Enzyme Flashcards
(16 cards)
catalyst
substance that lowers the amount of energy required for a chemical reaction to occur without being consumed in the process
Catalysts can only speed up reactions that would normally take place anyway.**.
Enzymes
biological protein catalysts
when do chemical reactions take place
when molecules collide with enough force and with the correct orientation for bond breaking to occur.
energy required to begin a reaction:
activation energy (Ea)
How do enzymes decrease the Ea
stretching and bending chemical bonds (weaken)
or
providing an acidic environment (lowering the pH)
Enzyme Examples
Lipase →Speeds up the hydrolysis of triglycerides.
Protease →Catalyzes the breakdown of proteins into peptides and amino acids.
Amylase → Catalyzes the hydrolysis of starch to sugars.
Enzyme Composition
proteins, which composed of long chains of amino acids connected via peptide bonds.
many enzymes are composed of two or more polypeptides and therefore exhibit quaternary structure
NEARLY all are globular proteins (exception = myosin, an ATPase)
substrate
Reactant that an enzyme acts on.
The substrate binds to a particular site on the enzyme to which it is attracted.
Enzymes are very specific for the substrate to which they bind.
What is the induced fit model
interactions between functional groups cause the enzyme to change shape, thereby better accommodating the substrate.
what do many enzymes require
cofactors → non-protein (like a metal) that binds to an enzyme. The enzyme will NOT work with without it!
Examples: Fe, Cu, Zn, Mn, Mg
Cofactors that are organic (not metals) are called coenzymes.
They are usually derived from water soluble vitamins.
Enzyme inhibitors
slows it down
They do this by:
Binding to the active site of the enzyme (competitive inhibition);
Or
Binding to other critical sites located elsewhere on the enzyme (non-competitive inhibition).
Allosteric molecules
bind to a site other than the active site
Allosteric activators
hold the enzyme in its optimum state.
Allosteric inhibitors
hold the enzyme in its inactive state
Feedback Inhibition
a product of one reaction (near end) allosterically inhibits an enzyme of an earlier reaction.
optimal pH and temperature
36.7°C
pH = 7.2 - 7.4
Enzyme activity decreases above and below the optimal temperature and pH.
If too high, denaturation of the enzyme occurs.
