title: Purification and characterization of a ribosome dissociation factor (eukaryotic initiation factor 6) from wheat germ.
abstract: A wheat germ ribosome dissociation factor, eukaryotic initiation factor 6 (eIF-6), has been purified almost to homogeneity from the 25 to 40% ammonium sulfate fraction of the postribosomal supernatant. This dissociation factor is distinct from initiation factor eIF-3 and its chromatographic properties permit its separation from the known wheat germ initiation factors. Under certain conditions, eIF-6 stimulates the incorporation of amino acids into polypeptides in a partially fractionated wheat germ cell-free system. The eight-step purification procedure developed includes chromatography on DEAE-cellulose, phosphocellulose, Sephadex G-75, and hydroxyapatite and yields a dissociation factor more than 80% pure. The purified factor is composed of a single polypeptide chain with a molecular weight of approximately 23,000 as determined by gel filtration chromatography and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It is an acidic protein which is heat labile and is inactivated by treatment with N-ethylmaleimide. The dissociation factor is much more effective in preventing the reassociation of 40 S and 60 S ribosomal subunits than in directly dissociating 80 S ribosomes. Like Escherichia coli IF-3, about 10 pmol of the dissociation factor are required to dissociate 1 pmol of ribosomes.
mesh_terms: D005033:Ethylmaleimide / Q000494:pharmacology; D007700:Kinetics; D008970:Molecular Weight; D010448:Peptide Initiation Factors / Q000302:isolation & purification* / Q000378:metabolism; D010944:Plants / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D014908:Triticum / Q000378:metabolism
chemical_list: D010448:Peptide Initiation Factors; D012333:RNA, Messenger; C021019:eIF-6; D005033:Ethylmaleimide