Enzyme activity is a measure of how well an enzyme works as a catalyst.
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Catalysts - Enzymes - Temperature and pH.
An enzyme is a protein molecule.
Enzymes are used by living cells as
catalysts.
Enzymes are very specific
catalysts.
This means that one particular
enzyme
will act as a catalyst for one
particular reaction but nothing
else.
An enzyme will work best
at a particular temperature and
pH,
called its optimum conditions.
Enzymes usually work best in warm
conditions (around 40 °C)
unlike chemical catalysts which often work
best when they are very
hot.
A graph of enzyme
activity plotted against temperature is shown below.
Enzyme activity is a measure of how
well an enzyme works as a catalyst.
Above 45
°C, the enzyme starts
to be destroyed and stops working.
In these conditions the shape of the enzyme
changes and it is said to denature.
A
graph of enzyme activity
against pH would have a similar shape
but the peak (the optimum conditions)
would be at a different pH for different
enzymes.
Pepsin in the stomach
works best at pH = 2.
Amylase in the mouth works best at
pH = 7.
Rates of
Reaction Enzymes Search Questions 
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