ORIGIN OF ENZYMES 371 



This sort of structure of carboxylase is a demonstrable 

 instance of one case of the internal organisation of proto- 

 plasm. So long as only the separate parts of the enzyme are 

 present or these parts are not combined with one another in 

 a special way, their catalytic activity is small and they carry 

 out their function in the living body badly. If the enzyme 

 is to have its characteristic efficiency in this respect its separ- 

 ate components must be combined together in a special way, 

 but this cannot occur by chance. 



Catalase may serve as another analogous example. As we 

 have already pointed out, even ferric ions can catalyse the 

 breakdown of hydrogen peroxide to water and oxygen, but 

 this is only a weak effect. If the iron is combined with a 

 porphyrin nucleus to form haemin, the catalytic activity is 

 increased about a thousand fold. In the natural enzyme, 

 catalase, the haemin is combined with a specific protein and 

 this further increases its catalytic activity many million fold. 



In the systems which we postulated as being the starting 

 point for the process of evolution on the Avay to the origin 

 of life, in coacervate drops having the properties of open 

 systems, the chemical reactions which formed the network 

 of the system must, at first, have occurred very slowly. A 

 certain speeding up of isolated reactions may have been 

 achieved, mainly by means of the catalytic effect of such 

 inorganic salts (e.g. those of calcium, iron, copper and vana- 

 dium) as may have been present in large enough quantities 

 in the waters of the primaeval ocean. 



Certainly even such a very slight increase in rate must 

 have played a decisive part in the establishment of a definite 

 sequence of reactions, in the organisation of the network of 

 chemical processes in our open systems. 



In particular, owing to the catalytic activity of inorganic 

 iron, the breakdown of hydrogen peroxide into water and 

 oxygen might thus have occupied a place in the network if 

 it somehow favoured the dynamic stability of the drop, its 

 preservation for a long time or even its gro^vth under the 

 conditions of its interaction with the external medium. 



NoAV, let us suppose that some of these coacervate drops, 

 owing to their adsorptive powers or for other reasons, could 



