Enzyme Kinetics and Inhibition Lecture

Vocabulary flashcards covering enzyme activity factors, limiting factors, maximum reaction velocity, competitive and noncompetitive inhibition, and metabolic feedback control.

Optimum pH

The pH level—such as $\text{pH } 8$—where an enzyme functions at its highest rate; shifting away from this value decreases the rate of reaction due to the formation of new hydrogen bonds.

Limiting factor (with fixed substrate concentration)

The factor that restricts the rate of reaction; initially it is the enzyme concentration and number of available active sites, but once all substrate has reacted, substrate availability becomes the limiting factor.

$$V_{max}$$

The maximum rate of reaction achieved when all enzyme active sites are occupied by substrate molecules under a fixed enzyme concentration.

Optimum temperature

The temperature at which enzyme activity peaks, noted in the lecture as approximately $37\text{ degrees}$.

Competitive inhibition

A mechanism in which an inhibitor with a shape similar to part of the substrate binds to the enzyme's active site, preventing the formation of enzyme-substrate complexes and slowing the rate of reaction without reducing the final amount of product.

Noncompetitive inhibition

A mechanism in which an inhibitor binds to an enzyme away from the active site, altering its bonds and three-dimensional structure so the active site cannot bind substrate, which lowers the reaction rate and reduces total product yield.

Allosteric site

A binding site on an enzyme located away from the active site where a noncompetitive inhibitor attaches.

End product inhibition

A feedback process in a metabolic pathway where the final product serves as an inhibitor for the enzyme that initiated the chain reaction, temporarily shutting down production when sufficient product exists.

Enzyme-substrate complex

The intermediate formed when a substrate molecule binds to the complementary active site of an enzyme during a chemical reaction.