Lesson 6 - Modulation and Cooperativity Flashcards
What is an allosteric enzyme?
It is an enzyme that can have its activity altered by a ligand called a modulator
Where do modulators bind on a allosteric enzyme?
They bind at secondary binding sites away from the active site
What are allosteric modulators?
They are ligands that bind to an area of the protein that is not the active site, leading to a conformational change in the proteins
This alters the affinity of the enzyme to the substrate
What is the meaning of affinity?
The attractive force binding atoms in molecules; the tendency to combine and form bonds in a chemical reaction
What is non competitive inhibitors now known as?
Allosteric negative modulators
What is competitive inhibition?
A competitive inhibitor makes use of the same active site that the substrate needs. It takes the place of the substrate, excluding it for the active site
What is the impact of inhibitors on enzyme kinetics?
Inhibitors reduce the maximum rate of a chemical reaction without changing the bind affinity of the protein for the substrate
What happens with proteins if they have a quaternary structure?
they show cooperativity in which changes in binding at one subunit alter the affinity of the remaining subunits
Give an example of cooperativity
When oxygen binds to haemoglobin
How does pH affect oxygen and haemoglobin
Exercise increases body temperature and produces C02 acidifying the blood. This leads to a reduction in the oxygen saturation of haemoglobin
This allows more oxygen to be released to the tissues when they need it
What is the Bohr effect?
As cells respire aerobically, they increase the concentration of carbon dioxide in their surrounding environment
Respiration also increases temperature as a result of the hear produced
CO2 carbon dioxide causes the blood and immediate environment around respiring cells to become acidic as carbonic acid forms
Both an increase in temperature and a decrease in pH cause a right shift in the oxyhaemoglobin dissociation curve
This ensures that oxyhaemoglobin releases oxygen to respiring body cells more easily
As the haemoglobin returns to the lungs the CO2 concentration decreases as a result the affinity for oxygen increases. This ensures that maximal oxygen uptake can be achieved
What is the Bohr effect?
Change in the pH of blood which changes the affinity of oxygen to haemaglobin allowing the transport of oxygen around the body
