Enzymes Flashcards
What is one of the fastest enzymes?
Carbon anhydrase
Enzymes are _____ specific
highly
Does an enzyme determine if a rxn occurs or not?
No, free energy does
For a spont. rxn. to occur G must be
Negative
At equilibrium G is
0
What is free energy independent of?
Path of formation
Does G tell us about the rate of the reaction?
No
What are the 2 standard cond. for standard free energy change
reactants and products have concentrations of 1M, 1atm for gas
Temperature is 298K
What is the formula for delta G?
deltaG=standardG + RTln[products]/[reactants]
What is G at equilibrium?
0
what is the G formula at equilibrium?
StandardG’=-RTlnKeq
G must be _____ to be energetically favourable (spont)
Negative
Are spontaneous rxns instantaneous?
Enzymes
Enzymes makes spont rxns that are ______ favourable
kinetically
What is the symbol for activation energy?
=|
Enzymes decrease the ____ to overcome the
activation energy, activation energy barrier
What are the x and y axis of a typical enzyme lookin graph?
X=rxn progress
Y=free energy
How do enzymes lower the Ea
Stabilize the transition state
What is the symbol for transition state?
X=|
Do enzymes alter the rxn rate? The equilibrium?
Yes, no
Where do the residues of the active site come from?
Different positions in amino aa seq
an active site forms ______ with substrates
multiple weak interactions
specificity of substrate binding depends on
present arrangement of active site residues
What are the 5 features of the enzyme active site?
- Residues forming the active site come from different positions in aa seq
- small vol of total protein
- Unique microenvironment
- forms multiple weak interactions with substrates
- specificity depends on present arrangement of active site residue
Cofactors
non-protein compounds that bind to proteins to provide biological activity
Apoenzyme
wihtout cofactor
Holoenzyme
with cofactor
Prosthetic group
non-protein molecule tightly bound to enzyme
Cosubstrate
non-protein molecule that can dissociate from enzyme
What are coenzymes derived from?
vitamins
How is free energy released?
When many weak interactions occur b/w the enzyme and transition state
When does max binding energy occur?
during the transition state
Why do we use Gibbs free energy?
Understand whther a rxn is spont and to understand energetics
What does the active site do
stabilizes the transition state
Binding energy provides..
most of the energy used to lower the activation energy
