Enzyme rates Flashcards
What are factors effecting rate of reaction?
Substrate concentration, enzyme concentration, temperature and pH
How does substrate concentration affect rate of collisions
If there are more substrate molecules per unit volume, there is more chance of each enzyme molecule to collide with substrate molecules per unit time.
How does rate of collisions affect rate of reaction on substrate concentration?
This causes more enzyme-substrate complexes to form per unit time, then more enzyme-product complexes to form per unit time to make more product per unit time so rate of reaction increases
What is point X?
The point of saturation
What happens at point X?
There are enough substrate molecules for each enzyme molecule to be occupied all the time and the enzyme is said to be saturated.
What happened up to point X?
Adding substrate always causes an increase in the reaction rate so the substrate is the limiting factor
What causes the rate of enzyme-catalysed reaction to not increase?
When there are enough substrate molecules to completely fill the enzyme active site
What is VMAX?
The maximal velocity which is the max rate of reaction under optimal conditions (temperature and pH) and excess substrate
What does VMAX reflect?
How fast the enzyme can possibly catalyse the reaction
What happens is substrate is continually added?
As enzyme concentration increases, so does the rate of reaction
What happens overall as temperature rises?
As temperature rises, the rate of reaction increases up to a certain point after which the temperature rise causes denaturation of the enzyme molecule.
How does temperature affect energy?
As temperature rises, kinetic energy increases so molecules move faster making collisions more likely between enzyme and substrate and have more energy.
What is the effect of enzymes being proteins?
There is an upper limit beyond which the enzymes tertiary structure becomes denatured and he enzyme becomes ineffective
What is Q10?
The temperature coefficient of a reaction which is how much the rate of reaction increases for every 10° rise in temperature
How do you calculate Q10?
The rate at one temperature divided by the second temperature which is 10 degrees before the first temperature
What does the number of Q10 mean?
If Q10 = 3, the reaction is tripling each time etc
What does a change of pH result in?
A change in pH can cause a change in the conformation or shape of protein and enzyme activity is dependant on the enzyme shape so if the tertiary structure is altered, then the activity is affected
Why is pH important to enzymes?
Most enzymes work in a narrow range of pH values and each enzyme has its own optimum pH
What is the effect of slight change in pH
The rate of reaction can decrease but it does not denature the enzyme as it can reform once the pH is restored
What does a large change in pH cause?
It may denature the tertiary structure of the enzyme
How are pH buffers used?
To prevent the pH of a reaction changing
What do changes in the pH causes?
Change in the H+ concentration which in turn will cause changes to the interactions between the R group in the active site and the substrate.
What is pH?
A measure of the concentration of H+ ions in a solution and the tertiary structure of a protein is led together by hydrogen and ionic bonds
Where is the site of action of saliva?
Mouth/throat
What is the pH of saliva?
Neutral - 7-8
What are the enzymes in saliva?
Amylase
What is the function of saliva?
To break down starch -> maltose
What is the site of action of gastric juice?
Stomach
What is the pH of gastric juice?
Acidic - 1-2
What are the enzymes in gastric juice?
Pepsin
What is the function of gastric juice?
To break down proteins -> polypeptides
What is the site of action of pancreatic juice?
Small intestine/deuodenum
What is the pH of pancreatic juice?
Slightly alkaline - pH 8
What are the enzymes in pancreatic juice?
Trypsin, lipase, amylase and maltase
What is the function of pancreatic juice?
To break down proteins -> polypeptides, triglycerides -> glycerol + fatty acids, starch -> maltose and maltose -> glucose
