Enzymes

Enzymes

Definition:

Are biological catalyst that increase the rate of biochemical reactions

The chemical nature of enzymes:

• Enzymes are proteins 
• Some enzymes are ribonucleic acids in nature.

General features of enzymes:

•  Highly efficient: 

1. Gives 10³-10⁸ product per second.
2. Act at 37°C.
3. Don’t consumed or changed during the chemical reaction.

• Specific (reaction and substrate(s))

1. Absolute specifity (one substrate)
2.  Reaction specifity (functional group)
3.  Relative specifity (a group of compounds)

• Structure of enzyme:

1. Simple protein
2. Conjugated protein

Active enzyme =   protein part + non protein part

Holo enzyme         (apoenzyme)         (cofactor)  

                       

Prosthetic group:

1. Tightly bound to enzyme
2. Organic (FMN) or metal (Zn, Mg, Mn ,Cu)
3. Majorly they are metal (metalloenzymes)
4. Stable

The role of active site :

• Binding of substrate
• Catalytic role of the enzyme

Determine the specificity of enzyme Specificity :

•  Lock and key model
• Induced fit model

How enzymes increase the rate of biochemical reaction ?

• Decrease the energy of activation .
• Equilibrium of reaction
• Increase attaining to equlibrium but do not affect the equilibrium of reaction.

Classification of enzymes :

• Oxidoreductases: transfer of electron
• Transferases       : transfer of groups
• Hydrolases         : hydrolysis
• Lyases                : break down of the bonds
• Isomerases         : convert one isomer to the other
• Ligases              : formation of C-C, C-N, C-O, C-S