F. Charalampous
Feb 25, 1974
Citations
0
Influential Citations
13
Citations
Quality indicators
Journal
The Journal of biological chemistry
Abstract
Abstract Coproporphyrin III was isolated from aerobically and anaerobically grown yeast and from the medium of anaerobic cultures, and was identified as the compound responsible for the inhibition of the synthesis de novo of apocytochrome oxidase in yeast protoplasts. Authentic coproporphyrin III gives identical results. The intracellular concentration of coproporphyrin above which all synthesis of the oxidase ceases is 0.26 ± 0.013 µm. The coproporphyrin concentration in anaerobic and aerobic yeast is 0.4 and 0.15 µm, respectively. The inhibitory action of coproporphyrin is observed only when the yeast protoplasts are incubated anaerobically. Oxygen prevents and reverses this inhibition. With the aid of cycloheximide, chloramphenicol, and acriflavin it was shown that coproporphyrin inhibits mitochondrial transcriptional, but not translational, events involved in the synthesis of cytochrome oxidase, as well as the synthesis of the polypeptides translated on cytoplasmic ribosomes. Coproporphyrin has no effect on the assembly of the holoenzyme from its polypeptides and heme a. It is concluded that oxygen regulates the synthesis of cytochrome oxidase by acting as cosubstrate in heme a synthesis and by abolishing the inhibition by coproporphyrin of the synthesis of apocytochrome oxidase.