EnzymEnzymeses

Question:Question:•What are enzymes?

EnzymesEnzymesAnswer:Answer:1.Most enzymes are proteins.2.Biological Catalyst - a chemical

agent that accelerates a reaction without being permanently changed in the process.

EnzymesEnzymes3. Selective: enzymes are specific for which they

will catalyze- (Specificity- depends upon 3D)

4. Recycled: enzymes are reusable.5.”ase” endings: examples: amylaseexamples: amylase

catalasecatalase

lactaselactase

Question:Question:•How do enzymes work?

EnzymesEnzymes

Answer:Answer:

Enzymes Enzymes speed up the cell’s chemical reactions by lowering the energy of activation.

EnzymesEnzymes

Energy

Progress of the reaction

Reactants

Products

Activation energy with enzymeActivation energy with enzyme

Without Enzyme

With Enzyme

SubstrateSubstrate

• The substance (reactant) an enzyme acts on.

Enzyme

Substrate

Active SiteActive Site

• A restricted regionrestricted region of an enzymeenzyme molecule which bindsbinds to the substratesubstrate.

Enzyme

Active Site

Substrate

Induced FitInduced Fit

• A change in the configuration of an enzyme’s active site (H and ionic bonds are involved).

• Induced by the substrate.

Enzyme

Active Sitesubstrate

induced fit

Enzymatic ReactionEnzymatic Reaction

substrate (sucrose)substrate (sucrose) + enzyme (sucrase) enzyme (sucrase)

enzymeenzyme--substratesubstrate complex complex

and +sucrasesucrase

glucoseglucose fructosefructose

productsproducts + + enzymeenzyme

Enzyme Video

http://brightstorm.com/science/biology/chemical-basis-of-life/enzymes/

What Affects Enzyme What Affects Enzyme Activity?Activity?

•Two factors:Two factors:

1.Environmental 1.Environmental ConditionsConditions

2.Enzyme Inhibitors2.Enzyme Inhibitors

1. 1. Environmental Environmental ConditionsConditions

• Enzymatic reactions are very specific. The following environmental conditions affect enzymatic reactions:

1. Temperature (extremes most dangerous) high temps may denature denature the enzyme. enzyme.

2. pH (most like 6-8 pH- neutral)

2. Enzyme Inhibitors2. Enzyme Inhibitors

• Two examples:Two examples:

a. Competitive inhibitors: are chemicals that resembleresemble an enzyme’s normal substrateenzyme’s normal substrate and competecompete with it for the active siteactive site.

Enzyme

Competitive inhibitor

Substrate

2. Enzyme Inhibitors2. Enzyme Inhibitors

b. Noncompetitive inhibitors: Inhibitors that do not enter the active

site, but bind to another part of the enzyme causing the enzyme to change its shape, which in turn alters the active site.

Substrate Enzyme

active site altered

NoncompetitiveInhibitor