Guanidine hydrochloride
[CAS# 50-01-1]

Identification

• Classification: Chemical reagent >> Organic reagent >> Guanidine salt
• Name: Guanidine hydrochloride
• Molecular Formula: CH₅N₃.HCl
• Molecular Weight: 95.53
• CAS Registry Number: 50-01-1
• EC Number: 200-002-3
• SMILES: C(=N)(N)N.Cl

Properties

• Density: 1.34
• Melting point: 179-186 °C
• Water solubility: 2280 g/L (20 °C)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H315-H319
• Safety Statements: P261-P264-P264+P265-P270-P271-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P317-P321-P330-P332+P317-P337+P317-P362+P364-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	4	H332
Eye irritation	Eye Irrit.	2A	H319
Acute toxicity	Acute Tox.	4	H312
Specific target organ toxicity - single exposure	STOT SE	3	H335

Discovery and Applications

Guanidine hydrochloride (GdnHCl) is a potent chaotropic agent that is widely used in biochemistry and molecular biology. The compound has the chemical formula CH5N3•HCl and was first synthesized in the late 19th century. Its discovery stemmed from the study of guanidine, a compound found in guano, which led to the development of its hydrochloride salt to improve solubility and stability. Researchers soon realized its unique properties, making it a valuable tool in a variety of scientific applications.

Guanidine hydrochloride consists of a guanidine molecule with a central carbon atom double-bonded to a nitrogen atom, single-bonded to two other nitrogen atoms, and paired with a chloride ion. This structure gives it high solubility in water, allowing it to interact effectively with biomolecules. GdnHCl is a white crystalline solid that is hygroscopic and highly soluble in water and alcohol, making it easy to handle in a laboratory setting.

GdnHCl denatures proteins by disrupting hydrogen bonds and hydrophobic interactions, which causes the protein structure to unfold. This denaturation is essential for studying protein folding and stability and for refolding proteins from inclusion bodies in recombinant protein production. After denaturation, GdnHCl can be gradually removed to study the protein refolding process, providing insights into the mechanisms of protein folding and misfolding, which is critical to understanding diseases associated with protein aggregation.

The chaotropic effect of guanidine hydrochloride involves disrupting the hydrogen-bonding network of water molecules, thereby disrupting the native conformation of proteins and nucleic acids. This disruption results in unfolding of proteins and denaturation of nucleic acid structures, facilitating their study and manipulation in a variety of biochemical and molecular biology applications.

GdnHCl is used in RNA extraction protocols to inhibit ribonucleases (RNases) that degrade RNA. Its chaotropic properties denature RNases, ensuring the integrity of RNA samples for downstream applications such as reverse transcription and sequencing.

In molecular biology, GdnHCl is used in DNA purification procedures to remove proteins and other contaminants. Its ability to denature proteins facilitates the isolation of high-purity DNA for cloning, sequencing, and other genetic analyses.

GdnHCl is used to temporarily inactivate enzymes, allowing researchers to study their mechanisms of action and interactions with substrates and inhibitors. This application is critical in enzymology and drug discovery.

Guanidine hydrochloride is considered hazardous and should be handled with care. It is irritating to the skin, eyes, and respiratory tract. Appropriate personal protective equipment, including gloves and goggles, should be used. In addition, guanidine hydrochloride solutions should be prepared in a well-ventilated area or under a fume hood to avoid inhalation of dust or vapors.

References

1987. Conformation, stability, and folding of interleukin 1β. Biochemistry.
DOI: 10.1021/bi00386a048

1991. Anomalous stimulation of Escherichia coli alkaline phosphatase activity in guanidinium chloride. The Journal of Biological Chemistry.
DOI: 10.1016/s0021-9258(19)67751-0