Enzymes Mr. Spoor Biology 1

What Are Enzymes? Most enzymes are Proteins Act as Catalyst to accelerates a reaction Not permanently changed in the process

Enzymes Are specific for what they will catalyze Are Reusable End in –ase -Amylase -Lactase -Sucrase -Maltase -Pepsin (for proteins)

How do enzymes Work? Enzymes work by weakening bonds which lowers activation energy, and speeds up reactions.

Enzymes Without Enzyme With Enzyme Free Energy Progress of the reaction Reactants Products Free energy of activation

Enzyme-Substrate Complex The substance (reactant) an enzyme acts on is the substrate Enzyme Joins Substrate

Active Site A restricted region of an enzyme molecule which binds to the substrate. Active Site Enzyme Substrate

Lock and Key Hypothesis Enzymes and substrates fit together like a lock and key. -The substrate is like the key, and has an exact shape match for the enzyme, which is like a lock. -one enzyme, one substrate.

Induced Fit A change in the shape of an enzyme’s active site Induced by the substrate

Induced Fit A change in the configuration of an enzyme’s active site (H+ and ionic bonds are involved). Induced by the substrate. Enzyme Active Site substrate induced fit

What Affects Enzyme Activity? Four factors: 1. Temperature 2. pH 3. Substrate Concentration 4. Inhibitors

What Affects Enzyme Activity? 1. Extreme Temperature are the most dangerous - high temps may denature (unfold) the enzyme. 2. pH (most like 6 - 8 pH near neutral) 3. Substrate concentration (The more you have, the faster it reacts, to a point where all enzymes are “full”)

What is the optimal pH for gastric protease to function? ….intestinal protease? Within which pH range will both enzymes function?

Two examples of Enzyme Inhibitors a. Competitive inhibitors: are chemicals that resemble an enzyme’s normal substrate and compete with it for the active site. Enzyme Substrate Competitive inhibitor

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. Enzyme Noncompetitive Inhibitor Substrate active site altered