Enzyme Kinetics and Michaelis-Menten Parameters

Flashcards covering key concepts and vocabulary from the lecture on enzyme kinetics, including different Delta G values, reaction phases, Michaelis-Menten parameters (Vmax, Km), and types of protein mutations.

Overall Delta G

The change in free energy between products and reactants, which determines the direction of a reaction (exergonic if negative, endergonic if positive).

Delta G Double Dagger (ΔG‡)

Represents the activation energy or the energy barrier that a reaction needs to overcome to proceed, always a positive number, connected to the rate constant.

Enzyme Catalysis

A process where enzymes accelerate reactions primarily by lowering the transition state energy (ΔG‡).

Enzyme-Substrate (ES/EA) Complex

An intermediate complex formed when an enzyme binds to its specific substrate.

Steady State Phase

A phase in an enzyme-catalyzed reaction where the concentration of enzyme intermediates, such as the ES complex, remains constant over time, resulting in an almost linear appearance of product formation.

Product Inhibition

When a buildup of reaction product drives the enzyme-catalyzed reaction in the reverse direction, thereby slowing down the enzyme's catalytic activity.

Michaelis-Menten Kinetics

A model used for the steady state analysis of enzyme reactions to understand their behavior and derive parameters like Vmax and Km.

Vmax (Maximum Velocity)

The maximum rate at which an enzyme can catalyze a reaction for a specific enzyme concentration, attained when all enzyme active sites are saturated with substrate.

Km (Michaelis Constant)

The half-saturating substrate concentration; the amount of substrate required to achieve a reaction velocity that is exactly half of the maximum velocity (Vmax/2).

Wild Type (WT)

Refers to the natural, unmodified, or standard form of a protein relative to mutated variants.

Deletion (in protein sequence)

The removal of one or more amino acids from the primary sequence of an enzyme, which can often have disruptive effects on its secondary and tertiary structure.

Single Point Mutation

A genetic mutation involving the substitution of a single amino acid in a protein sequence at a specific position (e.g., I637A where isoleucine at position 637 is replaced by alanine).

Pseudo First-Order Conditions

Experimental conditions in enzyme kinetics where the initial concentration of substrate is so much greater than the enzyme concentration that it can be assumed to remain constant throughout the measured initial reaction period.

Total Enzyme Amount (E0)

The initial, known amount of enzyme added to a reaction mixture before the reaction begins.