The word enzymes means organic catalysts. Actually enzymes are organic catalysts that speeds up the rate of a biochemical reaction without being permanently altered in the process. These are present in the cells in very small amount which speed up lowering the energy of activities. The energy which is used for molecules to react each other, forming an enzyme substrate which speed up the rate of chemical reaction by lowering the amount of energy necessary to initiate a chemical reaction.

There are 2000-3000 enzymes in a cell. Actually enzymes are protein which are secreted by living cells. The function of enzymes are that they increases the rate of chemical reaction. The energy which is used in chemical reaction is called activation energy. Enzymes reduce the activation energy. So that it is possible for chemical reactions to take place in cells at normal body temperature.

Enzymes are specific catalysts only one kind of chemical reaction. An enzyme molecule has on its surface a region called an active site. The molecule that fits the active site is called its substrate very small amount of enzyme is used to catalyse relatively large quantities of substrate. Enzymes are fixed. They are not changed during the chemical reaction. Other substances are known as activators. They can enhance enzyme activity, while others called inhibitors may repress the enzymes.

The cofactor of enzyme are atoms and molecules that join with other enzymes altering their shape and making them functional. Co-enzymes are small organic enzymes that combine to enzymes molecule to make it active. Like enzymes are combine to each other. Basically vitamins and minerals that are derived from co-enzymes and they are very essential for life.

Enzymes work in specific temperature. Increases in temperature generally lead to increases in reaction rates. If are increase the temperatures these automatically decrease in reaction rates. Some enzymes are found inside cells.