Biochem 8 Enzyme Catalysts

Define an enzyme as a biological catalyst

A substance that accelerates a chemical reaction without being consumed in the process

Describe how an enzyme affects the transitions state and activation energy of a reaction

Calculate rate enhancement of an enzyme-catalyzed reaction

List the different catalytic approaches enzyme may use

Turnover number definition

Maximal number of substrate molecules converted to product by one enzyme molecule per second

What do reactants need to overcome before reacting?

Activation energy

What is at the peak of a Gibbs Free Energy diagram?

A transition state

What is the induced-fit model?

It account for changes in the shape of the enzyme active site that accommodates the substrate and facilitate the reaction

What is the lock-and-key model?

The substrate is described as fitting into the active site as a key fits into a lock; specificity

What does a +ΔG mean?

Reaction is not spontaneous in the forward directionWha

What does a -ΔG mean?

Reaction is spontaneous in the forward direction; -ΔS in equation

Electrostatic catalysis

Preferential binding to transition state via noncovalent interactions

Induced fit

Distortion of substrate and active site

How does the enzyme achieve rate enhancement?

Binding substrates to optimize proximity and orientation

Covalent catalysis

Altering reaction pathway to include intermediate states

Acid/base catalysis

Key residues at the active site that can act as acid or base for proton transfer

Metal ion catalysis

Metal ions at the active site that can accept electron density or help promote formation or certain ions