Enzymes: The Catalysts of Life

These flashcards cover key vocabulary and concepts related to enzyme function, structure, and regulation.

Enzyme

A biological catalyst, often a protein or catalytic RNA, that speeds up a chemical reaction by lowering the activation energy.

Activation Energy

The minimum amount of energy required to initiate a chemical reaction.

Metabolic Pathway

A series of chemical reactions occurring within a cell that lead to the conversion of a substrate into a product.

Vmax

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

Km

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

Induced Fit

A model of enzyme activity in which the active site changes shape to better fit the substrate upon binding.

Ribozyme

A type of RNA that has catalytic activity; it can accelerate chemical reactions similar to protein enzymes.

Competitive Inhibition

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

Non-competitive Inhibition

An enzyme inhibition mechanism where an inhibitor binds to an enzyme at a different site than the active site, altering enzyme activity.

Allosteric Regulation

The regulation of enzyme activity through the binding of effector molecules at sites other than the active site, which can activate or inhibit the enzyme.

Turnover Number (kcat)

The maximum number of substrate molecules converted to product by an enzyme in a given unit of time when the enzyme is fully saturated.

Feedback Inhibition

A method of metabolic control where the end product of a pathway inhibits an earlier step in the pathway to prevent overproduction.

Covalent Modification

A method of regulating enzyme activity through the addition or removal of chemical groups, such as phosphorylation or methylation.

Active Site

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

Enzyme-Substrate Complex

An intermediate formed when a substrate molecule binds to the active site of an enzyme.

Michaelis-Menten Equation

A mathematical description of the rate of enzymatic reactions, relating reaction velocity to substrate concentration.