At any given time, these can be disrupted by small changes in their vicinity. The approach of the substrate is viewed as such a perturbation. The enzyme and substrate must still have complementary surfaces. Many enzymes are group specific , that is, they will bind and catalyze a reaction for a whole family of related compounds. Others are linkage specific , that is, they catalyze the formation or breakage of only certain bonds, the hydrolysis of peptide bonds for example.
Many enzymes are even stereo specific .
These enzymes, because they are themselves chiral, can only bind one of a pair of enantiomers, and form only one of two possible enantiomeric products. How does the formation of the ES complex result in faster chemical reactions. The answer to this probably varies with every enzyme. In fact, we only understand the exact mechanism of catalysis for a handful of enzymes. But, there are general features of enzyme-substrate interactions that result in enhanced reaction rates.