Protein Complexes as Biochemically Active Systems 



187 



Inhibition of proteolysis in the presence of DNA was also observed when 

 heat-denatured egg albumin or casein were used as substrates of tryptic 

 hydrolysis. 



The experimental results here reported show that enzymic processes in vitro 

 can be affected by the presence in the reaction mixture of small quantities of 

 substances such as hpids or nucleic acids, which are capable of interacting with 

 the proteins taking part in the process. In the highly complex and mialticomponent 

 system of the Uving cell such effects are evidentiy much more pronounced, and 

 they are made still more complicated by the influence of the numerous interfaces 

 between cellular organoids. 



^ 40 



Fig. 7. The kinetic curves for the proteolysis of serum albumin by trypsin at 

 various DNA/substrate ratios (see text). 



The author is of the opinion that the formation of complexes by primordial 

 proteins with one another and with other organic substances could have given 

 rise to an enormous variety of compounds and chemical processes which, in 

 the course of subsequent evolution, could have produced various conjugated 

 proteins possessing specific biochemical fimctions, and could have engendered 

 the whole set of enzymic processes essential to Hfe. 



The author wishes to acknowledge the participation of V. Z. Baranova, M. I. Bystrova 

 and G. F. Ivashchenko in the experimental work. 



REFERENCES 



1. A. I. Oparin, The Origin of Life on Earth. 3rd. ed. Izd. Akad. Nauk S.S.S.R., 



Moscow, 1957. 



2. D. F. Waugh, Advanc. Protein Chem., 9, 326, 1954. 



3. O. P. Chepinoga, Nucleic Acids and Their Biological Significance. Izd. Akad. Nauk 



Ukr.S.S.R., Kiev, 1956. 



4. E. Chargaff, M. Ziff & D. H. Moore, J. biol. Chem., 139, 383, 1941. 



