- Biological catalysts à speed up chemical reactions in the body without being consumed in the process
- Reduce the activation energy needed for reactants to reach the transition state
Don't change the ΔG
o Heat can provide activation energy à denatures enzymes though =(
- Substrate à the specific reactant that the enzyme acts on
- Enzymes have a complex 3-D shape à means they are VERY specific on their substrate
- Names of enzymes end in -ase
- E.g. amylase catalyzes amylose into maltose
- Active Sites
- The site where the substrate binds
- Small portion of the enzyme
Pocket/groove in the 3-D shape of the enzyme
o As the substrate enters the active site
The functional groups in active site will react and cause the enzyme to change shape to accommodate the substrate
Known as the induced-fit model
- Enzyme-substrate complex à enzyme with a substrate attached
- Enzymes
- Bend, stretch, change pH etc. to break or build bonds
- Heat from the cell + enzyme activity = transition state
- Enzyme activity
- Increased with heat (too much denatures them though)
- pH à can denature them (stomach enzymes work at pH of 2
- some need cofactors
non-protein components (e.g. Zn2+ or Mn2+) that bind to active site or to substrate
o coenzymes
organic non-protein cofactors (e.g. NAD+)
Compete for active site
Reverse affect by increasing conc. of substrate
o Non competitive
Attach to non-active-site site
change shape of enzyme so the substrate doesn't fit or catalyzing action is reduced
- Control of enzymes (either through reducing production of enzyme or through inhibition)
- Allosteric sites à receptor sites a distance away from the active site
o Activator
Stabilizes the active form of the enzyme
o Allosteric Inhibitor
Stabilizes the inactive form of the enzyme
- Feedback inhibition
- A product formed later in a series of chemical reactions allosterically inhibits an enzyme working earlier on in the process
Enzyme is inhibited à Less products formed à less inhibitors à enzyme activity goes up à more products (inhibitors) formed
o E.g. threonine is catalyzed into isoleucine
Isoleucine inhibits the first enzyme that would act on threonine
- Milk à cheese
- Creating wine
- Brewing beer
- Starch à ethanol
- Removing stains