The leadzyme is a minimal catalytic motif derived from in vitro selection. It consists of a duplex with a three-base bulge. In crystals, it adopts two discrete conformations that differ in their metal-binding properties. These two conformations presumably represent a ground state and a precatalytic state of the molecule.
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Nat Struct Biol. 6, 261-268.
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"Crystal structure of the leadzyme at 1.8 A resolution: metal ion binding and the implications for catalytic mechanism and allo site ion regulation"
Biochemistry 42, 9554-9563.
[Mg(2+) + Sr(2+) coordinates]