Chloramphenicol as an Energy Transfer Inhibitor in Spinach Chloroplasts

At concentrations of up to 300 mug/ml both d-threo- and l-threo-chloramphenicol act as energy transfer inhibitors in spinach chloroplasts, in that they inhibit both phosphorylation and phosphorylating electron transport, without affecting the nonphosphorylating electron transport which occurs either in the absence of a phosphate acceptor or in the presence of the uncoupler ammonium chloride. At higher concentrations, there appears to be an additional site of chloramphenicol inhibition of electron transport. If d-threo-chloramphenicol is to be used as a protein synthesis inhibitor in intact chloroplasts or tissues, control experiments with another chloramphenicol isomer seem to be necessary.