Enzymes
KEY VOCABULARY!!!
Enzymes: Proteins that work as biological catalysts. They speed up chemical reactions without being changed themselves.
Substrate: The substance that an enzyme acts on to convert into a new form during the chemical reaction is the substrate.
Product: The new forms produced by this chemical reaction are is called the product.
Active Site: The part of the enzyme where the substrate joins.
Enzyme-substrate specificity: The active site for a particular enzyme is are very specific, it matches the shape of the substrate exactly. If this shape changes then the enzyme stops working. This is called
Denaturation: When the shape of enzymes active site changes so that the substrate can no longer form a bond. Remember that enzymes are not living things themselves, but simply a molecule. So enzyme do not die, they become denatured!
Optimum: The condition where enzyme activity is at its highest. For example, many cells in humans operate best at an optimum temperature of around 37ºC and an optimum pH of around pH7.
Enzymes: Proteins that work as biological catalysts. They speed up chemical reactions without being changed themselves.
Substrate: The substance that an enzyme acts on to convert into a new form during the chemical reaction is the substrate.
Product: The new forms produced by this chemical reaction are is called the product.
Active Site: The part of the enzyme where the substrate joins.
Enzyme-substrate specificity: The active site for a particular enzyme is are very specific, it matches the shape of the substrate exactly. If this shape changes then the enzyme stops working. This is called
Denaturation: When the shape of enzymes active site changes so that the substrate can no longer form a bond. Remember that enzymes are not living things themselves, but simply a molecule. So enzyme do not die, they become denatured!
Optimum: The condition where enzyme activity is at its highest. For example, many cells in humans operate best at an optimum temperature of around 37ºC and an optimum pH of around pH7.
EXAMPLE: The Enzyme Catalase
Hydrogen Peroxide (H2O2) is a chemical which is produced as a waste product of many of the chemical reactions inside living organisms. However, it is toxic for cells if it is allowed to build up. We therefore need a way of removing hydrogen peroxide. The enzyme Catalase is essential for us to do this. It converts the toxic hydrogen peroxide into the non-toxic products of water and oxygen. A single Catalase enzyme can convert millions of hydrogen peroxide molecules into water and oxygen every second! Catalase can be used easily in the laboratory as it is found naturally in foods such as potato and liver.
Enzyme = catalase
Substrate = hydrogen peroxide (H2O2)
Products = water and oxygen
H2O2 ------(catalase)-----> H2O + O2
If a small amount of catalase (inside potato for example) is added to hydrogen peroxide, you will be able to observe bubbles of oxygen forming (foam).
Enzyme = catalase
Substrate = hydrogen peroxide (H2O2)
Products = water and oxygen
H2O2 ------(catalase)-----> H2O + O2
If a small amount of catalase (inside potato for example) is added to hydrogen peroxide, you will be able to observe bubbles of oxygen forming (foam).
The effect of temperature on enzyme activity
|
The effect of Surface Area on Enzyme Activity
We saw that when the surface area of the potato is increased the activity of the enzyme also increases. For example, when students used a single piece of potato (small surface area) there was little oxygen (foam) released. When the student used the same amount of potato but mashed it (increasing the surface area) there was a lot more oxygen released. The reason for this is that as the surface area increases, more of the enzyme can access the substrate. Therefore more of the enzyme can bind with the substrate and more oxygen can be released. |