Principles of Biochemistry - Enzymes

Vocabulary flashcards based on key concepts from the lecture on enzyme inhibitors and regulations in biochemistry.

Enzyme Inhibitors

Substances that decrease enzyme activity.

Irreversible Inhibitors

Inactivators that permanently shut off enzyme activity, often acting as powerful toxins.

Reversible Inhibitors

Molecules that bind to enzymes temporarily, allowing them to dissociate later.

Competitive Inhibition

Inhibition where an inhibitor competes with the substrate for the active site of an enzyme.

Non-Competitive Inhibition

Inhibition where the inhibitor binds to a regulatory site, not the active site, affecting enzyme functionality.

Dihydrofolate Reductase

An enzyme that catalyzes the conversion of dihydrofolate into tetrahydrofolate, crucial for DNA and RNA synthesis.

Methotrexate (MTX)

A competitive inhibitor of dihydrofolate reductase used as an antitumor agent.

Vmax

The maximum rate of an enzyme-catalyzed reaction when the enzyme is saturated with substrate.

Km

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

Allosterism

Regulation of enzyme activity through binding of a small molecule to a site other than the active site.

Allosteric Activation

When binding of a regulatory molecule enhances enzyme activity by making the active site available.

Allosteric Deactivation

When binding of a regulatory molecule decreases enzyme activity by making the active site unavailable.

Covalent Modification

The permanent alteration of an enzyme's structure through covalent bonds, affecting its activity.

Zymogens

Inactive precursors of enzymes that require covalent modification for activation.

Cooperativity

A phenomenon where the binding of a substrate to one active site affects the activity of other active sites.

Transition State Analogue

Molecules that mimic the transitions states of substrates, often used as inhibitors.

Kinetics

The study of the rates of enzyme-catalyzed reactions.

Feedback Regulation

A mechanism in which the end product of a pathway inhibits an earlier step, regulating enzyme activity.

Proteolytic Cleavage

An irreversible covalent modification involving the breaking of peptide bonds in proteins.

Methylation

A reversible covalent modification that can regulate gene expression and cell signaling.

Phosphorylation

The addition of phosphate groups to proteins by kinases, crucial for signal transduction.

Ubiquitination

A process of tagging proteins for degradation by the proteasome.

Competitive Inhibitors

Compounds that resemble the substrate and compete for active sites on enzymes.

Non-Covalent Interactions

Forces that may influence enzyme activity, including hydrogen bonds and ionic interactions.

Kinetic Studies

Experiments aimed at understanding the rates and mechanisms of enzyme-catalyzed reactions.

Sigmoid Kinetics

A graphical representation seen in allosteric enzymes, indicating cooperative binding.