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All enzymes are globular proteins and are generally soluble in water they act as catalysts by
speeding up the reaction but do not get used up themselves. Enzymes have a specific shape
called tertiary, all the amino acids in the enzymes work together to maintain the tertiary
structure. They are large molecules and have an active site, where they catalyse. The active
site has a very specific shape. The reaction only occurs if the substrate molecule fits well into
the active site.
In a chemical reaction substrate is turned into products. E.g. the substrate maltose is
converted into products, glucose by using the enzyme maltase.
Maltose glucose + glucose
Lactose Breakdown of milk sugar
Lactose into glucose and galactose
Catalase Breakdown of hydrogen peroxide into water and oxygen.
Lipase Breakdown of fats into fatty acids and glycerol.
Amylase Breakdown of starch to glucose.
ATPase Breakdown of ATP to ADP and a phosphate group.
Protase Breakdown of proteins into amino acids.
Activation energy is the amount of energy that must be applied for a reaction to proceed.
Different reactions require different levels of activation energy. The enzymes have classified
into two models in which they work:
Lock and key model
The substrates bind to the active site, forming an enzymesubstrate complex.
Active site then breaks down substrate molecules into products.
The shape of substrate must fit into the active site like a key into lock.
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Enzyme Concentration effects
As the concentration of enzymes is increased, more active sites become
That means more enzymesubstrate complexes form so more product is
formed and the rate of reaction is increased.
If the concentration increases further, all the active sites become occupied and
the reaction can not be increased further.…read more