FIG. 4.

The DFA scores (1 to 3) from the analysis illustrated in Fig. 3 were averaged according to compound (i.e., scores for the members of each class were averaged) and subjected to HCA. A separation of the respiratory and nonrespiratory inhibitors was observed in the resulting dendrogram. Fluazinam (marked with an asterisk) is cited as an uncoupler of oxidative phosphorylation (17), and although it might conceivably be regarded as a respiratory inhibitor, it is not, of course, a respiratory chain inhibitor, and the level of inhibition it induces in cells growing on a fermentable carbon source is too great to arise from the inhibition of respiration-coupled processes alone; and therefore, this compound must inhibit other reactions within the cell, most likely on some proton-coupled uptake process necessary for fermentative growth.