Enzymes are used to act as catalysts. They are proteinic in nature. Enzymes do not take part in chemical and biological activities but they increase and make efficient the rate of reaction. The functional specificity of every enzyme is the consequence of its specific chemistry and configuration. Any factor that can alter the chemistry and shape of an enzyme can affect its rate of catalysis. Some of the factors are more important to affect the rate of reaction.

There are many factors which effects the rate of enzyme reaction:
Concentration of enzyme
Concentration of substrate
Temperature
Ph of Medium
Inhibitors
A very less amount of enzyme can be useful to make a large increase in reaction. Higher the concentration of enzyme will increase the reaction rate but after a certain limit it will not increase the reaction any more.If the enzymes concentration will be constant but constantly increase in substrate amount it will increase the reaction rate.Temperature increase the enzyme reaction but at very high temperature like 70 degree centigrade enzymes activity stops.Every enzyme functions over a very narrow range of ph value.