102 OXIDATION-REDUCTION POTENTIALS 



moving at high speed in different directions in his factory and even flying out of the 

 door and windows. 



Continuing to follow the glucose molecule : it will be anchored temporarily to 

 the phosphorylating enzyme and perhaps the phosphate group and free energy of a 

 molecule of adenosine triphosphate from the cytoplasmic interior will be utilised ; 

 then the glucose-6-phosphate is released by the enzyme and is attached by a neigh- 

 bouring phosphohexose isomerase enzyme system. Thus the metabolite will pass 

 along the series of enzyme systems until there is no appropriate enzyme system active 

 enough to anchor it and transform its molecule further. Then the lactate or other 

 product will be ejected from the cell, having again to traverse the cell wall and capsule. 

 The whole of this process has to be repeated a million times a minute by each bacterial 

 cell. 



Although the hypothetical breakdown of a glucose molecule has been traced , the 

 same considerations apply to nitrogen metabolism. During the logarithmic growth 

 phase when the cells are re-synthesising themselves as frequently as every twenty 

 minutes the complicated processes of specific protein synthesis have to be effected, 

 and also that of the nucleic acids which are perhaps the directors and organisers of 

 specific synthesis. 



Again oxidation-reduction reactions effected by the cell are dependent upon 

 oxidants being brought into contact with the necessary dehydrogenases, oxidases, etc., 

 and their coenzymes, and dependent also upon the reduced substances being present 

 to maintain electrode balance. 



The importance of maintaining the reactants in a complex enzyme substrate 

 system in close contact is emphasised by experiments of Keihn and Hartree (1949) 

 who found that the presence of denatured proteins and of gelatinous precipitates 

 formed on addition of various metallic salts activated the succinic dehydrogenase- 

 cytochrome system. It is suggested therefore that various additions such as proteins 

 and metal salts may affect an enzyme system quite non-specifically causing activa- 

 tions and inhibitions which might, quite erroneously, be ascribed to effects on essential 

 Unks in the catalytic chain. Caution in the interpretation of results is therefore 

 necessary and it would be well to re-examine a number of phenomena in the light of 

 this suggestion. It is natural to ascribe all effects to specific catalytic reactions, whereas 

 the " colloidal state " of the system will effect the contiguity of the components and 

 hence their ability to react. Especially is this true of bacterial systems where diffu- 

 sion of reactants from the immediate vicinity of the cell to relatively enormous 

 distances away in the culture medium will remove them from effective co-operation 

 in the cell's economy. 



The nature of the antigenic complex occurring at the surface of the Shiga 

 dysentery bacillus is indicated by the possibility of dissociating the polysaccharide- 

 lipide-protein complex and then recombining the components to form a complete 

 antigen (Morgan and Partridge, 1941). 



BACTERIAL REDUCTIONS 



At the risk of repetition it is necessary to emphasise the necessity to avoid 

 confusing symptoms and functions. The development of reducing conditions in 

 bacterial cultures is a symptom of the dynamic equilibrium, which is always in a 

 state of change. In a bacterial culture, unlike a tissue cell's environment, there is not 



