02b: Enzyme Catalysis Flashcards
Enzymes can accelerate reactions by factor of:
10^6 or more
Are cofactors proteins?
No
Enzyme with cofactor is (active/inactive) and called:
Active
Holoenzyme
Enzyme without cofactor is (active/inactive) and called:
Inactive
Apoenzyme
Inorganic cofactors are:
Metal ions
Organic cofactors are:
Coenzymes
(X) are derived from vitamins and facilitate enzymatic activity.
X = coenzymes
Co-substrate is a type of (X) that’s (loosely/tightly) bound to enzyme.
X = coenzyme
Loosely
Prosthetic group is a type of (X) that’s (loosely/tightly) bound to enzyme.
X = coenzyme
Tightly/covalently
(X) are coenzymes changed by the reaction.
X = co-substrates
T/F: an enzyme can only catalyze one specific reaction.
False - can also catalyze other closely related reactions
T/F: enzymes differ in degree of substrate specificity.
True
Free energy change for reaction depends on:
Only free E of products (minus) free E of reactants
What can change in free E tell us about the reaction rate?
Nothing
What can change in free E tell us about the reaction’s spontaneity?
If reaction is endergonic, exergonic, or at equilibrium
What are P, [X], pH, and T at standard conditions?
P = 1 atm [X] = 1 M pH = 7
No real standard for T
What’s the basis for reaction coupling (in terms of free energy change)?
In non-equilibrium conditions, (delta)G sign can differ from (delta)Go sign.
How do enzymes alter free energy change?
They don’t! Can’t alter thermodynamic laws (free energy or equilibrium)
Transition state has (high/low) stability and (high/low) free energy.
Low; high
T/F: Enzymes enhance both forward and reverse reaction rates.
True
Transition state theory assumes equilibrium between:
Substrate and transition state
Enzyme active site is most responsible for:
Lowering activation energy (by promoting formation of transition state)
T/F: active site makes up large portion of enzyme volume.
False
Formation of (reversible/irreversible), non covalent interactions, such as (X), in active site cause:
Reversible
X = H bonds, van der waals
Cause release of free (binding) E