WHAT ARE ENZYMES? Enzymes are a _________________________________ –Which means they are made up of __________________ __________________________________________________ –Catalysts: molecules that are used to speed up a chemical reaction without actually taking part in the reaction; the enzyme remains unchanged Enzymes are assembled by our cells __________________________________________________

- CATABOLISM - ANABOLISM How do enzymes work? - Substrate: - Active site: - Enzyme-substrate complex:

Catalytic Cycle of an Enzyme reaction What reaction is being shown? What are the 2 clues?

All enzymes have an optimal temp. and an optimal pH Above the optimal temp. enzymes will be inactivated - Increased heat breaks the bonds holding the protein in a folded shape - “unfolding” the protein is called denaturing - a denatured protein doesn’t work Decreased temperature doesn’t denature enzyme. Just slows molecules down so they move too slowly to successfully react. Changes in the concentration of H+ (pH) will also cause enzymes to denature.

DENATURATION

Enzyme Function Graphs OPTIMUM TEMP OF THIS ENZYME? Would it make a good Human enzyme? Where might these enzymes work based on their optimal pH?

How fast an enzyme can increase the rate of a reaction depends on: 1.____________________________________________________ 2.____________________________________________________

Saturation Curve: What does it tell us? Why does this happen?

By making it easier for substrates to react, enzymes lower the Activation energy of the chemical reaction Activation energy: _________________________________________ __________________________________________________________ - think of it as the “cost” of the reaction; the enzyme is a “coupon” Progression of the reaction

What it REALLY looks like

Enzymes are EXTREMELY specific__________________________________________________________ Each enzyme’s active site will ONLY fit one specific substrate There are two theories on how this works: 1.Lock and Key Theory: ______________________________________________ ________________________________________________________________ 2.Induced fit Theory: ______________________________________________ ________________________________________________________________ Research data suggests Induced fit is more accurate

Some enzymes need helper molecules: Coenzymes: __________________________ (example: vitamins) Cofactors: ___________________________ (Examples: Zn, Cu) _________________________________________ _________________________________________ _________________________________________

Inhibiting an enzyme _________________________________________________ Can be caused by outside molecule – drugs/poisons Can be caused by inside molecule if your body wants to temporarily shut down a reaction –Why waste the energy, if you don’t need the product! Competitive InhibitionCompetitive Inhibition– molecules that are similar in shape to the substrate bind to the active site and block the substrate; No chemical reaction can happen Non-competitive InhibitionNon-competitive Inhibition– molecule binds to a part of the enzyme and alters the shape of the active site; No chemical reaction occurs Two ways to inhibit an enzyme Both are reversible if you get rid of inhibitor

Inhibitor sits in active site Substrate can’t fit No reaction Inhibitor changes active site Substrate can’t fit No reaction