Enzymes, Cofactors, and Coenzymes

A set of flashcards covering important vocabulary related to enzymes, cofactors, and coenzymes based on the lecture notes.

Enzyme

A protein that acts as a catalyst in biochemical reactions, lowering activation energy.

Cofactor

An additional component, often a metal ion, required for enzyme activity.

Coenzyme

A complex organic molecule required for enzyme activity, often derived from vitamins.

Oxidoreductases

Enzymes that catalyze the transfer of electrons.

Transferases

Enzymes that catalyze group transfer reactions between molecules.

Hydrolases

Enzymes that catalyze hydrolysis reactions, transferring functional groups to water.

Lyases

Enzymes that add groups to double bonds or form double bonds by removing groups.

Isomerases

Enzymes that transfer groups within molecules to yield isomeric forms.

Ligases

Enzymes that form bonds between molecules using ATP cleavage.

Activation Energy

The minimum amount of energy required for a chemical reaction to occur.

Saturation

The state where all active sites of an enzyme are occupied by substrate.

Vmax

The maximum rate of an enzymatic reaction when the enzyme is fully saturated with substrate.

Km

The substrate concentration at which the reaction velocity is half of Vmax.

Competitive Inhibition

An inhibitor that competes with substrate for the active site on the enzyme.

Noncompetitive Inhibition

An inhibitor that binds to an allosteric site, reducing the enzyme's activity regardless of substrate concentration.

Uncompetitive Inhibition

An inhibitor that binds only to the enzyme-substrate complex, lowering both Km and Vmax.

Feedback Inhibition

A metabolic control mechanism where the end product inhibits an upstream process.

Allosteric Enzyme

An enzyme that undergoes a conformational change upon binding of a modulator, affecting its activity.

Homotropic Enzyme

An allosteric enzyme where the substrate also acts as a modulator.

Heterotropic Enzyme

An allosteric enzyme where the modulator is different from the substrate.

Covalent Modification

An enzyme regulation mechanism that involves the addition or removal of a chemical group.

Phosphorylation

The addition of a phosphate group to an enzyme or substrate, often altering activity.

Dephosphorylation

The removal of a phosphate group from an enzyme or substrate, often reverting it to its original state.

ADP-Ribosylation

The covalent transfer of ADP-ribose onto proteins, affecting their function.

Apoenzyme

The protein component of an enzyme without its cofactors or coenzymes.

Holoenzyme

The complete and active form of an enzyme, including its cofactors or coenzymes.

Enzyme Specificity

The ability of an enzyme to select for a specific substrate over others.

Absolute Specificity

Enzymes that react with only one specific substrate.

Broad Specificity

Enzymes that can accept a range of structurally similar substrates.

Relative Specificity

Enzymes that are specific for one substrate but can act on several related substrates.

Reaction Specificity

The selectivity of an enzyme for specific reactions involving certain substrates.

Stereo Specificity

Ability of an enzyme to discriminate between different stereoisomers.

Prosthetic Group

A tightly or covalently bound coenzyme or metal ion that is essential for an enzyme's function.

Lysozyme

An enzyme that catalyzes the hydrolysis of the glycosidic bond in peptidoglycan.

Lineweaver-Burk Plot

A double reciprocal plot used to determine Vmax and Km.

Competitive Inhibitors

Substances that increase Km but do not affect Vmax.

Noncompetitive Inhibition

Substances that lower Vmax without affecting Km.