CATALYSIS: THE GUIDE OF LIFE 107 



lysts may become sources of "quanta" of kinetic energy. Despite 

 the influence of surrounding aqueous material, they may thus 

 increase the intraparticulate activity or resonance of some mole- 

 cules, or give them momentarily an increase in kinetic motion, 

 corresponding in effect to what a relatively high temperature 

 might do. A molecule so activated and accelerated could become 

 highly reactive. In some cases, activation might be imparted to a 

 specific portion of a large molecule or complex. These physico- 

 chemical aspects of the chemical changes which take place enable 

 us to form some reasonable picture as to how the "driving" energy 

 is distributed and utilized in what biological chemists term 

 "coupled reactions." 



In considering the significance of coupled reactions for the enzymic 

 hydrolysis and synthesis of proteins, Drs. Max Bergmann and Joseph 

 S. Fruton 19 point out that thermodynamic data alone tell us only the 

 approximate amount of energy needed to make the system operative. 

 "We must therefore look for the specific physical or chemical mech- 

 anisms which make possible the synthesis of peptide bonds." In 

 certain reactions they discuss, sparingly soluble compounds formed 

 crystallize out, and equilibrium conditions lead to further synthesis. 

 "In these peptide syntheses, therefore, the energy required for peptide 

 synthesis comes from the process of crystallization whereby the syn- 

 thetic product is removed from the equilibrium." In these cases 

 Bergmann and Fruton intimate that the kinetic energy (heat) set 

 free by the aggregation (crystallization) of the synthesized product, 

 is the mechanism whereby the energy is bandied about. The work 

 of Prof. Rudolf Schoenheimer 20 "led him to the view that in the 

 dynamic equilibrium between proteins and amino acids in the tis- 

 sues, peptide bonds are constantly being broken and reformed under 

 the catalytic influence of the tissue enzymes." 



In the ordinary microscope, fat globules in highly diluted milk 

 show an uneasy oscillation about a mean position. The ultra- 

 microscope reveals the violent Brownian motion of the colloidal 

 casein particles, whose swarming crowd can be seen jostling the 

 fat globules this way and that. But the more rapid kinetic motion 

 of the still smaller molecules of water and solutes is invisible, 

 though it underlies what we see and is also responsible for bring- 

 ing some molecules to a reactive state. Similarly, in the cell, the 

 unseen molecular activity greatly exceeds the intense activity of 

 particles made visible in the ultramicroscope. 



Professor F. G. Donnan of the University of London concisely 



