No, K m is unique for each enzyme-substrate pair.
Catalytic and regulatory sites.
By measuring initial velocities at various substrate concentrations with a fixed enzyme concentration.
Substrates.
Substances that bind to an enzyme at a site other than the active site, reducing its activity regardless of substrate concentration.
Enzymes that catalyze the hydrolysis of chemical bonds.
Allosteric regulation and Covalent modification.
Phosphoenolpyruvate (feedback inhibition).
Isomerases catalyze the rearrangement of molecular structures.
Enzymes that transfer functional groups from one molecule to another.
It raises Km without affecting Vmax.
ADP.
For the substrates and type of reaction with the suffix '-ase'.
Velocity is usually proportional to enzyme concentration [E].
It undergoes a conformational change.
10^8 to 10^9 M^-1 s^-1.
Km.
By phosphorylation.
At early reaction times, [P] is negligible, allowing k-2 to be ignored.
It indicates high catalytic efficiency.
Enzymes that catalyze oxidation-reduction reactions.
An example is methotrexate, which resembles the substrate of the enzyme dihydrofolate reductase.
The ES complex.
No, because they bind to the enzyme regardless of substrate presence.
Ligases catalyze the joining of two molecules with the use of ATP.
A substance that binds to a free enzyme and competes with the substrate for enzyme binding.
A + B → P + Q.
Multisubstrate reactions.
It lowers both K m and V max.
V max = k 2 [E] T, where k 2 = k cat.
-1/Km.
They increase the enzyme's activity.
v0 equals Vmax and [ES] equals [ET].
Hyperbolic Kinetics.
They indicate reaction rates.
Higher substrate concentration [S].
The apparent Km, which is the Km with the inhibitor present.
They can bind to free enzyme (E) or the enzyme-substrate complex (ES).
They affect the enzyme's activity by binding to sites other than the active site.
Increases metabolic rate and improves energy utilization.
E + S ↔ ES ↔ E + P.
v 0 = k 2 [ES].
A serine residue.
Yes, it is reversible.
1/V max decreases, while 1/K m remains unchanged.
Phosphorylation/dephosphorylation.
Serine.
Minutes to hours.
Fraction of seconds.
PFK-1 catalyzes an early step in glycolysis, which is an ATP-generating pathway.
1/V₀ vs 1/[S].
Feedback inhibition.
v0 = k2 [ES].
A regulatory site other than the active site.
The maximum rate of reaction at saturating substrate concentration.
One substrate binds and is converted to product, releasing it before the second substrate binds.
Tetramer.
The rate of ES formation equals the rate of ES breakdown.
DFP (nerve gas).
They usually have multiple subunits.
Hydrolases like chymotrypsin and acetylcholine esterase.
Enzymes accelerate reaction rates tremendously over uncatalyzed rates.
kcat = Vmax / [E] total.
It is difficult to achieve the substrate concentration needed for Vmax determination.
They decrease the maximum rate of reaction (Vmax) without affecting the Km value.
Inhibitors that bind to enzymes non-covalently and can be removed, restoring enzyme activity.
Sigmoidal curve.
Km = (k-1 + k2) / k1.
Km (binding affinity) and kcat (conversion rate).
K m remains the same.
A rectangular hyperbola.
A reversible inhibitor that binds to an enzyme at a site other than the active site, reducing enzyme activity regardless of substrate concentration.
It indicates cooperative binding and a change in enzyme conformation.
Maintains PFK-1 in the active state and increases its affinity for F6P.
Reactants, also known as substrates, bind to enzymes.
It does not affect catalytic functions.
Transcription, Translation, and Enzyme degradation.
Vmax and the absolute concentration of the enzyme.
Improves cardiovascular health, strengthens muscles, and enhances flexibility.
Hyperbolic kinetics.
It shows the relationship between enzyme-substrate complex concentration and Michaelis constant.
1/V max.
Competitive and non-competitive inhibitors.
Biological catalysts that increase the rates of chemical reactions.
y = mx + c.
No, they do not bind to the active site.
E + S ↔ ES → E + P.
k1[E][S] = k-1[ES] + k2[ES].
Frequency of enzyme-substrate collisions and speed of chemical changes during catalysis.
Km = k-1 + k2 / k1.
Ser/Thr protein phosphatase and Tyrosine protein phosphatase.
The Michaelis constant, unique for each enzyme-substrate pair.
To catalyze the addition or removal of groups to form double bonds.
The study of the rates of enzyme-catalyzed reactions under different conditions.
The curves flatten over time.
The conversion of substrate (S) to product (P).
Sequential and ping-pong mechanisms.
Inhibitors that bind only to the enzyme-substrate complex, preventing the reaction from proceeding.
v = k [A], where k is the rate constant.
It indicates better binding of the enzyme to its substrate.
A small K_m indicates a higher affinity of the enzyme for the substrate.
Total enzyme concentration.
It reflects how quickly an enzyme can catalyze the reaction from ES to E + P.
ES represents the enzyme-substrate complex.
No, they are not altered chemically.
They are often allosteric inhibitors, involved in feedback inhibition.
Reduces symptoms of anxiety and depression, and improves mood.
They involve the phosphorylation and dephosphorylation of enzymes.
They temporarily decrease enzyme activity by binding to the enzyme or the enzyme-substrate complex.
It relates to the effects of uncompetitive inhibition.
Maximum reaction velocity (Vmax) occurs.
A reversible inhibitor that competes with the substrate for the active site of the enzyme.
v = k [A][B], where k is the rate constant.
Permanent inactivation.
There is no ES formation because [P] is negligible.
No, they cannot be overcome by increasing substrate concentration.
They bind non-covalently to a regulatory site other than the active site.
They bind through non-covalent interactions and can disassociate from the enzyme.
No, they do not assemble substrates or products.
It has the opposite effect, inhibiting the enzyme's activity.
At least 150 minutes of moderate aerobic activity per week.
They lower Vmax but do not change Km.
They lower V max.
The relationship between substrate concentration and reaction rate.
Experimentally.
Most enzymes are proteins, except for a small group of catalytic RNA molecules.
Vmax = k2[ET].
kcat / Km.
One enzyme for activation and one enzyme for inactivation.
It is the maximum rate of enzyme activity, represented by kcat / Km.
It becomes k1([E] total - [ES])[S] = k-1[ES] + k2[ES].
Using sarin gas.
It changes the conformation, preventing it from proceeding to E + P.
The number of substrate molecules converted to products per enzyme per unit time.
Helps burn calories and maintain a healthy weight.
When v 0 is one half of V max.
The Michaelis constant, a measure of the affinity of an enzyme for its substrate to form the ES complex.
Stable covalent bonds.
Covalent modification is usually slower than allosteric regulation.
Causes PFK-1 to switch to the inactive state and lowers its affinity for F6P.
Compounds that bind to an enzyme and interfere with its activity.
[E] = [E] total - [ES].
Diffusion.
It is easier to extrapolate values with a straight line compared to a hyperbolic curve.
The substrate concentration at which the reaction velocity (V) is half of V max.
k cat / K m.
They affect the conformation of the enzyme.
They decrease both the maximum reaction rate (Vmax) and the Michaelis constant (Km).
[ES] is very difficult to determine.
They alter the conformation of the enzyme to affect catalysis.
Enzymes remain unchanged in the overall process.
E represents the enzyme.
Ser/Thr protein kinase and Tyrosine protein kinase.
Causes paralysis.
Products are formed as soon as the ES complex is formed.
It is defined as v0 = k2[ES].
Both substrates bind to the enzyme before any product is released.
Fructose-6-P + ATP -----> Fructose-1,6-bisphosphate + ADP.
It stabilizes the enzyme-substrate complex, making it less likely to convert to product.
K_m decreases, indicating higher affinity for the substrate.
They represent the rate constants for binding and catalysis.
They can prevent the formation of the ES complex or prevent the breakdown of ES to E + P.
Enzymes selectively recognize proper substrates over other molecules.
Yes, other enzymes may be activated by phosphorylation.
They decrease the enzyme's activity.
No, enzymes do not affect the equilibrium of reactions.
By substituting Vmax into the equation for initial velocity.
An organophosphate compound.
An inhibitor that binds to an enzyme through covalent bonds and binds irreversibly.
It indicates a faster conversion of substrate to product.
Uncompetitive inhibition.
k_1 (formation of ES complex), k_-1 (dissociation of ES complex), and k_2 (conversion of ES to product).
k_1 becomes larger, leading to a high rate of binding.
It occurs when catalysis is rapid, with product formation and release occurring immediately after the ES complex is formed.
They play crucial roles in regulating enzyme activity and can be used in drug development.
