Enzymes & Inhibition Flashcards
Allosteric effector
Binds at the allosteric site and induces a change in the conformation of the enzyme so the substrate can no longer bind to the active site. Displays cooperativity, so it does not obey MichaelisMenten kinetics.
Hill coefficient = 1
No cooperativity (normal MM kinetics); Substrate binding doesn’t affect affinity
this enzyme Moves a functional group from one molecule to another
transferase
competitive inhibition
Hill coefficient
measure of cooperatively (ie Hb, where you see sigmoidal kinetic curves that don’t follow Michaelis-Menten)
hydrolysis of fats is included in this class of enzymes
lyases
in uncompetitive inhibition, Vmax…
decreases
catalyzes cleavage without H2O or the transfer of electrons
lyases
On the LWBP, competitive inhibition effects the X-intercept by…
increases it (moves toward the origin)
Prosthetic groups
tightly bound cofactors or coenzymes that are necessary for enzyme function
Hill coefficient > 1
positive cooperativity; Substrate binding increases affinity
dehydrogenase, oxidase, and peroxidase are all ____ enzymes
oxidoreductases
this type of enzyme is known for addition/synthesis reactions and usually requires ATP
ligases
Glycosylation
covalent modification w/ carbohydrate (adding sugar)
phosphotransferases that add a phosphate group, usually with ATP as a donor
kinases
On the LWBP, competitive inhibition effects the Y-intercept by…
no change
Enzyme-catalyzed reactions w/ high enzyme-substrate affinity will reach the ½Vmax benchmark at a (lower/higher) [substrate] aka have a (lower/higher) Km; lower enzyme-substrate affinities → needing a (lower/higher) [substrate] to reach ½Vmax (have a (lower/higher) Km).
Enzyme-catalyzed reactions w/ high enzyme-substrate affinity will reach the ½Vmax benchmark at a lower [substrate] aka have a lower Km; lower enzyme-substrate affinities → needing a higher [substrate] to reach ½Vmax (have a higher Km).
in noncompetitive inhibition, Km…
doesn’t change
these enzymes introduce a phosphate group into an organic molecule (glucose)
phosphorylase
this type of enzyme joins two large biomolecules, often of the same type
ligases
cofactor
Inorganic ions and metal cation; like Fe²⁺ and Mg²⁺; directly involved in the enzyme’s catalytic mechanism
If Vmax increases, the paramater values ______. The intercept _____ and moves ______ the origin.
If Vmax increases, the paramater values doubles. The intercept decreases (becomes less +) and moves towards the origin.
this type of enzyme is used to create bonds b/t Okazaki fragments
ligases
In this type of inhibition, the inhibitor is similar to the substrate and binds @ the active site
competitive inhibitor
In enzyme kinetics, calculate v0
this class of enzymes includes the interconversion of isomers, constitutional & stereoisomers
isomerases
in this type of inhibition, the inhibitor binds w/ unequal affinity to the enzyme and the enzyme-substrate complex
mixed inhibition
a synthase could also be a ______ but a synthetase must be a _____
a synthase could also be a synthase but a synthetase must be a ligase
Coenzyme
Organic molecule; like heme, NAD⁺ & Coenzyme A. Many are derived from vitamins
heterotrophic effector
where is the binding site in noncompetitive inhibition
In this type of inhibition, the inhibitor binds with equal affinity to the enzyme and the enzyme-substrate complex
noncompetitive inhibition
Irreversible inhibition:
alters the enzyme so that the active site is unavailable for a prolonged duration or permanently; new enzymes molecules must be synthesized for the rxn to occur again
On the LWBP, uncompetitive inhibition effects the X-intercept by…
decreases it (moves away from the origin)
If the mixed inhibitor ends up binding more readily to the _____ Km is lower
If the mixed inhibitor ends up binding more readily to the enzyme-substrate complex Km is lower
Enzyme kinetics equaiton, what does v = ?
On the LWBP, uncompetitive inhibition effects the Y-intercept by…
increases (moves away from the origin)
where is the binding site in competitive inhibition?
active site
these remove a phosphate group
phosphatase
in mixed inhibition, Km…
increases or decreases
in competitive inhibition, Km…
increases
Km
The [S] at which an enzyme runs at half its Vmax.
transaminase is an example of a ______ enzyme
transferase
nucleic acid synthesis uses these kind of enzymes
ligases
On the LWBP, mixed inhibition effects the X-intercept by…
increases or decreases it (moces towards or away from the origin)
how does increasing the amount of substrate affect Vmax
increasing substrate = increases Vmax
On the LWBP, mixed inhibition effects the Y-intercept by…
increases (moves away from the origin)
isomerases include
oxidoreductases, transferases, lyases
Hill coefficient n < 1
negative cooperativity; Substrate binding decreases affinity for subsequent substrate
these generates either a double bound or ring structure
lyases
Cleavage with H₂O = ____ enzyme
hydrolases
Noncompetitive inhibition
aminotransferase is an example of a _____ enzyme
transferase
On the LWBP, noncompetitive inhibition effects the X-intercept by…
no change
In this type of inhibition, the the inhibitor binds only with the enzyme-substrate complex
uncompetitive inhibition
On the LWBP, noncompetitive inhibition effects the Y-intercept by…
increases (moves away from the origin)
If the mixed inhibitor ends up binding more readily to the _____ Km is higher
If the mixed inhibitor ends up binding more readily to the enzyme Km is higher
in mixed inhibition, Vmax…
decreases
where is the binding site in mixed inhibition
allosteric site
These only require 1 substrate when cleaving but 2 for the reverse
lyases
Vmax
The max rate (enzyme velocity) at which an enzyme can catalyze a reaction; when all enzyme active sites are saturated with substrate
in uncompetitive inhibition, Km…
decreases
in competitive inhibition, Vmax…
doesn’t change
If Km increases, the paramater values ______. The intercept _____ and moves ______ the origin.
If Km increases, the paramater values doubles. The intercept increases (becomes less negative) and moves towards the origin.
Suicide inhibitor:
A substrate analogue that binds irreversibly to the active site via a covalent bond.
homotrophic effector
An allosteric regulator that is also the substrate.
uncompetitive inhibition
in noncompetitive inhibition, Vmax…
decreases
phosphatase, peptidase, nuclease, lipase = all are ____ enzymes
hydrolases
methyltransferase is an example of a _____ enzyme
transferase
where is the binding site in uncompetitive inhibition
enzyme-substrate complex
