Question

a biochemist generates an enzyme activity curve for an unknown enzyme. the curve is shown below. which statement best explains the shape of this curve? the enzyme has a single active site. substrate binding at this particular site occurs within a narrow ph range, termed the equivalence point. the enzyme has a single active site. as the enzyme binds substrate, the activity of the enzyme stalls until it can clear the active site. the enzyme has multiple active sites. as the enzyme binds substrate at one site, its affinity for binding substrate at other active sites increases. the enzyme has multiple active sites. as the substrate concentration increases, all sites must be equally bound for the reaction to proceed. the enzyme has multiple active sites. substrate binding at each of the sites is dependent upon the temperature of the reaction.

Explanation:

The sigmoidal - shaped enzyme - activity curve is characteristic of allosteric enzymes which have multiple active sites. When an allosteric enzyme binds a substrate at one active site, it causes a conformational change that increases the affinity of the other active sites for the substrate, leading to a cooperative binding effect.

Answer:

The enzyme has multiple active sites. As the enzyme binds substrate at one site, its affinity for binding substrate at other active sites increases.