An enzyme-controlled reaction is often expressed in the following way:
The
substrate molecules (orange rectangle) diffuse in [from the left, as in the equation] and bind with the
active site of the enzyme, which is complementary in shape (
lock and key concept). This forms the
enzyme-substrate complex. The change in shape and colour of the enzyme are a hint to the
induced fit model of enzyme action. In all hydrolysis reactions,
water (represented by the small blue rectangle) participates in the breakdown, with the release of
products (red and yellow squares), which diffuse away [to the right, as in the equation]. The process continues as long as there are substrate molecules to be converted, as the enzyme molecule (green) is unchanged at the end of the reaction.