CONVENTIONS 



The effects of inhibitors on enzyme activity, metabolism, or tissue function are 

 expressed as fractional inhibitions, designated by the symbol i. This is the fraction of 

 the total control activity that is inhibited under the conditions specified and thus may 

 vary from zero to unity. The various ways in the literature of expressing inhibition 

 have all been reduced to this convention and liberty has frequently been taken to cal- 

 culate fractional inhibitions from untreated data. It is hoped that such a standard 

 system will allow comparisons to be made readily. The kinetic equations are also ex- 

 pressed in terms of the fractional inhibition. 



Rate constants are always expressed by the lower case k and equilibrium constants 

 by the upper case K. The subscripts for the rate constants are positive or negative 

 depending on the direction of the reaction; thus, for the reaction A ^.B, k^ is the rate 

 constant for the reaction of A to B and i'.i is the rate constant for the reverse reaction. 

 The subscript number indicates the step in a sequence of reactions. A' always refers 

 to a dissociation constant and thus is the inverse of the corresponding association 

 constant; for example, for the reaction A + B ;:± AB, the value of K is given by 

 (A) (B)/(AB). 



Concentrations of substrates and inhibitors are generally given as millimolar {n\M), 

 as are the dissociation constants, for the purpose of establishing a uniform system. 



The enzyme nomenclature attempts to follow Table V. 1 of Dixon and Webb (" En- 

 zymes," 1958) wherever possible. 



SYMBOLS 



The most commonly used symbols are defined in the following list. Other symbols 

 of more restricted use are described in the text where they occur. Where the same 

 symbol is applied to two or more different functions, there should be no confusion 

 in the contexts in which the symbols appear. 



a fractional activity (enzymic) A constant for attraction energy 



a activity (thermodynamic) AR agonist-receptor complex 



A activator B constant for repulsion energy 



A agonist d distance between interacting 



A antibody particles 



xni 



