The Application of Fluorescent and Photosensitive Analogues of Guanine Nucleotides to the Function and Structure of G-Binding Proteins
In order to understand the mechanism of the interaction of a guanine nucleotide-binding protein at the molecular level it is necessary to determine the number of key intermediates of the process, to measure their rates of interconversion and ideally to gain structural information about the changes occurring during transitions between the intermediates. Our work has concentrated on defining the kinetic mechanism of elongation factor Tu (EF-Tu) on interaction with mRNA programmed ribosomes (Eccleston et al., 1985) and in the GTPase of p21N-ras (S.E. Neal, J.F. Eccleston, A. Hall, & M.R. Webb, unpublished results). These studies depended on measurements of GTP cleavage and, in the first case, peptide bond formation. However, these measurements at most give limited information about binding steps, protein isomerisations and dissociation steps which are essential features in the processes mediated by these GTPases. This information can be obtained by the use of spectroscopic probes which can be introduced into many different positions in the system.
KeywordsElongation Factor Guanine Nucleotide Nucleotide Binding Site Photoaffinity Label Isatoic Anhydride
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