Summary
Highlights
Living cells require countless chemical reactions to function, but these reactions are often slow. Increasing temperature to speed them up is not feasible due to energy requirements, potential cell damage, and the acceleration of unwanted reactions. Catalysts, particularly biological catalysts called enzymes, offer a better solution to accelerate reactions without being consumed in the process.
Enzymes are a specific type of catalyst produced by living organisms; they are large proteins made of amino acid chains. The unique sequence of these amino acids causes enzymes to fold into distinct shapes, with each unique shape catalyzing a particular chemical reaction.
Enzymes speed up chemical reactions by converting substrates into products. They possess a specialized region called an active site, which has a unique shape complementary to the specific substrates of the reaction. This specificity ensures that only certain reactions are catalyzed, as the substrate must fit the active site for the enzyme to function.
Initially, the 'lock and key model' proposed that substrates fit perfectly into the enzyme's active site, much like a key in a lock. However, a more accurate model is the 'induced fit model.' This model suggests that the enzyme's active site slightly changes shape upon binding to the substrate, allowing for a more perfect fit, similar to how a hand fits into a rubber glove.