What type of forces bind the substrate to the active site of enzyme ?
(i) Ionic bonding (ii) Hydrogen bonding (iii) van der Waals forces (iv) Reaction with functional group of enzymes

Options

A. (i),(ii) and (iv)
B. (i),(iii) and (iv)
C. (i),(ii) and (iii)
D. (i),(ii),(iii) and (iv)

Explanation

To determine the type of forces that bind the substrate to the active site of an enzyme, we can analyze the options provided:

1. **Ionic Bonding**: Enzymes often have charged amino acid residues at their active sites. When a substrate approaches, the oppositely charged groups can attract each other, forming ionic bonds. This is a common interaction in enzyme-substrate binding.

2. **Hydrogen Bonding**: Hydrogen bonds can also form between the substrate and the amino acids in the active site. These occur when a hydrogen atom covalently bonded to a highly electronegative atom (like oxygen or nitrogen) interacts with another electronegative atom.

3. **Van der Waals Forces**: These are weak attractive forces that can occur between all molecules, including the substrate and the enzyme. Although they are weaker than ionic and hydrogen bonds, they still play a role in stabilizing the enzyme-substrate complex.

4. **Reaction with Functional Groups of Enzymes**: This option suggests the formation of strong covalent bonds between the substrate and the enzyme. However, for the enzyme to catalyze the reaction effectively, the binding must be temporary, and strong covalent bonds would hinder this process.

Based on this analysis, the correct types of forces that bind the substrate to the active site of the enzyme include ionic bonding, hydrogen bonding, and van der Waals forces. The reaction with functional groups typically leads to covalent bonding, which is not favorable for the temporary binding required for enzyme activity.

### Final Answer:
The forces that bind the substrate to the active site of the enzyme are:
- (i) Ionic bonding
- (ii) Hydrogen bonding
- (iii) Van der Waals forces