What is the process called when one substrate binding increases the affinity of the enzyme for additional substrates?

The process where one substrate binding increases the affinity of the enzyme for additional substrates is known as cooperativity. This phenomenon typically occurs in enzymes that exhibit allosteric regulation, which means that the binding of a substrate to one active site can influence the activity of other active sites on the same enzyme molecule.

In cooperativity, the initial binding of a substrate changes the conformation of the enzyme, often leading to a more favorable state for additional substrates to bind. This can result in a sigmoidal (S-shaped) curve when substrate concentration is plotted against the reaction rate, reflecting the increased likelihood of substrate binding as more molecules bind.

This concept is crucial in understanding enzyme kinetics, as it illustrates how enzymes can display varying affinities for substrates depending on their occupancy levels. While terms like allosteric modulation describe a broader category that includes cooperativity, it specifically refers to the cooperative aspect of substrate binding. Other terms in the question, such as inhibition and substrate saturation, describe different mechanisms or states that do not fit this particular scenario of increased affinity due to substrate binding.