What is enzyme and what is it role in a reaction

Enzymes are biological molecules that significantly speed up the rate of the chemical reactions that take place within cells.

They function as organic catalysts.
A catalyst is a chemical involved in, but not changed by, a chemical reaction. Many enzymes function by lowering the activation energy of reactions.

They are vital for life and serve a wide range of important functions in the body, such as aiding in digestion and metabolism.

1.989×10^30 kg is the weight of the sun.