Science Crit C scientific language

Catalysis

The process of increasing the rate of a chemical reaction by adding a substance that is not consumed in the reaction.

Catalytic activity

The ability of a catalyst to promote a reaction, often measured as the rate at which a substrate is converted to a product.

Substrate specificity

The tendency of an enzyme to only catalyze a specific reaction for a particular substrate.

Active site

The region of an enzyme where substrate molecules bind and undergo a chemical reaction.

Enzyme-substrate complex

The temporary complex formed when an enzyme binds to its substrate.

Induced fit model

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

Activation energy

The minimum energy required to initiate a chemical reaction.

Reaction rate / Velocity

The speed at which reactants are converted into products in a chemical reaction.

Michaelis-Menten kinetics

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

Km (Michaelis constant)

The substrate concentration at which the reaction rate is half of Vmax, reflecting enzyme affinity for the substrate.

Vmax (maximum velocity)

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

Allosteric regulation

The regulation of an enzyme's activity through binding of molecules at sites other than the active site.

Competitive inhibition

A form of enzyme inhibition where a substance mimics the substrate and competes for binding at the active site.

Non-competitive inhibition

A form of enzyme inhibition where an inhibitor binds to the enzyme at a different site, reducing its activity without competing with the substrate.

Cofactors and coenzymes

Non-protein molecules that assist enzymes in catalyzing reactions; cofactors are often metal ions, while coenzymes are organic molecules.

Enzyme saturation

A condition where all active sites of an enzyme are occupied by substrate molecules, leading to the maximum reaction rate.

Denaturation

The irreversible alteration of an enzyme's structure, resulting in loss of function, often due to extreme pH or temperature.

Optimum pH / Temperature

The specific pH or temperature at which an enzyme shows peak activity.

Enzyme assay

Laboratory procedure to measure enzyme activity.

Spectrophotometric analysis

A method that measures the amount of light absorbed by a sample to quantify specific substances or reactions.

Initial velocity (v0)

The rate of reaction when the substrate concentration is at its highest and product formation has just begun.

Lineweaver-Burk plot

A graphical representation of the Michaelis-Menten equation, used to determine Km and Vmax.

Turnover number

The number of substrate molecules converted to product by an enzyme per unit time.

Enzyme efficiency

A measure of how effectively an enzyme converts a substrate into product, often represented by the ratio kcat/Km.

Feedback inhibition

A regulatory mechanism where the end product of a metabolic pathway inhibits an upstream process.

Zymogen (proenzyme)

An inactive enzyme precursor that requires a biochemical change to become an active enzyme.

Isoenzymes

Different enzyme variants that catalyze the same reaction but differ in structure and kinetic properties.

Enzyme commission (EC) number

A numerical classification scheme for enzymes based on the reactions they catalyze.

Biocatalyst

A substance (often an enzyme) that accelerates a biochemical reaction.

Hydrolysis / Oxidation / Reduction

Types of biochemical reactions catalyzed by specific enzymes; hydrolysis involves the breakdown of compounds, oxidation involves the loss of electrons, and reduction involves the gain of electrons.

Steady-state kinetics

A condition in enzyme kinetics where the concentration of the enzyme-substrate complex remains constant over time.