Chapter 7 - Enzyme Kinematics

enzyme kinematics

the study of rates of reactions catalyzed

disappearance of substrate and appearance of product

the reaction rate (velocity) can be described what two ways?

enzyme kinematics

the study of rates of reactions catalyzed

disappearance of substrate and appearance of product

the reaction rate (velocity) can be described what two ways?

non-linear

many enzymes react with substrates in a (linear/non-linear) fashion?

hyperbolic

what is the shape of a Michael-Menten curve?

[ES] is difficult to measure

What is the problem with Michaelis - Menten Kinetics?

Michaelis - Menten

This plot describes enzyme - catalyzed reactions in terms of Km and Vmax

[ES] is constant

What is the first assumption with Michaelis - Menten Kinetics?

[S] is very high, so does not change

What is the second assumption of the Michaelis - Menten Kinetics?

Reaction does not proceed in the reverse direction

What is the third assumption regarding the Michaelis - Menten Kinetics?

measure of enzymes affinity for a substrate

What does Km stand for?

high

Low Km = _____ affinity

low

High Km = _____ affinity

catalytic rate constant

What does Kcat stand for?

catalytic efficiency

What does the formula Kcat/Km indicate?

Lineweaver Burke plot

what plot linearizes Michaelis - Menten kinetics data?

experimentally

Km and Vmax are determined _____________

Km/Vmax

the slope of lineweaver - burke plot represents what equation?

Reversible

Enzyme Inhibition:

Noncovalent bonding of small biomolecules or proteins to the enzyme subunit; Four classes - Competitive, Uncompetitive, Noncompetitive, and Mixed

Irreversible

Enzyme Inhibition:

Inhibitory molecule forms a covalent bond or very strong non-covalent bond with catalytic groups in the enzyme active site

“Kills” the enzyme by tight binding to the enzyme

Effectively reduces the entire enzyme concentration

Competitive

Type of Reversible Inhibitor where inhibitor binds only to enzyme in the active site, blocking the substrate from binding

increases; no effect

In competitive inhibition, Km _________ and Vmax _____________

Competitive

This Lineweaver burke plot shows what type of Inhibition?

Uncompetitive

Type of Reversible Inhibitor where the inhibitor binds only to the enzyme substrate complex (ES) after it is formed

decreases; decreases

In uncompetitive inhibition, Km ________ and Vmax ____________

Uncompetitive

What inhibition does this Lineweaver Burke plot show?

Noncompetitive

Type of Reversible Inhibitor where the inhibitor binds equally to E and ES complex; binds to allosteric site

no effect; decreases

In noncompetitive Inhibition, Km ________ and Vmax ________

Noncompetitive

What type of inhibition does this Lineweaver - Burke plot show?

Mixed Inhibition

Type of Reversible Inhibition where binding is mixed unequally between both enzyme and enzyme substrate

lowered

In mixed inhibition, the Km is ___________ if the inhibitor prefers the ES complex

increases

In miced inhibition, Km ____________ if the inhibitor prefers the enzyme

protease inhibitors and zymogens

If serine proteases exist in our body, why don’t we digest ourselves?

allosteric regulation

How are enzymes controlled?