Medical Biochemistry Enzymes: Kinetics, Inhibition & Drugs

How do enzymes increase the rate of reactions?

By lowering the activation energy required for the reaction.

list requirements for enzyme activity

substrate, pH, temperature

What is the role of co enzymes in enzymatic reactions?

they assist enzymes in catalyzing reactions and are often derived from vitamins.

What are enzyme cofactors?

Metal ions (such as Ca2+, Fe2+) that assist in the bonding of substrates in the active site.

What does the Michaelis constant (Km) represent?

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

What is the significance of a low Km when ½ Vmax?

Indicates high affinity of the enzyme for the substrate.

What is the significance of a high Km when ½ Vmax?

indicates low affinity of the enzyme for the substrate

What is a Lineweaver-Burk plot?

A double-reciprocal plot used to determine Km and Vmax of an enzyme.

What are the two main types of enzyme inhibitors?

Reversible and irreversible inhibitors.

how does a reversible enzyme inhibitor work?

it rapidly dissociates from enzyme

how does an irreversible enzyme inhibitor work?

it very slowly dissociates (very tightly bound to enzyme) can be toxic

How do competitive inhibitors work?

They bind to the active site of the enzyme, competing with the substrate, decreases reaction rate

What is the effect of non-competitive inhibitors on Vmax?

They lower Vmax but do not change Km therefore cannot overcome inhibition with more substrate

What is feedback inhibition in enzymatic activity?

A process where the end product of a metabolic pathway inhibits an enzyme involved in its synthesis.

How does temperature affect enzyme activity?

it changes can affect the 3D structure of enzymes, influencing their activity.

What is the fastest known enzyme and its reaction rate increase factor?

Carbonic anhydrase

What role does pH play in enzyme activity?

it affects the ionization state of amino acid R groups, influencing enzyme-substrate interactions.

What is the significance of the transition state in enzymatic reactions?

Enzymes stabilize the transition state, lowering the activation energy required for the reaction.

What is the effect of substrate concentration on reaction rate according to Michaelis-Menten kinetics?

At low substrate concentrations, the reaction rate is proportional to substrate concentration; at high concentrations, it becomes constant.

What is the role of ethanol in treating ethylene glycol poisoning?

it competes with ethylene glycol for binding to alcohol dehydrogenase, reducing toxicity.

What is the significance of allosteric enzymes?

They have multiple substrate binding sites and do not follow Michaelis-Menten kinetics, exhibiting cooperative binding.

What is the relationship between enzyme activity and substrate orientation?

Enzymes increase reaction rates by bringing substrates into close proximity and correct orientation.

how can drugs be used as enzyme inhibitors

penicillin prevents bacterial cell wall growth, protease inhibitors control HIV replication, inhibitors of blood cotting enzymes