title: Modification of amino groups in EF-Tu.GTP and the ternary complex EF-Tu.GTP.valyl-tRNAVal.
abstract: In an attempt to describe the binding region of EF-Tu . GTP for aminoacyl-tRNA, the epsilon-amino groups of the lysine residues of the protein molecule in the GTP and ternary complexes were modified with ethyl acetimidate. Using [14C]ethyl acetimidate, tryptic digestion, fractionation of peptides by high-performance liquid chromatography, and amino acid analysis, all reactive lysine residues could be unambiguously identified. 19 of the 23 lysine residues of EF-Tu were labelled under conditions for ternary complex stability. Of these only 8 showed differences in reactivity between free and complexed EF-Tu . GTP. In the ternary complex lysine residues 208 and 390 [Jones, M. D., Petersen, T. E., Nielsen, K. M., Magnusson, S., Sotterup-Jensen, L., Gausing, K. and Clark, B. F. C. (1980) Eur. J. Biochem. 108, 507-526] showed an increase in reactivity (60% and 30% respectively) and residues 2, 4, 237, 248, 263, and 282 showed a decrease in reactivity (between 85% and 37%) compared to the values observed with EF-Tu . GTP. The greatest changes in reactivity were observed for lysine residues 2, 4 and 263. These data can be combined with the available structural information to identify possible areas of contact between the protein and nucleic acid moieties in the ternary complex.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006160:Guanosine Triphosphate / Q000378:metabolism*; D007096:Imidoesters; D008239:Lysine / Q000032:analysis; D010444:Peptide Elongation Factor Tu; D010445:Peptide Elongation Factors / Q000378:metabolism*; D010446:Peptide Fragments; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism*; D014357:Trypsin
chemical_list: D000596:Amino Acids; D007096:Imidoesters; D010445:Peptide Elongation Factors; D010446:Peptide Fragments; D012346:RNA, Transfer, Amino Acyl; C014539:ethyl acetimidate; D006160:Guanosine Triphosphate; D014357:Trypsin; D010444:Peptide Elongation Factor Tu; D008239:Lysine