The GTP analog guanylyl-methylene-diphosphonate has a methylene group replacing the oxygen between the β and γ phosphorus atoms, thus preventing enzymic cleavage at this position (Fig. 61). The structure of this analog has been designed to test the nature of the reactions involving GTP hydrolysis in protein synthesis. Since the GTP analog was first shown to block polyphenylalanine synthesis (Hershey and Monro, 1966), it has been used repeatedly in studies on protein synthesis in the different steps of the initiation, elongation and termination phases in which GTP hydrolysis is involved. The GTP analog guanylyl-imido-diphosphate has also been synthesized to study the role of GTP in translocation (Eckstein, Kettler and Parmeggiani, 1971). Studies with GDP and GTP analogs have concluded that a common or overlapping ribosomal site is involved in the interaction of protein translation factors required for GTP hydrolysis (Modolell and Vázquez, 1975, review).
KeywordsPhosphorus Atom Enzymic Cleavage Fast Release Termination Phase Acceptor Substrate
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