WEEK 10: DRUG TARGETS, ENZYMES AND RECEPTORS

Enzymes

Globular proteins that act as catalysts to speed up chemical reactions by lowering activation energy.

Active site

The hydrophobic hollow or cleft on the enzyme's surface that accepts substrates and cofactors.

Substrate

The reactant molecule that enzymes bind to and convert into products during a chemical reaction.

Catalytic residues

Specific amino acids in the enzyme's active site that facilitate the reaction by making or breaking bonds in the substrate.

Induced fit

A model explaining how the active site of an enzyme changes shape to fit the substrate upon binding.

Reversible inhibitors

Molecules that bind non-covalently to the active site of an enzyme, blocking substrate access but allowing inhibition to be reversed.

Irreversible inhibitors

Molecules that form a permanent covalent bond with the enzyme, preventing substrate access and not allowing reversal through increased substrate concentration.

Transition-state inhibitors

Drugs designed to mimic the transition state of an enzyme-catalyzed reaction, leading to stronger binding to the enzyme compared to the actual substrate.

Allosteric inhibitors

Inhibitors that bind to an allosteric site on the enzyme, changing its shape and blocking substrate access to the active site.

Agonists

Drugs that mimic the action of a natural messenger and activate receptors by inducing the correct fit.

Antagonists

Drugs designed to block the action of natural messengers by binding to receptors and preventing activation.

Enzyme-substrate complex

The intermediate formation when an enzyme binds its substrate, facilitating the conversion to products.

Suicide substrates

Agents that become irreversible inhibitors after being processed by the target enzyme.

Acid/base catalysis

Mechanisms in which enzymes facilitate reactions through proton transfer to stabilize intermediates.

Nucleophilic residues

Amino acids within an enzyme that provide nucleophiles to aid in the chemical reaction of substrates.

Enzyme inhibition

The process by which an inhibitor decreases an enzyme's activity, potentially by blocking substrate access or altering the active site's shape.

Cofactors

Non-protein molecules that assist enzymes in catalyzing reactions, often required for enzyme activity.