What is meant by substrates of enzymatic reactions?

An enzyme is a substance that increases the rate of a
chemical reaction. The substances which take part in the reaction other than the enzyme
are known as enzyme substrates. Catalysis involves the formation of an enzyme-substrate
complex. The enzyme-substrate complex requires a lower amount of energy to undergo the
chemical reaction than the energy required by the substrates to react on their
own.

This results in many reactions able to take place in
biological systems that would not occur at the temperature and pressure found in living
cells.

Once an enzyme has facilitated the reaction between
substrates, it returns to its original state and is ready to aid another bio-chemical
reaction.