginning elicits the inductive formation of enzymes which 

 decompose them into smaller compounds. When the original compounds were 

 not present any more, only their decomposition products, the reverse function 

 of the enzyme was able to sustain life under the changed conditions. 



If we suppose that an organism produces a limited number of precursor pro- 

 teins or precursor polypeptide chains, and each of these may give rise upon 

 induction to several enzymes, and if we suppose that the presence of a variety 

 of enzymes to catalyse metabolic reactions was not a prerequisite of the primi- 

 tive Uving system, we can visualize metabolism, which is the basic definitive 

 property of the living of to-day, as being acquired later in the course of develop- 

 ment than reduplication of living matter. 



REFERENCES 



1. À. Ullman & F. B. SxRAxra, Acta physiol. hung., 6, 377, 1954. 



2. Ä. Ullman & F. B. Straub, Acta physiol. hung., 8, 278, 1955. 



3. À. Ullman & F. B. Straub, Acta physiol. hung., 10, 137, 1956. 



4. Â. Ullman & F. B. Straub, Acta physiol. hung., 11, 11, 1957. 



5. Â. Ullman & F. B. Straub, Acta physiol. hung., 11, 31, 1957. 



6. T. Garzô, K. Perl, M. T.-Szabô, à. Ullman & F. B. Straub, Acta physiol. hung.i 



II, 23, 1957. 



7. T. Peters, J. biol. Chem., 200, 461, 1953. 



8. H. Green & H. S. Anker, J'. gen. Physiol., 38, 283, 1955. 



9. L. C. U. Junqueira, C. G. Hirsch & H. A. Rothschild, Biochem. J., 61, 275, 1955. 



10. M. Kramer & F. B. Straub, Acta physiol. hung., 11, 133, 1957. 



11. M. Kramer & F. B. Straub, Acta physiol. hung., 11, 139, 1957. 



12. M. Kramer & F. B. Straub, Biochim. biophys. Acta, 21, 401, 1956. 



