Stoichiometry of GTP breakdown during peptide synthesis on the ribosome. Stoichiometry of GTP hydrolysis during elongation of polyphenylalanine on polyuridylic acid

The stoichiometry of GTP hydrolysis during poly(Phe) elongation by Phe on poly(U) covalently bound to Sepharose was determined. The concentrations of both EF-T and EF-G were saturating. The GTP/Phe stoichiometry was calculated without the usual correction for the uncoupled ribosomal EF-T and EF-G dependent GTP hydrolysis. At the Mg2+ optimum (6 mM) for the poly(Phe) elongation on poly(U) . Sepharose the stoichiometry ratio of GTP/Phe was 1.9/2.1. This indicates that two (or less) GTP molecules coupled with poly(Phe) elongation by Phe on poly(U) . Sepharose are hydrolyzed.