Protein Complexes as Biochemically Active Systems 471 



that the functions of both the protein and the non-protein components of the 

 complex will depend on the type of bond, on the chemical groups affected by 

 them and their influence on protein macrostructure. What appears particularly 

 important is the alteration of the catalytic functions of the proteins in the pro- 

 cess of complex formation, which, judging from all the available information, 

 may play a certain controlling role in the creation of the multitude of enzymic 

 processes which take place in a living organism. The discovery of such alterations 

 would provide a basis for a deeper understanding of the mechanism of enzymic 

 activity of the Hving cell and would help to establish certain notions concerning 

 the possible paths of evolution of the primary proteins. 



Owing to the importance of nucleic acids and Hpids in the organism, investi- 

 gators naturally gave their attention first to studying the influence of these types 

 of compounds on the activity of certain proteolytic and hydrolytic enzymes. 

 Slavik & Smetana [8] demonstrated that yeast ribonucleic acid (RNA) and 

 adenine in physiological concentrations inhibit the action of proteinases below 

 their isoelectric point. Chepinoga & Pavlovskii [9] established the reversible 

 inhibition of the enzymic activity of aldolase and enolase on their combining 

 with nucleic acids, especially with highly polymerized deoxyribonucleic acid. 

 It was discovered by Sorm & Grubesova [10] that pancreatic proteases are 

 inactivated by pancreatic RNA. It is noteworthy that the inhibition of the protease 

 activity of chymotrj^sin does not involve alteration of its ability to participate 

 in polypeptide synthesis. Robert & Polonovsky [11] fovmd that the destruction 

 of lipoprotein complexes enhances the activity of milk xanthine oxidase, while 

 Spiegelman [12] revealed that treatment of the protoplasts of Bacillus megaterium 

 by trypsin and lipase totally suppresses the synthesis of enzymes in these proto- 

 plasts. There are a number of indications that protein substrates, when asso- 

 ciated with nucleic acids, lipids or polysaccharides, are more stable to attack by 

 a number of enzymes [13]. The study of the action of pharmacologic agents in 

 the organism revealed that interaction with proteins reduces the physiological 

 activity of a niraiber of drugs. Thus, blood plasma lowers the activity of peni- 

 cillin [14]; interaction with serum albumin reduces the antibacterial activity of 

 oleic acid with regard to Mycobacterium tuberculosis [15] and the haemolytic 

 activity of the fatty acids with respect to erythrocytes [16], and so on. TheUmited 

 data at our disposal at present thus definitely confirm the view that when pro- 

 teins form complexes with other substances, this can appreciably alter the 

 activity of both components. 



Another trend in the study of Hpoproteins aims at elucidating their rôle in 

 the formation of coacervates, the surface layers of cellular organoids, proto- 

 plasmic membranes and other structural elements of living matter. Bungenberg 

 de Yong [17] demonstrated, in a series of papers, that the first stage in protein 

 and hpid coacervation is the formation of complexes between them, with surface 

 phenomena at the interphase playing a substantial part. There is an extensive 

 literature [18-20] to confirm that protein and Hpoprotein surface layers play 

 an important part in the formation of cellular structures, determining not only 

 the permeability of these structures, but also, largely, the metabolic processes 

 in the protoplasm. It is natural to assume therefore, that great importance in 



