Inhibition of the assembly of cytochrome oxidase in Neurospora crassa by chloramphenicol.

Abstract

Cytochrome oxidase was prepared from Neurospora crassa by chromatography on oleyl poly‐methacrylic acid resin and separated into seven polypeptides by polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate. Incorporation of labelled amino acids into the single polypeptides was investigated after a pulse labelling in the absence and presence of chloramphenicol, and after washing out the inhibitor.Chloramphenicol (4 mg/ml) inhibited amino acid incorporation into all polypeptides 90–95% while labelling of the whole membrane protein was inhibited only 30%. After washing out the inhibitor and further growth of the cells, the four smaller polypeptides were highly labelled, whereas the other polypeptides showed only a small increase in radioactivity. It is concluded that the four small‐sized polypeptides of cytochrome oxidase are synthesized but not integrated into the functional enzyme under the action of chloramphenicol.