Sandbox Reserved 342: Difference between revisions
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The reaction catalyzed by XGPRT uses PRib-PP and a nitrogenous base to liberate a pyrophosphate and form a nucleoside monophosphate <ref name="Vos"/>. Magnesium and other divalent cations are necessary for catalysis because magnesium and PRib-PP binding play a critical role for the PRTase reaction<ref name="Vos"/>. The Mg:PRib-PP complex binds to the active site of PRTases<ref name="Vos"/>. XGPRT catalysis proceeds via SN1 mechanism and it forms a oxocarbonium ion in the transition state<ref name="Vos"/>. It has been suggested, that the magnesium ion departs with the displaced pyrophosphate because there is no magnesium ion at the active site, this has been determined by looking at crystal structures<ref name="Vos"/>. | The reaction catalyzed by XGPRT uses PRib-PP and a nitrogenous base to liberate a pyrophosphate and form a nucleoside monophosphate <ref name="Vos"/>. Magnesium and other divalent cations are necessary for catalysis because magnesium and PRib-PP binding play a critical role for the PRTase reaction<ref name="Vos"/>. The Mg:PRib-PP complex binds to the active site of PRTases<ref name="Vos"/>. XGPRT catalysis proceeds via SN1 mechanism and it forms a oxocarbonium ion in the transition state<ref name="Vos"/>. It has been suggested, that the magnesium ion departs with the displaced pyrophosphate because there is no magnesium ion at the active site, this has been determined by looking at crystal structures<ref name="Vos"/>. | ||
In the <scene name='Sandbox_Reserved_342/Mobile_loop/1'>mobile loop</scene> (shown in red) of the XGPRT, there are several residues that are critical for substrate and catalysis<ref name="Vos"/>. The loop required for binding and catalysis is flexible, when XGPRT does not have products or substrates bound to it<ref name="Vos"/>. The flexibility of the residues in this loop assists movement of the loop towards the active site<ref name="Vos"/>. | In the <scene name='Sandbox_Reserved_342/Mobile_loop/1'>mobile loop</scene> (shown in red) of the XGPRT, there are several residues that are critical for substrate and catalysis<ref name="Vos"/>. The loop required for binding and catalysis is flexible, when XGPRT does not have products or substrates bound to it<ref name="Vos"/>. The flexibility of the residues in this loop assists movement of the loop towards the active site<ref name="Vos"/>. An additional role of the mobile loop is to cover the active site during catalysis to prevent water molecules from capturing the transition state intermediate <ref name="Vos"/>. | ||
In XGPRT, the purine base selectivity is achieved by side-chain interactions <ref name="Vos"/>. | |||
=Additional Resources= | =Additional Resources= | ||