[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.