Intro to enzymes Flashcards
What are enzymes?
In simple terms enzymes are?
Catalytic power
Enzymology and medicine
Enzymes
Enzyme kinetics
How do you measure enzyme activity?
What can effect enzyme activity?
The activity of an enzyme depends on how rapidly it can process a substrate.
The rate of a reaction increases as the substrate concentration increases until a maximum is reached (Vmax)
What is the michaelis-menten kinetics?
But what is the biological significance of the constant and how do we measure it?
What is PHOSPHO1?
What is phosphocholine hydroylsis?
PHOSPHO1
Can enzyme inhibitors be irreversible or reversible?
Irreversible inhibition
- Irreversible inhibitors react with the enzyme and form a covalent adduct with the protein.
- The inactivation is irreversible.
Organophosphates
The primary mechanism of action of diisopropyl fluorophosphate (DIPF), an organophosphate pesticide is inhibition of acetylcholinesterase (AChE).
AChE is an enzyme that degrades the neurotransmitter acetylcholine (ACh) into choline and acetic acid.
Organophosphates inactivate AChE by phosphorylating the serine hydroxyl group located at the active site of AChE.
Once AChE has been inactivated, ACh accumulates throughout the nervous system, resulting in overstimulation of receptors.
Aspirin (acetylsalicylic acid)
Aspirin is an antipyretic, anti-inflammatory and analgesic
Acts by irreversibly inhibiting cyclooxygenase-1 (COX-1)
COX-1 catalyses the conversion of arachidonic acid (AA) to prostaglandin H2 (precursor for synthesis of inflammatory mediators)
Aspirin reacts with a serine residue close to the active site preventing the substrate arachidonic acid from binding
Competitive inibition and example of competitive inhibition?
A competitive drug can compete with the substrate for the active site of the enzyme.
The substance has a similar structure to that of the normal substrate.
The drug will occupy the active site and then leave it unchanged.
The action of the enzyme is slowed down by the presence of a competitive inhibitor.
A competitive inhibitor is like a key that gets though the keyhole but cannot unlock the door.
- Bacteria cannot use readily made folic acid, they must synthesize it from 4- aminobenzoic acid
- Sulphonamides are very similar in structure to 4-aminobenzoic acid and are effective antibiotics because they starve bacteria of essential folic acid
Allosteric inhibition
Why is enzymology important?
You are a doctor working in the emergency room of a hospital……
- A man is admitted who appears drunk (dizziness, headache, slurred speech, confusion). His wife states that she found him in the garden shed and thinks he has mistaken a bottle of homebrew wine for an unlabelled bottle of antifreeze she stored there earlier
- If action is not taken immediately, he will soon be suffering from acute poisoning, resulting in kidney failure…….
However, help is at hand……
Armed with a knowledge of ENZYME KINETICS YOU CAN SAVE HIM!!!
