2000
DOI: 10.1046/j.1365-2443.2000.00352.x
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Abstract: Background: Several reports have appeared recently of experimental evidence for a double-metal-ion mechanism of catalysis in reactions catalysed by hammerhead ribozymes. In one case, hammerhead ribozyme-mediated cleavage was analysed as a function of the concentration of La 3 ions in the presence of a ®xed concentration of Mg 2 ions so that the role of metal ions that are directly involved in the cleavage reaction could be monitored. The resultant bell-shaped curve for activation of cleavage was used to suppor… Show more

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Cited by 22 publications
(32 citation statements)
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“…26 Since then, additional experimental evidence has accumulated in favor of a two-metal-ion mechanism. [27][28][29][30] The two-metal-ion mechanism is strongly supported by the differential metal-ion effects on the cleavage rate observed for the natural substrate (cleavage activation observed in the presence of Mg 2+ and La 3+ ) 28,30 and for a 5′ thio modified substrate. 27 The metal ions usually involved in chemical catalysis are divalent cations such as Mg 2+ or Mn 2+ .…”
Section: Introductionmentioning
confidence: 91%
“…26 Since then, additional experimental evidence has accumulated in favor of a two-metal-ion mechanism. [27][28][29][30] The two-metal-ion mechanism is strongly supported by the differential metal-ion effects on the cleavage rate observed for the natural substrate (cleavage activation observed in the presence of Mg 2+ and La 3+ ) 28,30 and for a 5′ thio modified substrate. 27 The metal ions usually involved in chemical catalysis are divalent cations such as Mg 2+ or Mn 2+ .…”
Section: Introductionmentioning
confidence: 91%
“…The most recent structural and functional studies also identify a Mn 2+ ion with the same G33:N7 direct coordination, and report that G33(7cG) mutation leads to a 1.3 × 10 4 -fold decrease in rate (Wilson et al 2019). This differs considerably from the 30-fold effect of G10.1(7cG) mutation in HHr (Nakamatsu et al 2000). While this binding mode is likely important for Mg 2+ , it is noteworthy that Psr retains modest activity in the presence of the exchange-inert cobalt hexammine as the sole multivalent cation (Harris et al 2015).…”
Section: The Role Of Mg 2+ Ions In β and δ Catalysis Subtly Differs In Psr And Hhrmentioning
confidence: 97%
“…The transesterification mechanism includes deprotonation of the 2 0 -hydroxyl moiety of a ribose group, nucleophilic attack of the 2 0 -oxygen on the adjacent phosphorus atom, and protonation of the 5 0 -oxyanion leaving group ( Figure 1A). A large body of evidence also indicates that the P9/G 10.1 site binds a metal ion with high affinity, with other metal ion-binding sites being located around the G 5 nucleobase and A 13 phosphate near the site of cleavage (23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36). Thus, the idea that ribozymes are metalloenzymes has been generally accepted.…”
Section: Introductionmentioning
confidence: 99%
“…This finding raises the possibility that hammerhead ribozymes should not be classified as metalloenzymes. Therefore, we decided to investigate ribozyme activity in the presence of Mg 2+ ions and the effects of Mg 2+ ions in the presence of Li + ions on ribozyme activity, using a well-studied model hammerhead ribozyme (R32) and its substrate (S11), both of which are shown in Figure 1B (5)(6)(7)25,28,(32)(33)(34)(38)(39)(40)(41).…”
Section: Introductionmentioning
confidence: 99%