Effet inhibiteur de Zn2+ sur la biosynthese induite par l'oxygene des enzymes respiratoires de la levure

To investigate what the function might be of the Zn-protoporphyrin present in yeast cells, the course of the O₂-induced biosynthesis of respiratory enzymes was studied in yeast harvested from anaerobic culture on synthetic medium, either with Zn²⁺ added at a concentration which stimulates the growth ((+) Zn yeast) or without added Zn²⁺ ((−) Zn yeast).

Zn²⁺ has an inhibitory effect of the respiratory adaptation. In (−) Zn yeast, the adaptive development of respiratory enzymes is much faster; there is an increase of cytochrome content, O₂ consumption, succinate: cytochrome c reductase and NADH₂: cytochrome c reductase activities and a decrease of fermentation.

Different hypotheses are presented to explain the inhibitory effect of Zn²⁺ on the synthesis of respiratory enzymes.