Enzymes

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

Enzymes Are specific for what they will catalyze Are Reusable End in –ase -Sucrase -Lactase -Protease

Basic Points about Enzymes Enzymes are biological catalysts that speed up the chemical reactions of the cell. Enzymes are proteins. Enzymatic reactions occur faster and at lower temperatures because enzymes lower the activation energy for that chemical reaction. Enzymes are never consumed or used up during the reaction. They can do their job over and over again

                                                                   Enzymes are highly specific for just one substrate.  The enzyme has an active site with a unique 3-D shape into which this substrate must fit.   Enzymes catalyze both the forward and the reverse of the same reaction. Enzymes can be denatured by temperatures and pH levels outside the optimal range for that particular enzyme

How do enzymes Work? Enzymes work by weakening bonds which lowers activation energy

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 The part of an enzyme that binds to the substrate is the active site Active Site Enzyme Substrate

Extreme Temperatures Enzymes have an optimum temperature This means they do the best at a specific temperature At too hot or too cold and an enzyme may denature (unfold)

pH Different enzymes work better at different pH If the environment becomes to acidic or too basic the enzyme may denature

Substrate Concentration Enzyme needs enough substrate to do its job Too little substrate causes the enzyme to be ineffective Too much substrate no longer affects the reaction rate

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

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

Enzyme Inhibitors Cyanide inhibits an enzyme with the production of ATP. (death) Penicillin inhibits an enzyme in bacteria that helps cell walls. Aspirin inhibits enzymes used to induce pain.