title: Different conformations of nascent peptides on ribosomes.
abstract: The length at which the N terminus of nascent proteins becomes available to antibodies during their synthesis on ribosomes was determined. Three different proteins, bovine rhodanese, bacterial chloramphenicol acetyltransferase and MS2 coat protein, were synthesized with coumarin at their N terminus in a cell-free system derived from Escherichia coli. A derivative of coumarin was cotranslationally incorporated as N-coumarin-methionine at the N terminus of polypeptides. The interaction of specific anti-coumarin antibodies with this N-terminal coumarin of ribosome-bound nascent peptides was examined. The results indicate that short nascent peptides of each of the three proteins are unreactive, that the length at which they become accessible to the antibodies is different for the three proteins, and that longer peptides differ in their reactivity. It is suggested that these differences are due to differences in the conformation acquired by the peptides as they are synthesized on the ribosomes.
authors.affiliation: Department of Chemistry and Biochemistry, University of Texas, Austin 78712, USA.
authors.forename: T
authors.initials: T
authors.lastname: Tsalkova
authors.forename: O W
authors.initials: OW
authors.lastname: Odom
authors.forename: G
authors.initials: G
authors.lastname: Kramer
authors.forename: B
authors.initials: B
authors.lastname: Hardesty
mesh_terms: D002213:Capsid / Q000096:biosynthesis; D036022:Capsid Proteins; D002474:Cell-Free System; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D002850:Chromatography, Gel; D003374:Coumarins / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D010441:Peptide Chain Elongation, Translational; D010442:Peptide Chain Initiation, Translational; D010455:Peptides / Q000737:chemistry*; D011233:Precipitin Tests; D014176:Protein Biosynthesis; D011487:Protein Conformation; D017510:Protein Folding; D016601:RNA-Binding Proteins / Q000096:biosynthesis; D012270:Ribosomes / Q000737:chemistry* / Q000378:metabolism; D013884:Thiosulfate Sulfurtransferase / Q000096:biosynthesis
chemical_list: C112645:CPM methionine; D036022:Capsid Proteins; D003374:Coumarins; D005456:Fluorescent Dyes; C112644:N-coumarin-methionine; D010455:Peptides; D016601:RNA-Binding Proteins; C030860:N-(4-(7-diethylamino-4-methylcoumarin-3-yl)phenyl)maleimide; D015500:Chloramphenicol O-Acetyltransferase; D013884:Thiosulfate Sulfurtransferase