CHAPTER 6 Flashcards
REVIEW
BIOLOGICAL CATALYST
ENZYME
INCREASE RATE OF RXN 10^20
ENZYME
CATALYZE ONLY ONE STEREOISOMER OTHERS FAMILY OF REACTIONS
ENZYME
ALL ENZYMES ARE PROTEINS
ALL ENZYMES ARE PROTEINS
Rate of Rxn depends on
Activation Energy DG
Provides an alternative pathway with a lower activation Energy
Enzyme
The free Energy of Activation are the
Free Energy of Change
Arrow under the parabola
Arrow under the Free Energy of Activation
Free Energy of Activation Catalyzed reaction is
Free Energy of Activation Uncatalzyed rxn is
Much Less/ Less than the
Greater
Most Important Function of Proteins is
Performed by the
Catalysis
Protein, Enzyme
Enzyme Activity Decreases because of
Thermal Denaturation
Two models for Binding of Substrate to an Enzyme:
Lock and Key Model
Induced Fit Model
Complementary Shape of the Substrate and The Binding Site/ Portion of the Enzyme
Lock and Key Model
Induces Changed after the Substrate Binds to the Active Site Resulting in Complementary change of the active site and the substrate
Induced Fit Model
What Occurs After Enzyme Transition Complex is Formed
Catalysis Occurs
In the complex, S is bound to the enzyme with correct orientation with respect to the atoms it is to react with
Both Proximity and Orientation _______
Substrate + Enzyme Forms —–>
Speed Up the Reaction
Product + Enzyme —–> Product is released into
Enzyme + Product
Enzyme Catalyze Reaction Example is
It: Cleaves
Catalyzes Hydrolysis of
Chymotrypsin
Lys, His, Gln
Peptide bonds
Hydrolysis of P-nITROPHENYL Ester by Chymotrypsin
Rate is _________ on Substrate
At _____ (S) rxn rate increase with _____ on (S)
At _____ (S) rxn rate changes very_____ and a _____ rate is reached
Graph is __________
Dependent
low, increase
Very Little
max
Hyperbolic
ATCase- an _________
Similar to kinetic behavior of_______
Allosteric Proteins- Proteins in which subtle changes at one site affect the ________ and ________ at another site
_____________ and myoglobin are ____________
Allosteric Protein
Hemoglobin
Structure and Function
Chymotrypsin, Non allosteric Proteins
ATcase-
_________ the reaction
Carbamoyl Phosphate +_________ —-> Carbamoyl Aspartate +
Leads to formation of CTP and UTP needed for biosynthesis of _____ and ______
Rxn rate depends on (S) which is _______
Graph is ________
Aspartate Transcarbamoylase
catalyzes
Aspartate
HPO42-
RNA AND DNA
Aspartate
Sigmoidal
Michaelis-Menten Approach to Enzyme Kinetics
Full names: (1913, __________ and __________)
Basic Model for __________
Enzymatic Conversion the S——>___
Mechanism of Enzymatic Reaction:
Leonor Michaelis and Maud Menten
Nonallosteric Enzymes
P
E+S k-1<——>k1 ES —–>k2 E+P
Solve for Concentration of Complex (ES)
Michaelis Menten Constant: Km
ES COMPLEX CONCENTRATION
(E) = (E)t -(ES) (E)t= Total (E)
(E)t-(ES)(S)/(ES) = Km
(E)t(S)/km+(S)
If S Completely Saturates E (ES) = (E)t
If S saturates E
(ES) = (E)t
k2(E)t(S)/Km+(S)
Michaelis Menten Equation:
When (S)=Km
When the Rxn rate is half of its max value,
the (S) conc. is
Km is only appropriate for Enzymes that Exhibit
V= Vmax(S)/Km+(S)
Vmax/2
Equal to Km
Hyperbolic Curve V vs (S)
Linearizing Michaelis Menten Equation:
Equation For Hyperbola:
Equation For a Straight Line:
V=Vmax(S)/Km+(S)
1/V=Vmax(S)/Km+(S)= Km/Vmax+(S) +(S)/Vmax+(S)
1/V = Km/Vmax(S) + 1/Vmax
Line Weaver Burk Double Reciprocal Plot:
Gives Straight Line: Y and X
Gives Slope: M
Gives Intercept: B
1/V = Km/Vmax(S) x 1/(S) + 1/Vmax
1/V vs 1/(S)
Km/Vmax(S)
1/Vmax
Enzyme Inhibition:
An _________ ,Is a substance that interferes with the _____ of and enzyme and ____ the rate of reaction
An _______ is a substance that decreases the rate of an ___________ reaction
Inhibitor, Action, Slows
Inhibitor, enzyme-catalyzed
Reversible Inhibitor:
A substance that ______ to an Enzyme it can inhibit but it can be ______
Binds, Released
Competitive Inhibitor:
Binds to the _____ site and ______ access to it by substrate
Compete with the _______ for binding to the enzyme’s ________ site
Non-Competitive Inhibitor:
_______ to a site other than the _____ site and inhibits enzyme by _______ its conformation
Cannot be overcome by _________ substrate concentration
Mixed Competitive: The binding of Inhibitor affects the binding of S, and Vice Versa
Uncompetitive Inhibitors: Binds only to ES Complex preventing the Complex from releasing Products
Active, Blocks
Substrate, Active
Binds, Active, Changing
Increasing
Irreversible Inhibitor:
A substance causes ________ that cannot be _________.
Usually Involves the formation or breaking of covalent bonds to or on enzyme
Inhibition, Reversed
Competitive Inhibition:
EI <—-> +I E <—–> +S ES <—–> E+P
I = (I)/KI
I/V=Km/Vmax (I+(I)/KI) x 1/(S) + 1/Vmax
Km ________ because High S outcompetes I both vying at the same site, Vmax does not change.
Increases
Competitive Inhibitor Non-Comp
Site Binding:
Change of
Structure of E:
Effect on Km:
Effect on Vmax:
Active Site At a Site other than the Active Site
No Yes
Change No Change
No Change Change
Non-Competitive Inhibition:
1/V= Km/Vmax (I + (I)/KI) x 1/(S) +1/Vmax (I + (I)/Ki)
Vmax _______ while Km remains _______
S does not overcome Noncomp I as they are not _______ for the same site
Decreases
Constant
Competing
Enzyme Commission Classification and Nomenclature
- __ MAJOR CLASSES
Class. Sub Class, Sub-subclass, Specific Enzyme
1. Oxi
2. Trans
3.Hydro
4.Ly
5.Isome
6.Liga
6
Oxidoreductases
Transferases
Hydrolases
Lyases
Isomerases
Ligases
Catalyze oxidation-reduction reactions, electrons are –__________ from _____ molecule to another
Example: Alcohol ______ EC (1.1.1.1)
Oxidoreductases
Transferred, one
Alcohol Dehydrogenase
Transfer ___________ from one molecule to another
Example: Hex_____ EC (2.__.__.1)
Transferases
Functional Groups
Hexokinase (2.7.1.1)
Catalyze the ______ of Various bonds, Breaking molecules down using _______
Example: Lip_____ EC (__.__.1.__)
Hydrolases
Hydrolysis, Water
Lipase (3.1.1.3)
Catalyze the ________ or ________ of groups to form double bonds or break double bonds without _______ or oxidation
Example: ________ Decarboxylase EC (__.1.1.1)
Lyases
Addition or Removal, Hydrolysis
Pyruvate Decarboxylase (4.1.1.1)
Catalyze the ________ of atoms within a molecule, facilitating _______ changes.
Example: Phospho____ Isomerase EC (__.__.__.9)
Isomerases
Rearrangement, structural
Phosphoglucose Isomerase (5.3.1.9)
Catalyze the formation of ___ molecules, with the formation of new _____________ usually accompanied by hydrolysis of _____
Example: DNA ______ EC ( __.5.__.1)
Ligases
Two, chemical bonds, ATP
DNA Ligase (6.5.1.1
