RAPID METHOD FOR SCREENING INHIBITOR EFFECTS - DETERMINATION OF I50 AND ITS STANDARD DEVIATION

A simple method has been developed for the rapid screening of potential effectors on enzymatic reactions. Use is made of the linear relationship between the inhibitor concentration I and the corresponding value I (I - P), where P is the fraction of inhibition given by I. This mode of representation permits the evaluation of half-inhibitory doses (I50) and the calculation of their standard deviations SI. Theoretically, these parameters can be determined from the results of measurements carried out at a single inhibitor concentration. The method proved useful when applied to the study of a number of potential effectors of adrenal cortex cyclic AMP phosphodiesterase activity. This model system was used to assess the advantages and limitations of the procedure. This approach should be of value when dealing with the usual types of enzyme inhibition mechanisms and may be of interest in other biochemical fields, such as in the study of hormone-receptor interaction, provided that the biological and statistical limitations of the method are not overlooked. © 1978.