BISC_312_Lecture_11_2021

Michaelis-Menten equation

A mathematical model that describes the rate of enzymatic reactions as a function of substrate concentration.

Km (Michaelis constant)

The substrate concentration at which the reaction velocity is half of Vmax; indicates the affinity of the enzyme for its substrate.

Vmax

The maximum reaction velocity achieved by an enzyme at saturating substrate concentrations.

Competitive inhibition

A type of enzyme inhibition where an inhibitor resembles the substrate and competes for binding to the active site.

Uncompetitive inhibition

A type of inhibition where the inhibitor binds only to the enzyme-substrate complex and prevents the conversion to product.

Mixed inhibition

Inhibition where an inhibitor can bind to either the enzyme or the enzyme-substrate complex, affecting both Km and Vmax.

Irreversible inhibition

A type of inhibition where an inhibitor permanently binds to an enzyme, inactivating it.

Allosteric enzymes

Enzymes regulated by the binding of effectors at sites other than the active site, resulting in conformational changes.

Substrate-level control

Regulation of enzyme activity through direct interaction between substrate and product, influencing the reaction rate.

Feedback inhibition

A regulatory mechanism where the end product of a metabolic pathway inhibits an earlier step to prevent excess production.

Cooperativity

A phenomenon in which the binding of substrate to one active site on an enzyme affects the binding affinity of additional substrate molecules to other active sites.

Catalytic efficiency

A measure of how efficiently an enzyme converts a substrate into product, often described by the ratio of kcat to Km.

Transition state

A high-energy, unstable state that occurs during the conversion of reactants into products in an enzymatic reaction.

Aspartate transcarbamoylase (ATCase)

An allosteric enzyme involved in the biosynthesis of pyrimidine nucleotides, regulated by ATP and CTP.

Ki (inhibition constant)

The dissociation constant of the enzyme-inhibitor complex, indicating the strength of the inhibitor.

Product inhibition

A form of feedback inhibition where the product of a reaction binds to the enzyme and decreases its activity.

Homoallosteric effect

Allosteric regulation where the same molecule acts as the ligand for multiple binding sites, influencing enzyme activity.

Heteroallosteric effect

Allosteric regulation where different molecules (effectors) bind to distinct sites and affect enzyme activity.

Covalent modification

A type of post-translational modification where chemical groups are added or removed from an enzyme, influencing its activity.