Chapter 6 Flashcards
Oxidoreductases
oxidation-reduction reactions
Transferases
transfer functional groups from one molecule to another
Hydrolases
hydrolysis reactions - using water to break one molecule into two
Lyases
remove a group from one molecule and rearrange the electrons
Isomerases
convert two molecules with the same formula into different structures
Ligases
join two molecules together
What is the catalytic cycle of an enzyme?
- substrate binding
- substrate activation
- catalytic event
- product release
Name the 6 classes for enzyme nomenclature
oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases
How does a catalyst increase the rate of a reaction?
by lowering the activation energy requirement
Activation Energy
how much energy required to get to a state to turn substrate into product
Active Site
where substrate binds to enzyme
Prostetic groups
small organic groups or metal ions on an enzyme that function as electron acceptors
Lock and Key Model
early model that explained enzyme specificity but not catalytic event
Induced Fit Model
when enzyme binds to substrate, both change shape
What is initial binding of substrate and enzyme caused by
RANDOM COLLISION!
Km
michaelis constant
specific substrate concentration at which the reaction proceeds at half it’s max speed
Vmax
upper limit of reaction rate
only way to speed up is to get more enzymes
Enzyme Regulation
mechanisms that adjust the rate of enzyme catalyzed reactions
5 types of enzyme regulation
alter temp or pH, allosteric regulation, covalent modification, competitive inhibition, and substrate level regulation
Competitive Inhibition
molecule binds to the active site so that substrates can’t bind
what are substrate analogs
pretend substrates used in competitive inhibition
Allosteric Regulation
binding of regulatory molecules at allosteric site that can turn molecule on or off
Feedback Inhibition
when cell has made enough of the product, the product binds to the allosteric site and inhibits the enzyme that made it
Covalent Modification
enzyme activity affected by addition or removal of chemical groups via covalent bonding
Types of covalent modification
proteolytic cleavage and phosphorylation/dephosphorylation
proteolytic cleavage
one-time irreversible removal of a portion of the polypeptide chain
Ribozymes
RNA molecules that act as catalysts
