Lecture 17 Flashcards
A chemical agent that accelerates the rate of a reaction without being changed by the reaction.
Catalyst
A non-protein group that binds to the enzyme for catalytic activity.
Cofactor
Small organic cofactors which are often
derived from vitamins.
Coenzyme
Metal Ions - iron, magnesium, manganese,
cobalt, copper, zinc, and molybdenum.
Common Cofactors
NAD+/NADH, FAD+/FADH, vitamins
Common Coenzymes
An inactive enzyme.
Apoenzyme
An active enzyme with its coenzyme or cofactor bound.
Holoenzyme
What determines the function of an enzyme?
Structure
What do substrates produce in a reaction?
Products
What are the functions of cofactors and coenzymes?
To help an enzyme become active and work better
What does an enzyme need to be active?
A cofactor or a coenzyme
What factors affect enzyme activity?
1) Concentration of a substrate
2) Temperature and pH levels
3) Control mechanisms
Which mechanisms regulate enzymes?
1) Competitive and Noncompetitive regulation
2) Allosteric Regulation
Non-substrate molecules that bind to an enzyme and decrease its activity
Enzyme Inhibitors
Molecules reassemble the substrate and compete for the active site (substrate is unable to bind)
Competitive Inhibition
Molecule binds at a site other than the active site, slightly changing the active site’s shape. The substrate is able to bind, but the reaction is blocked
Noncompetitive Inhibition
Any site on an enzyme besides the active site
Allosteric Site
What does allosteric regulation do?
Makes an enzyme work better or not at all
The enzyme binds strongly to its substrate through allosteric activator
High Affinity State
The enzyme binds the substrate weakly or not all through allosteric inhibitors
Low Affinity State
Excess product binds to an allosteric site which inhibits the enzyme and stops activity
Negative Feedback Inhibition
Excess product binds to an allosteric site which activates the enzyme and continues the activity
Positive Feedback Inhibition
