Video Transcript
The enzyme in the diagram has had
its active site irreversibly changed. What scientific term describes this
change?
To answer this question, let’s
start by defining what an enzyme is and then take a closer look at its structure and
how this structure can change.
An enzyme is a biological catalyst
that speeds up the rates of reaction by reducing the energy that is required for a
certain reaction to occur. Each enzyme has a specific shape
that is complementary to a particular substrate or substrates. During a biochemical reaction, the
substrate or substrates bind to a region of the enzyme called the active site, which
we can see in the diagram here. This reaction will produce a
product or products that are then released from the active site.
Enzymes are not used up during
chemical reactions and can be reused many times. However, they are not
indestructible. All enzymes have a specific optimum
temperature and pH at which they function most effectively. When conditions are not optimal,
such as high temperatures or a pH that is considerably higher or lower than this
enzyme’s optimum, the enzymes begin to change shape. This can lead to a dramatic change
in the shape of the enzyme’s active site, as we can see in the diagram.
This change in the shape of the
active site, which is usually irreversible, is called denaturation. Substrates can no longer bind to a
denatured enzyme as the active site is no longer a complementary shape. This causes the rate of the
specific enzyme-catalyzed reaction to decrease, because these enzymes are no longer
available to catalyze them.
We have found the correct answer to
this question. The scientific term that describes
the irreversible change in shape of an enzyme’s active site is denaturation.
