Enzymes Flashcards
Catalyst
speed up chemical reactions, but aren’t part of the substrate or product
Favorable Reactions
exergonic (-G), can move right, slow, need input to speed up
Non Favorable Reactions
don’t move (G=0) or endergonic (+G) (move left
Transition State
middle step for chemical reactions, needs more energy than reactants, makes stable complex molecules
Activation Energy
energy needed to get to transition state
Low Barrier (Activation Barrier)
fast reaction, most reactants have enough energy
High Barrier (Activation Barrier)
slow reaction, few reactants have enough energy
How to speed up reactions in favorable reactions:
increase temp of reactants, lower activation barrier
Enzyme
catalysts in biological systems, either protein or ribosome, lower activation energy barrier
Enzyme-Substrate Complex
where substrate and enzyme interact
Active Site
cavity structure in enzyme where substrate binds, very specific shape
Induced Fit
substrates interact to see if they can fit perfectly in the enzyme, physical change in enzyme if correct
Covalent Modification
covalently changed shape and function of enzyme
Phosphorylation
add a phosphate group to protein, changes 3D structure
Dephosphorylation
remove phosphate group from protein, changes 3D structure
Proteolytic Cleavage
inactive enzyme becomes active, removes amino acids from protein via peptidases
Saturation
max load of substrates for available enzymes, can’t keep reacting
Effector Molecules
regulate enzyme activity by binding to them
Activators
increase rate of reaction
Inhibitors
decrease rate of reaction
Irreversible Inhibitors
covalently bond to enzyme at active site permanently, used to harm other organisms
Reversible Inhibitors
non covalently bond to enzyme, falls off after time, used in body cells to regulate enzymes
Competitive Inhibitors
have same shape as substrate, bind to active site to block substrate, reversible
Noncompetitive Inhibitors
bind away from active site, changes enzyme structure, reversible
Allosteric Effectors
keeps enzyme in one shape (on/off) by binding to them, saves energy in pathways
Allosteric Activator
turns enzyme on, in functional shape (able to bind substrate)
Allosteric Inhibitor
turns enzyme off, in nonfunctional shape (can’t bind substrate)
Feedback Inhibition
buildup of enzyme products inhibits initial enzyme reaction until the product is needed again
