4 INFLUENCE OF TEMPERATUKE ON BIOLOGICAL SYSTEMS 



was previously a racemic world suddenly becomes and remains optically 

 active. 



APPLICATION OF REACTION RATE THEORY 



It has frequently been argued that a critical complex such as our theory 

 requires is too comjjlicated to have arisen within the framework of known 

 physical and chemical laws. An examination of this situation apparently 

 leads to a different conclusion. 



The most probable rate of appearance of our critical complex like 

 other reactions is governed by the well known theory of absolute reaction 

 rates. As for any reaction, we can write, 



dc/dt =CiC2 ••• c„K(kT/h)e-(^^^'^^' U) 



Here dc/dt is the most probable rate for the appearance of our critical 

 complex; Ci to Cn are the concentrations of the respective reactants; k is 

 the transmission coefficient which we may here suppose to be unity ; kT/h, 

 which has the value 5.6 X 10^-, at 300° absolute is the frequency of reac- 

 tion of the activated complex whose concentration is governed by the 

 equilibrium constant 



AFJ is, of course, the free energy of activation and k, T, h and R are the 

 Boltzmann constant, the absolute temperature, Planck's constant and the 

 gas constant, respectively. 



Equation 1 may for our purpose be more conveniently written as, 



dn/dt = nico ••• c„,(kT/h)e-(^^t'^''\ [2) 



Here we have simply changed from the concentrations, Ci , of this reactant 

 to the total number of such reactants, Ui along with the necessary ac- 

 companying change over from dc/dt to the total number of critical com- 

 plexes formed per second, dn/dt. Now in discussing 2 we will be obliged 

 to introduce very crude estimates. These will, however, illustrate the kind 

 of additional information required and, therefore, what experiments should 

 be done, as well as the degree of overall reasonableness of the critical com- 

 plex theory. We estimate all concentrations at 1/1000 molal. We assume 

 next that m reactants join in a line to form the critical complex. Of the 

 m-1 bonds so formed, we assume m-2 contribute factors of 1/lOOth each 

 to K| and that the final bond contributes the factor g-^^cooo/rt) ^^ kJ 

 as the last bond passes over the potential barrier corresponding to the 

 activated complex. A factor of 1/1 00th for a bond corresponds to a con- 

 tribution to AF* of +2.6 kilo calories, which is about the degree of insta- 

 bility assigned peptide bonds, for example (6). Contact stabilization by 



