title: Mitochondrial protein synthesis in Plasmodium falciparum.
abstract: Protein synthesis in intact Plasmodium falciparum was 333 times more sensitive to cycloheximide than to chloramphenicol. The 50% inhibitory concentration (IC50) of cycloheximide in a 27-h assay in vitro was 6 X 10(-7) M but no constant cycloheximide-insensitive fraction of total protein synthesis was observed at concentrations of this inhibitor between 10(-7) and 10(-2) M. 0.24% of total protein synthesis occurred in the presence of 10(-3) M cycloheximide but the chloramphenicol sensitivity of this fraction was similar to that of overall protein synthesis (IC50 2 X 10(-4) M). The major fraction of protein synthesis by P. falciparum, therefore, is assumed to be cytoplasmic and to occur on 80S ribosomes. Cycloheximide-insensitive, chloramphenicol-sensitive (70S ribosomal) protein synthesis being undetectable by the methods employed, mitochondrial protein synthesis in P. falciparum is presumed to constitute a considerably smaller fraction of the total protein synthetic capacity than observed in other lower eukaryotes.
mesh_terms: D000818:Animals; D002701:Chloramphenicol / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D007532:Isoleucine / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D010963:Plasmodium falciparum / Q000378:metabolism* / Q000648:ultrastructure; D014176:Protein Biosynthesis; D012270:Ribosomes / Q000378:metabolism
chemical_list: D007532:Isoleucine; D002701:Chloramphenicol; D003513:Cycloheximide