Studies on the Growth and Inhibition of Isolated Plant Parts. Iii. The Action of Some Inhibitors Concerned With Pyruvate Metabolism

THE EFFECT OF DINITROPHENOL AND OTHER INHIBITORS ON THE UPTAKE AND METABOLISM OF 2,4‐DICHLOROPHENOXYACETIC ACID BY CHLORELLA

“…Another known inhibitor of the TCA cycle, fluoroacetate (Bonner, 1949)' gives a quite different picture when supplied in combination with DNP. As is shown in Fig.…”

“…7, which shows that although a high concentration of fluoride is required to produce a pronounced effect, when the concentration does become sufficiently high (10-2 M), the effect of NaF tends to counteract the DNP effect, reducing the height of the peak at io-3 M DNP and raising the valley at io^^ M DNP. This ability of NaF to counteract the effects of DNP is assumed to stem from the inhibition of enolase by the fluoride (Bonner and Thimann, 1950) with the result that phosphoenol pyruvate formation is blocked and pyruvate synthesis prevented. This finding again supports the idea that the uptake of 2,4-D at high DNP concentrations comes about as a result of the increased supply of some substance subsequent to phosphoenol pyruvate in the metabolic scheme.…”