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  • Title: Interactions of elongation factor 2 (EF-2) with guanine nucleotides and ribosomes. Binding of periodate-oxidized guanine nucleotides to EF-2.
    Author: Nurten R, Bermek E.
    Journal: Eur J Biochem; 1980 Feb; 103(3):551-5. PubMed ID: 6244163.
    Abstract:
    Interactions of rat liver elongation factor 2 (EF-2) with guanine nucleotides and ribosomes were studied by equilibrium dialysis and sedimentation methods. GDP (Kd = 0.5 microM) or GDP-Mg2+ (Kd = 1.57 microM) displayed a higher affinity in the formation of a binary complex with EF-2 than GTP (Kd = 2.68 microM), GTP-Mg2+ (Kd = 2.77 microM), or guanosine 5'-[beta, gamma-methylene]triphosphate (GuoPP[CH2]P) (Kd = 24.0 microM). NaIO4-oxidized guanine nucleotides (oGDP) (Kd = 38 microM) and oxidized/reduced guanine nucleotides (orGDP) (Kd = 27 microM) had lower affinites to the binding site on EF-2 than those of GDP or GTP. However, the binding of oGDP, oGTP or oGuoPP[CH2]P to EF-2 resulted in the formation of a stable product which could be recovered by the nitrocellulose filter technique or by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. In the presence of ribosomes and EF-2 the formation of a new binding site (or a different conformation of the binding site) with a higher affinity for GuoPP[CH2]P-Mg2+ (Kd = 0.26 microM) than fof GDP-Mg2+ (kd = 9.3 microM) became apparent. The presence of ribosomes thus appeared to favor the formation of a complex involving guanosine triphosphates. Adenosine diphosphate ribosylated EF-2 (ADP-Rib-EF-2) in its turn could bind to the ribosome with high affinity even without guanosine nucleotides (Kd = 0.18 microM). GuoPP[CH2]P increased to some extent the affinity of ADP-Rib-EF-2 for its ribosomal binding site (Kd = 0.05 microM).
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