Lesson 5 Enzymes

Catalyst: something that increases the rate of reactions Enzymes are biological catalysts Often ends with –ase Most enzymes are proteins One enzyme works only with one specific reaction Shape of enzyme is very important Enzymes are not used up when the reaction happens

Enzyme structure Enzymes have grooves or pockets called active site Reactants (called substrate) bind to the active site, where the reaction happens The resulting molecules are called products

Enzyme structure Enzymes may be inhibited or activated by other chemicals that bind to it Inhibitor: prevents it from working Activator: allows it to work

Activation Some enzymes require an activator to bind to it before substrates can

Inhibition Noncompetitive inhibition: Inhibitor attaches to enzyme but not in the active site

Inhibition Competitive inhibition Inhibitor binds to active site so substrate cannot bind

Inhibition Many reactions in the body occur in a sequence Feedback inhibition: The product of one reaction inhibits an enzyme of a previous reaction

Enzyme activity Since most enzymes are proteins, they only work when they are in the right shape Proteins will denature (change shape) if they are under the wrong conditions Ex. Different pH, temperature