QUASI-IRREVERSIBLE INHIBITION OF ENOLASE OF STREPTOCOCCUS-MUTANS BY FLUORIDE

Fluoride at concentrations greater than 0.01 mM was found to be a quas i-irreversible inhibitor of enolase of permeabilized cells of Streptoc occus mutans GS-5 and also of isolated yeast enolase. The inhibition a ppeared to be of the type that has been described for P-ATPases, but w as not dependent on added Al3+ or Be2+ ions. Fluoride inhibition of en olase was not reversed by repeatedly washing the permeabilized cells i n chilled fluoride-free medium but could be reversed by the product, p hosphoenolpyruvate, or by very high levels of the substrate, 2-phospho glycerate. Irreversible inhibition of glycolysis was not evident after fluoride treatment of intact cells, washing to remove unbound or loos ely bound fluoride and addition of glucose, presumably because intrace llular levels of phosphoenolpyruvate were sufficiently high to preclud e irreversible fluoride inhibition of enolase.