Final answer:
The statement is true; the active site of an enzyme comprises only about 10% to 20% of its surface and is structured to specifically bind a particular substrate, utilizing amino acid residues with unique side chains to catalyze reactions.
Step-by-step explanation:
The statement that the active site of an enzyme usually occupies only a small fraction of the enzyme surface is true. Enzyme action is highly specific because the active site is uniquely structured to bind with its particular substrate, much like a lock and key. In most cases, the active site forms only about 10% to 20% of the enzyme's overall surface. This specificity is due to the precise arrangement of amino acids that create a three-dimensional shape conducive to the enzyme's particular function. The interaction between an enzyme and its substrate occurs at the active site, leading to a biochemical reaction. Amino acid residues within the active site, often with distinctive side chains such as His, Cys, Asp, Arg, and Glu, facilitate the catalytic process.
While certain enzymes follow the lock-and-key model, others operate through an induced fit mechanism, where the active site undergoes minor adjustments to accommodate the substrate. This flexibility allows enzymes to function with a small group of similar substrates. The dynamic nature of enzyme structures and their interaction with substrates is essential for enzyme specificity and catalytic efficiency. Following the reaction, the products are released from the active site, and the enzyme remains unchanged, ready to catalyze another reaction.