CHAPTER IV 



INFLUENCE OF OTHER FACTORS UPON ENZYMES AND CELLS 

 TEMPERATURE PHYSICAL AND CHEMICAL AGENTS- 

 NEGATIVE CATALYSTS, ANTI-CATALYSTS, ANTI-FERMENTS, 

 AND ANTI-ENZYMES ZYMO-EXCITATORS OR KINASES 

 AUTO-CATALYSIS AND INFECTION SPECIFIC NATURE 

 OF CATALYTIC ACTION THE CHEMICAL AND PHYSICAL 

 NATURE OF ENZYMES THE SO-CALLED INORGANIC 

 ENZYMES OR METAL-SOLS 



IT is characteristic of all enzymes that they are very sensitive to 

 changes of temperature both as regards their stability and as 

 regards their rapidity of action. 



The stability of the different enzymes varies very widely, 

 but as a general rule it may be stated that the rate of destruction 

 rapidly increases with the temperature, although this may lie 

 much below that at which they are most rapidly destroyed. The 

 amount of enzyme destroyed also varies with the substances 

 present in solution ; thus the products of reaction in all cases 

 exercise a protective action against rise in temperature which has 

 been ascribed to the formation of a compound between the enzyme 

 and the products of its activity. 



All enzymes in aqueous solution are rapidly destroyed at about 

 the coagulation temperature of proteids (65-75 C.), and a coagulum 

 usually appears in the solution. 



Even at body temperature and below it many are, however, 

 rapidly destroyed, especially in the absence of a protective sub- 

 stratum. Thus Vernon has shown that trypsin in nearly pure 

 solution is rapidly destroyed at 38 C., but is protected from such 

 rapid destruction by the presence of proteid. The subject has 

 been further investigated by Bayliss, who finds that trypsin in 

 solution loses activity even at C. 



The action of heat upon enzymes in organic solvents is much 

 less marked than in aqueous solutions ; thus Pavy finds that 



