1. Proteins that catalyze chemical reactions
Enzymes
Proteins that catalyze chemical reactions

2. I. Protein Structure A. primary structure = chain of amino acids
B. Secondary structure = fold amino acids
1. chains of amino acids folded over
2. held together by weak hydrogen bonds
3. H-bonds break if they get too hot
C. Tertiary structure = 3-D shape formed

4. II. Role of Enzymes A. Catalyze chemical reactions
B. Speed up all reactions in a cell
C. Enzymes are specific
1. each enzyme only works for one reaction
2. each enzyme only binds to the reactants for
that one reaction
3. enzymes do NOT become part of the
product….they can be used over and over

5. III. Enzyme Vocabulary
A. Substrate(s) = the reactant(s) that an enzyme binds to
B. Active Site = the part of the enzyme that binds to the substrate
C. lock & key mechanism = substrate fits active site

6. IV. Catalyst Mechanisms
A. Enzymes speed up chem. rxns. by lowering activation energy needed to form/break bonds
B. Enzymes can position two substrates
1. aligning correctly makes it easier to bond
2. binding substrates makes it more likely that they meet
C. Enzymes can apply stress to large molecules
1. stressing bonds makes them easier to break

8. V. Enzyme Vocabulary 2.0 A. Denaturation – Δ of 3-D structure
1. due to heat breaking Hydrogen bonds
2. change in active site shape ruins enzyme

9. B. Co-enzyme – molecule that helps enzyme
1. some enzymes can not work with out them
2. often metal ions

10. C. Inhibitors – slow or stop enzyme
1. competitive inhibitors – block active site
2. allosteric inhibitors – bind to other parts of enzyme and cause it to change shape

11. VI. Rate of reaction A. Concentration of enzyme concentration rate
B. Temperature
Temp rate unless ……
too hot, then denaturation …
C. pH too high or too low rate
D. ion concentration too high or too low rate

12. VII. homeostasis
A. keep things constantly the same throughout the cell or body
1. solute concentrations
2. ion concentrations
3. pH
4. Temperature
B. makes sure enzymes can work fast enough