Enzymes, Part 2

These flashcards cover key vocabulary and concepts regarding enzymes, their mechanisms of action, types of inhibitors, and enzyme regulation.

Acetylcholine (ACh)

An excitatory neurotransmitter primarily in the peripheral nervous system, facilitating communication at the neuromuscular junction.

Acetylcholinesterase

An enzyme that breaks down acetylcholine into acetate and choline, regulating neurotransmission.

Sarin gas

A toxin that irreversibly inhibits acetylcholinesterase by forming a covalent bond at the active site.

Michaelis-Menten equation

A mathematical representation of enzyme kinetics that describes the rate of enzymatic reactions.

Km (Michaelis constant)

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

Kcat (turnover number)

The rate constant for the conversion of enzyme-substrate complex to product.

Competitive inhibitor

A molecule that binds to the active site of an enzyme, preventing substrate binding.

Uncompetitive inhibitor

A molecule that binds to the ES complex, affecting both Km and Vmax.

Non-competitive inhibitor

A type of inhibitor that can bind to both the enzyme alone and the ES complex.

Lineweaver-Burk plot

A graphical representation of enzyme kinetics that uses the reciprocal values of reaction velocities.

Feedback control

A regulatory mechanism where the end product of a pathway inhibits an earlier step.

Covalent modification

A type of enzyme regulation involving the addition or removal of chemical groups, such as phosphorylation.

Zymogens

Inactive precursor forms of enzymes that require cleavage to become active.

Hexokinase

An enzyme that phosphorylates glucose in the presence of ATP, demonstrating substrate-level control.

Enzyme inhibitors

Molecules that decrease enzyme activity, classified as reversible or irreversible.