Derepression of glyoxylate cycle enzyme activities in anise suspension culture cells

Abstract

In cells of suspension cultures of anise ( Pimpinella anisum L.) the key enzymes for the glyoxylate cycle, isocitrate lyase and malate synthase, are active only when the growth medium lacks any source of carbon. They appear after a lag phase of about 20 h during which over 60% of the cell's starch is degraded and reach maximum activity after about 48 h. Addition of 20 mmol/l acetate induces doubling of the level of enzyme activities but only when sucrose is absent from the medium. The effect of acetate is, over the range of 1–20 mmol/l, essentially independent of the dose added. Also, derepression is not affected by the phase of growth of the cultures used. It is concluded that similar to fungal cells the level of glycolytic metabolites is involved in enzyme derepression through yet unknown mechanisms.