Ch. 13 Enzymes

Enzymes

Proteins that speed up chemical reactions

Substrates

The reactants in an enzyme catalyzed reaction

What is the impact of enzymes on biochemical processes?

They accelerate biochemical processes and lower the energy of activation

Catalyzed rate vs uncatalyzed rate vs ratio

Catalyzed rate- 3 × 10^4/sec

Uncatalyzed rate- 3 × 10^-10/sec

Ratio- 1 × 10^14

6 nomenclature of metabolic reactions

1. Oxidoreductases- enzymes that catalyze oxidation-reduction reactions

2. Transferases- the transfer of functional groups

3. Hydrolases- enzyme that catalyze reactions in water

4. Lyases- bond cleavage by means other than hydrolysis or oxidation

5. Isomerases- changes in the same molecule

6. Ligases- formation of bonds with ATP cleavage

Coenzymes vs cofactors

Coenzymes- vitamins

Cofactors- inorganic metals

The reaction rate is proportional to …

The concentration of reactant molecules with the transition state energy

Free energy

Energy barrier

DeltaG++ (Increases the reaction rate when it decreases)

Zero order kinetics vs first order reaction

Zero order kinetics- enzyme reaches this at higher concentrations of substrate

First order reactions- the rate is proportional to at low concentrations of substrate

What happens when [S] is high and when [S] is low

Low [S]- the rate equation is 1st order with respect to [S]

High [S]- the rate equation zero order with respect to [S]

Competitive, non competitive , and uncompetitive Vmax

Competitive- compet to bind to active site

Non competitive- binds to another site

Uncompetitive- wipes out enzym

Ribozymes vs Abzymes

Ribozymes- RNA molecules that display enzyme activity in the absence of protein

Abzymes- antibodies raised to bind the transition state of a reaction of interest