Enzyme Kinetics Flashcards
(41 cards)
What is an Enzyme (E) ?
Protein catalyst
What are Catalysts ?
They speed up reaction without being changed by the reaction
What is a Substrate (S) ?
Reactants in the enzyme catalysed reaction
What is an Active Site ?
Area of the enzyme where substrate binds
How these reactions are controlled and how fast they proceed defines ? give examples
The state of the organism e.g.
- Metabolically active - series of enzyme catalysed reactions are occurring
- Metabolically inactive - the enzyme is slowed down
What can malfunctions in enzyme reactions lead to ? give examples
It can lead to diseases e.g.
- Gout - Xanthine oxidase Catalyses hypoxanthine to H202 and then Xanthine to Uric acid which accumulates in joints
- Porphyria - involves ALA synthase mutations – X-linked disease. Enzyme involved in the synthesis of HEME pathway
- Type 1 Albinism - an eye condition, mainly in males. Tyrosinase enzyme involved in production of melanin (pigment)
- Haemopholia A - FACTOR VIII is a blood clotting factor
What do drugs often do to the enzyme activity ?
It often alters the enzyme activity
What does HIV1 protease target ?
Target for AIDS therapy
What do drugs mimic ?
They mimic a protein chain, but they can not be cleaved by the enzyme and they block activity
Why is HIV1 protease needed ?
HIV1 protease is needed for HIV growth as HIV produces a long polypeptide chain composed of many proteins. The protease then cleaves the protein chain into individual functional proteins
Enzymes are involved in ?
All biological processes
Catalysis offers ?
Control
What is Catalysis ? and what does it need to overcome ? then what does the Enzyme form ?
The acceleration of a chemical reaction by a catalyst. It has to overcome the activation energy which is done by adding an enzyme which lowers it.
Enzyme forms a transition state
Explain an Energetically Favourable Reaction ? and how does the reaction occur ?
The free energy of Y is greater than the free energy of X. Therefore ΔG<0, and the disorder of the universe increases during the reaction X → Y.
And this reaction can occur spontaneously
Explain an Energetically Unfavourable Reaction ? and how does the reaction occur ?
If the reaction X → Y occurred, ΔG would be >0, and the universe would become ordered.
And this reaction can occur only if it is coupled to a second energetically favourable reaction
Define Entropy: 2nd law of thermodynamics ?
Measure of disorder of a system
Explain why Total entropy (S) can never decrease over time for an isolated system ?
The entropy of an isolated system spontaneously evolves toward thermodynamic equilibrium: the entropy should stay the same or increase.
Give the dissociation rate ?
dissociation rate = dissociation rate constant x concentration of AB
Give the association rate ?
association rate = association rate constant x concentration of A x concentration of B
What does binding of enzyme to substrate provide ?
It provides a transition rate.
results in enzyme-product complex (EP)
What happens in an induced fit model ?
It results in a conformational change. Then the enzyme goes back to its original shape
To understand specificity of the active site we need to think about ?
The protein structure
Name some of these ?
- DNA Topoisomerase inhibitors (anticancer)
- Angiotensin converting enzyme inhibitors (blood pressure)
- Xanthine oxidase inhibitors (gout)
- HIV proteinase inhibitors (antiviral)
Enzyme increases ? and reduces ?
It increases the rate of reaction and reduce the activation energy of a reaction making it more rapid
