Occurrence of the Crabtree effect in HeLa cells

The occurrence of a Crabtree effect in HeLa cells was detected. Some properties of pyruvate kinase (PK) were also evaluated. Hexose phosphate, triose‐phosphate and phosphoenolpyruvate (PEP) significantly decreased the oxygen consumption of digitonin‐permeabilized HeLa cells, which were oxidizing succinate. The Crabtree effect promoted by PEP was concentration‐dependent and was lowered by an increase of ADP concentration, suggesting a participation of PK. The dependence of fructose‐1,6‐bisphosphate (FDP) by HeLa cell PK was observed. The PK of HeLa cells was inhibited by L‐alanine only in the absence of FDP, while in the presence of the metabolite, an increase in the activity was observed. PK was also inhibited in the presence of L‐histidine and L‐leucine, while L‐serine promoted activation. L‐Cysteine and L‐phenylalanine also inhibited the PK of HeLa cells. This, together with the sigmoidal character in relation to substrate concentration, suggests the presence of the K‐type of PK in HeLa cells. © 1998 John Wiley & Sons, Ltd.