Enzymes

6 Classes of Enzymes

Oxidoreductases, Transferases, Hydrolases, Lyases, Isomerases, Ligases

Oxidoreductase Purpose

Oxidation-Reduction reaction

Transferases Purpose

Transfer of functional groups

Hydrolases Purpose

Hydrolysis reactions

Lyases purpose

group elimination to form double bonds

Isomerases Purpose

Isomerization reactions

Ligases Purpose

Bond formation coupled with ATP Hydrolysis

How is a Lineweaver-Burk plot effected with a competitive inhibitor

Km increases, Vmax is unchanged

How is a Lineweaver-Burk plot effected with an uncompetitive inhibitor

Km decreases, Vmax decreases

How is a Lineweaver-Burk plot effected with a noncompetitive inhibitor

km is unchanged, Vmax is decreased

What type of inhibitor is this?

noncompetitive

What type of inhibitor is this?

A competitive inhibitor

What type of inhibitor is this?

uncompetitive

What is a competitive inhibitor

A molecule that binds to an enzyme's active site, preventing the substrate from binding

What is a noncompetitive inhibitor

A molecule that binds to an enzyme at a site other than the active site, altering enzyme function and preventing substrate binding.

What is an uncompetitive inhibitor

A molecule that binds only to the enzyme-substrate complex, preventing conversion to the product.

Michaelis-Menten Equation

Km Equation

[E][S]/[ES]

Kcat equation

Vmax/[E]t

What is Km

the substrate concentration at which the reaction velocity is half of Vmax, indicating the affinity of the enzyme for its substrate.

What is kcat

the turnover number of an enzyme, representing the number of substrate molecules converted to product per enzyme molecule per unit time when the enzyme is fully saturated with substrate.

Catalytic Efficiency Equation

kcat/Km

What is catalytic efficiency

A measure of how effectively an enzyme converts a substrate into product. Higher values indicate more efficient enzymes.

What is the equation of a Lineweaver-Burk Plot

what is a suicide substrate

a substrate that goes to the enzymes active site but is unable to undergo the complete reaction and becomes “stuck” in the active site

Michealis-Menten equation for a competitive inhibitor

Why does Km seem larger with a competitive inhibitor

Because the inhibitor prevents some of the substrate from reaching the active site, the enzyme’s affinity for the substrate appears to decrease. However, because the inhibitor binds reversibly, it constantly dissociates from and re-associates with the enzyme, which allows a substrate molecule to occasionally enter the active site. It requires a higher substrate concentration to achieve the same enzyme activity, making it appear to have a larger Km.

equation for Ki

different mechanism of enzyme catalysis

Acid-base catalysis, covalent catalysis, metal ion catalysis