Enzymes and Enzyme Kinetics

This set of flashcards covers the fundamental concepts of enzymes, their classifications, mechanisms, kinetics, and inhibitions based on lecture notes from CHEM 8020.

What are enzymes?

Protein catalysts that increase the rate of chemical reactions.

What suffix do most enzymes have?

The suffix '-ase'.

What is the function of lactase?

It catalyzes the breakdown of lactose into glucose and galactose.

Name the first class of enzymes and what they do.

Oxidoreductases: Catalyze oxidation-reduction reactions.

What do transferases do?

Catalyze the transfer of C-, N-, or P-containing groups.

How do hydrolases function?

They catalyze the cleavage of bonds by addition of water.

What is the role of lyases?

Catalyze cleavage of C-C, C-S, and certain C-N bonds.

Describe the function of isomerases.

They catalyze the rearrangement of atoms within a molecule.

What do ligases do?

Catalyze the formation of bonds between carbon and O, S, and N.

What are translocases responsible for?

Moving ions or molecules across membranes.

What is the significance of an enzyme's active site?

It is the specific region where the substrate binds to catalyze a reaction.

How can enzyme activity be regulated?

Enzyme activity can be regulated through allosteric regulation, covalent modification, and expression rate regulation.

What is the difference between competitive and noncompetitive inhibition?

Competitive inhibition occurs when an inhibitor binds to the active site, while noncompetitive inhibition occurs when an inhibitor binds to an allosteric site.

What happens to Km in competitive inhibition?

Km increases because more substrate is needed to reach ½ Vmax.

Describe the Michaelis-Menten equation.

It describes the relationship between substrate concentration and reaction rate: Vo = Vmax[S] / (Km + [S]).

What does Vmax represent?

The maximum reaction velocity when the enzyme is saturated with substrate.

What is Km?

The Michaelis constant indicating the substrate concentration at which the reaction velocity is half of Vmax.

What is an allosteric enzyme?

An enzyme composed of multiple subunits that binds substrate cooperatively.

How does temperature affect enzyme kinetics?

Increasing temperature typically increases reaction velocity until the enzyme denatures.

What is feedback inhibition?

A process where the end product of a metabolic pathway inhibits an enzyme involved in its synthesis.

What factors can affect the speed of an enzyme-catalyzed reaction?

Substrate concentration, temperature, pH, enzyme concentration, and the presence of inhibitors.