Part 1 Flashcards
What is an enzyme and how does it work?
Enzymes catalyses reactions by decreasing the activation energy/ they can also be up regulated or down regulated which can lead to other enzyme deficiencies such as carnitine transporter deficiency.
what are the 5 different catalytic mechanisms?
- Acid - Base catalysis: Enzyme accepts or donates protons which speeds up reaction.
- Covalent Catalysis: Enzyme forms covalent bonds with the substrate.
- Metal ion catalysis: ion stabilises charge/ion causes water ionisation- becomes a better nucleophile
- Stabalizes/preferentially binds to transition state.
- Promotes and orientation of the reactants
What is a prosthetic group and what does it do and give examples?
Prosthetic groups are organic compounds with low molecular weight and bind to enzyme and participates in the reaction. E.g proton donors (NADH AND NADPH) Acetyl donors (Coenzyme A) and Methyl donors (S-adenosyl methionine. Metal ions such mg, Zn and Fe are also involved.
what is the Micheal menten equation and what does it describe?
It describes the rate at which the enzyme function sat different substrate concentrations.
What does Km represent in the Micheal Menten equation?
Km represents the concentration of the substrate that produces 50% of the maximum velocity of the enzyme
What are enzyme drug inhibitors?
These are drugs that interfere with the activity of the enzyme.
What are the different types of enzyme inhibitors?
There are reversible (competitive/uncompetitive/mixed or non competitive)
Irreversible
How does competitive Inhibitor work and its effects on Km and Vmax?
It competes with the substrates for the same binding site of the enzyme, it therefore increases Km but Vmax stays the same.
How does uncompetitive inhibitor work and its effects on Km and Vmax?
It binds with free enzyme and the Enzyme-substrate complex causing a change in the catalytic function, it does this via an allosteric mechanism. (substrate binding is unaffected) Vmax and Km both decrease.
How does a mixed inhibitor work and its effects on Km and Vmax?
It works by binding to free enzyme and ES causing a change in catalytic function via allosteric mechanism, substrate is can still bind, Vmax decreases but Km increases or decreases.
How does a non competitive inhibitor work and its effects on Km and Vmax?
It binds to both E and ES at equal quantities and causes catalytic function to change via allosteric mechanism, Vmax decreases and Km stays the same.
What is it and How does Irreversible inhibitor work and its effects on Vmax and Km?
Its a drug that binds to enzyme irreversibly, it eliminates a fraction of the enzyme. Vmax is decreased according to the proportion of enzyme eliminated. Km is remains unaffected. (sort of like non competitive inhibition).
Give examples of Competitive and irreversible enzyme inhibitors drugs
Statins - decrease blood cholesteral / Prevents atherosclerosis e.g simvastatin
Phosphodiesterase - used to treat asthma - they cause bronchial smooth muscle to relax e.g theophylline
NSADS & COX - Aspirin (irreversible inhibitor) / Ipbuprofen (competitive inhibitor) / they have anagelsic and anti-inflammatory effects.
