1 | E n z y m e s
ENZYMES
Usually protein, but some are RNA. Work by lowering the activation energy of a reaction
Most enzymes are Proteins (tertiary and quaternary structures)
Act as Catalyst to accelerates a reaction
Not permanently changed in the process
Are specific for what they will catalyze
Are Reusable
End in –ase
-Sucrase
-Lactase
-Maltase
HOW DO ENZYMES WORK?
- Enzymes work by weakening bonds which lowers activation energy
ENZYME-SUBSTRATE COMPLEX
- The substance (reactant) an enzyme acts on is the substrate
ACTIVE SITE
- A restricted region of an enzyme molecule which binds to the substrate.
INDUCED FIT
- A change in the shape of an enzyme’s active site
- Induced by the substrate
- A change in the configuration of an enzyme’s active site (H+ and ionic bonds are involved).
WHAT AFFECTS ENZYME ACTIVITY?
3 FACTORS
1. Environmental Conditions
- Extreme Temperature are the most dangerous
- - high temps may denature (unfold) the enzyme.
- pH (most like 6 - 8 pH near neutral)
- Ionic concentration (salt ions)
2. Cofactors and Coenzymes
- Inorganic substances (zinc, iron) and vitamins (respectively) are sometimes need for proper
enzymatic activity.
- EX: Iron must be present in the quaternary structure - hemoglobin in order for it to pick
up oxygen.
3. Enzyme Inhibitors
- EX: Competitive inhibitors: are chemicals that resemble an enzyme’s normal substrate and compete
with it for the active site.
- EX: 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.
