METHODS

When insulin is added to antiserum, the insulin and antibody molecules combine with each other to form insulin-antibody complexes, the rate of combination depending on the concentrations of the reactants and the activation energy of the reaction. Since the reaction is reversible, 1"* the formed complexes continually undergo dissociation into free insulin and free antibody molecules. After a period of time, equilibrium is reached, ie, the number of complexes being formed just equals the number of complexes undergoing dissociation, and the ratio of insulin bound in complexes to free insulin (denoted by B/F) remains constant thereafter. In mixtures in which the concentration of insulin is very low compared to the concentration of antibody molecules, there are always many uncomplexed antibody molecules readily available for reaction with the few insulin molecules and B/F is higher than in mixtures in which the insulin concentration is such that there is no marked excess of