powerpoint enzymes models of action
DESCRIPTION
Source: teachers.cie.org.ukTRANSCRIPT
Enzyme Action
Enzymes: proteins that function as biological catalysts.
Catalyst: a substance that speeds up a chemical reaction and is not changed by the reaction.
Lock and Key
Lock and Key
However certain substances can bind to the enzyme at sites other than theActive site and modify its activity (inhibitors/co-factors)
Idea that the enzyme is flexible
Induced Fit
Enzyme reactions
enzyme + substrate enzyme-substrate complex
Enzyme reactions
enzyme + substrate enzyme-substrate complex
E +S ES
Enzyme reactions
enzyme + productenzyme-substrate complex
E +PES
enzyme + substrate enzyme-substrate complex
E +S ES
Enzyme activity
How fast an enzyme is workingRate of Reaction
Enzyme activity
How fast an enzyme is workingRate of Reaction
Rate of Reaction = Amount of substrate changed (or amount product formed) in a given period of time.
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Enzyme activity
Variable you are looking at
Enzyme activity
Four Variables
Enzyme activity
Four Variables
Temperature
pH
Enzyme Concentration
Substrate Concentration
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Temperature
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Temperature
0 20 30 5010 40 60
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Temperature
0 20 30 5010 40 60
40oC - denatures
5- 40oC Increase in Activity
<5oC - inactive
Effect of heat on enzyme activtyIf you heat the protein above its optimal temperature
bonds break meaning the protein loses it secondary and tertiary structure
Effect of heat on enzyme activty
Denaturing the protein
Effect of heat on enzyme activty
Denaturing the protein
ACTIVE SITE CHANGES SHAPE SO SUBSTRATE NO LONGER FITS
Even if temperature lowered – enzyme can’t regain its correct shape
ph
• The ph scale measures how acidic or alkaline a substance is.
• The chemical properties of many solutions enable them to be divided into 3 categories:
1) Neutral: solutions with a ph of 7.
2) Alkaline: solutions with a ph greater than 7
3) Acidic: solutions with a ph less than 7.
Ph scale
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pH
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1 3 42 5 6 7 8 9
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1 3 42 5 6 7 8 9
Narrow pH optima
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pH
1 3 42 5 6 7 8 9
Narrow pH optima
WHY?
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pH
1 3 42 5 6 7 8 9
Narrow pH optima
Disrupt Ionic bonds - Structure
Effect charged residues at activesite
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Enzyme Concentration
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Enzyme Concentration
Enzyme Concentration
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Substrate Concentration
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Substrate Concentration
Substrate Concentration
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Substrate Concentration
Substrate Concentration
Active sites full- maximum turnover
Making use of enzymes
• Washing powders
• Food industry
• Germination of seeds
• Antibiotic penicillin
Washing powder
Biological washing powders
• Contain:
- lipase: greasy stains
- protease: eggs, blood
• Advantage: they work at lower temperatures, so less water heating is needed, and clothes don´t shrink.
Food industry
• Fruit juices: are extracted using pectinase. It breaks down pectin and is much easier to squeeze juice from the fruit. It also makes the juice clear rather than cloudy.
• Biscuits: - isomerase: converts glucose to fructose, which is sweeter so less needs to be used in slimmers biscuits.
- protease: softens glutens, making the roller of biscuits easier
Germination of seeds
• Amylase is found in seeds.
• When the seed begins to germinate, it catalyses the break down of insoluble starch to soluble maltose.
• The maltose is used by the growing embryo : -as an energy source
- to make cellulose for new cell
walls.
We obtain many enzymes from microorganisms
• Bacteria
• Microscopic fungi, such as yeast.
• They are grow inside fermenters.
• Conditions needed to grow and reproduce:?
The fungus penicillium makes penicillin
• The antibiotic penicillin is made by cultivating the fungus in a fermenter.
• The fermenter is kept at the correct ph and temperature for the enzymes of the fungus to work well. What else do they need to grow?
• Its enzymes convert a substrate to a desired product. Which one?
• First 15-24 hs. The fungus just grow.• Then, it begins to secrete penicillin, which is
collected from the liquid part of the culture.
