dna-reagents
Imidazole — Complete Scientific Overview
What is Imidazole?
Imidazole is a five-membered aromatic heterocycle containing two nitrogen atoms at non-adjacent positions. It is a fundamental structure in biochemistry, pharmaceuticals, and molecular biology.
Chemical Properties
Molecular formula: C₃H₄N₂
Molecular weight: 68.08 g/mol
pKa: ~6.95
Structure: Planar, aromatic ring
Solubility: Highly soluble in water
Its pKa close to physiological pH makes it ideal for biological buffering and enzymatic systems.
Biological Role
Imidazole is a key component of the amino acid histidine, which plays a central role in:
Enzyme active sites
Proton transfer reactions
Metal ion coordination
This explains why imidazole is widely used to mimic biological interactions in vitro.
Major Laboratory Applications
1. Protein Purification (His-tag / Ni-NTA)
One of the most important uses:
Competes with histidine residues for binding to nickel ions
Used to elute His-tagged proteins from Ni-NTA columns
Typical concentrations:
10–40 mM → wash buffer
100–500 mM → elution buffer
2. Buffer Systems
Effective buffer around neutral pH
Used in enzymatic and biochemical assays
3. Enzyme Studies
Mimics histidine side chains
Used in catalytic and structural studies
4. Chemical & Pharmaceutical Industry
Precursor for antifungal, anti-inflammatory, and other drugs
Found in many bioactive molecules
Preparation Example
To prepare a 1 M imidazole solution:
Weigh 68.08 g
Dissolve in ~800 mL distilled water
Adjust pH if needed
Bring final volume to 1 L
Safety & Handling
Irritating to skin and eyes
Use gloves and eye protection
Store in a dry, cool environment