Final answer:
Non-compatible substrates cannot bind to the enzyme's active site due to the specific shapes required for binding. Non-competitive inhibitors alter the enzyme's shape in a different location, affecting the active site indirectly, while competitive inhibitors block the active site directly.
Step-by-step explanation:
Non-compatible substrates are unable to bind with the enzyme's active site due to the specificity of the active site's shape and the molecular structure of the substrates. Enzymes work based on two main models: the lock-and-key hypothesis and the induced fit hypothesis. Both models highlight how the active site of an enzyme is not completely malleable and requires a particular substrate shape for binding.
In the case of non-competitive inhibition, an inhibitor binds to a different site on the enzyme which causes an allosteric change, altering the enzyme's shape. This change prevents the proper binding of the substrate to the active site, leading to a decrease in enzyme activity.
In contrast to non-competitive inhibitors, competitive inhibitors bind directly to the active site, competing with the substrate for access to the enzyme's active site, thus preventing the formation of enzyme-substrate complexes.