Enzymes• Special proteins• Increase the speed of

biochemical reactions (catalysts)

• Lower the activation energy of chemical reactions

• Usually end in “ase”• Named after the

substrate they act upon• Critical to life

How Enzymes Work

• Active site: region where the reaction takes place – specific shape

• Substrates: reactants– specific shape– bind to active site

How Enzymes Work

1. Substrates bind to enzyme’s active site. - lock and key or puzzle piece fit

How Enzymes Work

2. Enzyme substrate complex- chemical reaction occurs

Enzyme-Substrate

Complex

How Enzymes Work

3. New products are released- enzyme can be used again

Types of Reactions

• Decomposition: when a large molecule is broken down into smaller molecules– Ex: 2H2O2 2H2O + O2

• Enzyme = catalase

• Synthesis: when 2 or more small molecules are combined to form a larger molecule– Ex: RNA Polymerase combines nucleotides to form

RNA

How Enzymes Work

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

Conditions

• Most enzymes need a certain temperature and pH range• If enzymes are exposed to conditions outside their designated

temperature and pH range, they could denature (unfold and become non-functional)

http://www.youtube.com/watch?v=SUCgAxI8rhg

QuizSubstrates/Reactants

Active Site

Enzyme

Enzyme-Substrate Complex

Product

Quiz (cont.)Decomposition or Synthesis Reaction?

Decomposition or Synthesis Reaction?