A reactant is a substrate in a reaction, whereas a reagent is a catalyst. Regents can also be limiting. Limiting reagents stop a chemical reaction when they are used up.

The reagents use distance and geometry constraints to focus on specific target sites on substrates, like enzymes do. They coordinate reversibly with substrate molecules, derivatize them, detach ...

Enzymes are typically highly stereoselective catalysts that enforce a reactive conformation on their native substrates. We report here a rare example in which the substrate controls the ...