Enzymatic synthesis of isopentenyl pyrophosphate in sweet potato root tissue in response to infection by black rot fungus1

摘要

Cell-free systems were prepared from fresh, cut and black rot-diseased tissues of sweet potato roots. When incubated in the presence of mevalonate, all these systems were capable of synthesizing 5-phosphomevalonate, mevalonate-5-pyrophosphate and isopentenyl pyrophosphate. The time courses for the appearance of the14C-labeled metabolites suggested the following order of synthesis: mevalonate→5-phosphomevalonate→mevalonate-5-pyrophosphate→isopentenyl pyrophosphate. It was also shown; on prolonged incubation, that isopentenyl pyrophosphate was converted slowly to isopentenyl monophosphate. The activity for synthesis of isopentenyl pyrophosphate from mevalonate was higher in diseased tissue than in cut and healthy ti