LIFESCI 3 Chapter Notes - Chapter 18.4: Aminoacyl-Trna, World Federation Of Trade Unions, Peptidyl Transferase
Document Summary
18. 4 elongation and termination of the polypeptide chain. Elongation: nascent polypeptide is lengthened by covalent attachment of amino acids. Termination: signalled by one of three stop codons. Ribosomes are recycled for another round of translation. Peptide bonds are formed in the translation elongation stage. Incoming aminoacyl-trna binds to a complex of gtp bound ef-tu then the a site. Gtp is hydrolyzed and ef-tu-gdp complex is released. Ef-tu-gtp complex is regenerated sing ef-ts and gtp. When ef-tu-gdp releases the aminoacyl end it is still far from the active site. Accomodation: correct codon-anticodon interactions rotate trna into position for rxn. Substrate positioning and the incoming trna contribute to peptide bond formation. Peptide bond is formed between 2 amino acids bound by their trnas to the a and p site. Transfer n-formylmethionyl group from trna in p site to amino group of the second amino acid on its trna in the a site.
