Mechanisms and Inhibitors

Vocabulary flashcards covering key concepts, terms, and definitions related to enzyme mechanisms and inhibitors.

Transition State

An unstable state during a chemical reaction where reactants are converted to products.

Covalent Catalysis

A type of catalysis where a reactive group in the active site forms a temporary covalent bond with the substrate.

Nucleophile

A chemical group that donates electrons to form a chemical bond.

Electrophile

An electron-deficient species that accepts electrons from a nucleophile.

General Acid-Base Catalysis

Catalysis where a molecule other than water acts as a proton donor or acceptor.

Metal Ion Catalysis

Catalysis involving metal ions that stabilize charges or enhance substrate binding.

Catalysis by Approximation

A mechanism where two substrates are brought into proximity to enhance reaction rates.

Binding Energy

The energy released when an enzyme binds its substrate, maximizing in the transition state.

Endotherms

Organisms that maintain a constant body temperature regardless of the environment.

Ectotherms

Organisms that depend on environmental temperatures to regulate body temperature.

Optimal pH

The pH level at which an enzyme exhibits maximum activity.

Ionizable R Groups

Amino acid side chains that can gain or lose protons, affecting enzyme activity.

Enzyme Inhibition

A process where specific molecules reduce the activity of enzymes.

Reversible Inhibition

Inhibition that can be reversed, characterized by the dissociation of the enzyme-inhibitor complex.

Irreversible Inhibition

Inhibition that leads to permanent loss of enzyme activity, often through covalent bonding.

Competitive Inhibition

A type of inhibition where the inhibitor competes with the substrate for the active site.

Uncompetitive Inhibition

Inhibition where the inhibitor binds to the enzyme-substrate complex, preventing catalysis.

Noncompetitive Inhibition

Inhibition where the inhibitor can bind to the enzyme or enzyme-substrate complex, decreasing overall reaction rate without affecting substrate binding.

Transition-State Analogs

Compounds that resemble the transition state of a reaction and can inhibit enzyme activity.

Group-Specific Reagents

Irreversible inhibitors that modify specific amino acid side chains.

Affinity Labels

Compounds resembling the substrate that bind covalently to the active site of an enzyme.

Mechanism-Based Inhibitors

Inhibitors that bind to the enzyme as a substrate and are processed through the normal catalytic mechanism, leading to irreversible inhibition.

Penicillin

An antibiotic that irreversibly inactivates the enzyme involved in bacterial cell wall synthesis.

Chymotrypsin

A proteolytic enzyme that cleaves peptide bonds next to aromatic amino acids.

Michaelis-Menten Kinetics

A model that describes the rate of enzyme-catalyzed reactions and their dependence on substrate concentration.

Catalytic Triad

A set of three amino acids in an enzyme that are crucial for its catalytic activity.

Acyl-Enzyme Intermediate

A covalently bound complex formed during enzyme catalysis where the acyl group of the substrate is attached to the enzyme.

Tetrahedral Intermediate

A high-energy, unstable intermediate formed during the cleavage of a peptide bond.

Oxyanion Hole

A region in an enzyme's active site that stabilizes the tetrahedral intermediate of a reaction.

Deacylation

The process by which the acyl-enzyme intermediate is hydrolyzed, leading to the release of products.

Chymotrypsin Activity Monitoring

The measurement of enzyme activity using substrates that produce colored products upon reaction.

Proteolytic Enzymes

Enzymes that catalyze the breakdown of proteins into peptides and amino acids.

Suicide Inhibition

A type of irreversible inhibition where the inhibitor is processed by the enzyme into a reactive species that modifies the enzyme.

S1 Pocket

A binding site in enzymes like chymotrypsin where side chains of specific amino acids fit for substrate specificity.

Residues Responsible for Catalysis

Amino acids in the active site of an enzyme that play crucial roles in the catalytic mechanism.

Amino Acid Sequences

The order of amino acids in a protein, crucial for its structure and function.

Protease Reaction Mechanism

The sequence of events through which proteases cleave peptide bonds.

Catalysis Mechanism Steps

The sequential stages in enzymatic reaction involving substrate binding, transition state formation, and product release.

Electrostatic Effects

Interactions between charged groups that stabilize biomolecular structures and facilitate reactions.

Histidine Role in Catalysis

Acts as a general base or acid in many enzymatic reactions, crucial for proton transfer.