Control of Stereoselectivity in an Enzymatic Reaction by Backdoor Access

摘要

The ability of biopolymers to discriminate between optical isomers is vital for living systems, and the selective formation of only one product stereoisomer from achiral substrates is one of the most sophisticated tasks for enzymes. Using a Diels-Alder ribozyme as an example, we demonstrate here that by a simple strategy a biocatalyst can be used to selectively synthesize both product stereoisomers in one catalytic pocket, namely, by controlling access to the active site from opposite directions through different doors. While substrates tethered to the catalyst were used to observe this phenomenon, we propose that nature may use conformational gating to control the stereoselectivity of enzymatic reactions.