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'Fluores cence Temperature Jump' in keywords Facet   Publication Year 1988  [X]
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1Author    W. Bujalowski, D. PorschkeRequires cookie*
 Title    Selective Binding of Amino Acid Residues to tRNA Molecules Detected by Anticodon-Anticodon Interactions  
 Abstract    Anticodon-anticodon pairing of complementary tRNA's has been studied by fluorescence tem-perature jump measurements in the presence of different ligands as an approach for the evalua-tion of ligand binding to tRNA. This procedure is particularly useful for ligands which do not show spectroscopic changes upon binding, but affect the pairing potential of anticodons. Addition of phenylalanine-, tyrosine-and tryptophan-amide leads to a substantial decrease of the tRNA Phe -tRNA Glu pairing constant K p , whereas K p remains almost unaffected by addition of leucine amide and increases upon addition of glycine amide. The effects observed for the aromatic amino acid amides can be described quantitatively by a site binding model with preferential binding of the amides to tRNA Phe . The binding constants evaluated according to this model (Phe-amide 120 M" 1 , Tyr-amide 160 M" 1 and Trp-amide 580 M~') are consistent with values obtained independently by fluorescence titrations with tRNA Phe . Selective binding of these amino acid residues to tRNA Phe is deduced from the observed concentration dependence, which is not com-patible with a corresponding binding process to tRNA Glu . Addition of glutamic acid diamide induces an increase of the tRN A Phe • tRNA Glu pairing constant, which is however equivalent to that observed for tRNA Phe -tRNA Lys pairing and thus does not demonstrate a selective binding to tRNA° lu . The pairing of tRNA Phe with tRNA Glu is strongly enhanced by addition of Mg 2+ or spermine. Evaluation of the Mg 2+ data by a site model leads to constants of 360 M~' for the binding of Mg 2+ to monomer tRNA and 3000 M" 1 for the binding of Mg 2+ to the tRNA Phe -tRNA Glu dimer. A comparison of the enhanced pairing observed in the presence of Mg 2+ , which is known to induce a 3'-stack conformation of the anticodon loop, with the reduced pairing affinity observed in the presence of aromatic amino acid amides suggests induction of a 5'-stack confor-mation by the latter ligands. 
  Reference    Z. Naturforsch. 43c, 91—98 (1988); received July 14 1987 
  Published    1988 
  Keywords    tRNA, Amino Acid Residues, Anticodon Binding, Protein Nucleic Acid Interactions, Fluores-cence Temperature Jump 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0091.pdf 
 Identifier    ZNC-1988-43c-0091 
 Volume    43