Question

The active site is ? (Pick only one)

the molecule to be changed

the energy needed to make a reaction go

the agent that changes the rate of a reaction

the part of enzyme that binds the substrate

the capacity to do work

Answer 1

Answer. Option 3

Enzymes are biological catalysts which influence the rate of reaction. Most of the enzymes are protein, although some are RNA also.

An active site in an enzyme is its part which binds to the substrate.

Some of the enzymes require additional molecules to aid in the reaction to be catalyzed. These are cofactors (metal ions) or coenzymes (NAD+, FADH, etc).

Holoenzyme = Apoenzyme + cofactor/ coenzyme

Enzymes are classified into 6 categories according to the reactions they catalyze -

• Oxidoreductases
• Transferases
• Hydrolses
• Lyases
• Isomaerases
• Ligases

Enzymes although influence the reaction rates, but they do not affect the equillibrium.

Upon binding to th enzyme, the enzyme substrate complex attains a transition state which then decays to give the product. The transistion state is a higher energy state and so energy must be provided to reach the transition state. This energy is called the activation energy.

Enzymes act by lowering the activation energy by providing an alternative path which has a lower activation energy.