Piperazine-1,4-bis(2-hydroxypropanesulfonic acid) dihydrate
[CAS# 68189-43-5]

Identification

• Classification: Chemical reagent >> Organic reagent >> Sulfonic acid / sulfinic acid
• Name: Piperazine-1,4-bis(2-hydroxypropanesulfonic acid) dihydrate
• Synonyms: POPSO; Piperazine-N,N'-bis(2-hydroxypropanesulfonic acid) dihydrate
• Molecular Formula: C₁₀H₂₂N₂O₈S₂.2(H₂O)
• Molecular Weight: 398.45
• CAS Registry Number: 68189-43-5
• EC Number: 269-199-1
• SMILES: C1CN(CCN1CC(CS(=O)(=O)O)O)CC(CS(=O)(=O)O)O

Properties

• Solubility: 0.25 g/mL (1 M NaOH)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335
Eye irritation	Eye Irrit.	2	H319

Discovery and Applications

Piperazine-1,4-bis(2-hydroxypropanesulfonic acid) dihydrate, commonly known as POPSO, is a zwitterionic buffer designed to meet the need for stable pH maintenance in biological and biochemical research. The discovery of POPSO is part of an ongoing effort to create effective buffers that meet the criteria set by Good Buffers, including minimal interactions with biomolecules, stability under a wide range of conditions, and nontoxicity.

The molecular formula of POPSO is C10H24N2O10S2, and the molecular weight is 396.43 g/mol. The structure consists of a piperazine ring linked to two hydroxypropanesulfonic acid groups, which provides excellent buffering capacity. The dihydrate form contains two water molecules, which enhances its stability in solution. POPSO is effective in the pH range of 7.2 to 8.5, and has a pKa of 7.8 at 25°C, making it well suited for buffering near-neutral to slightly alkaline conditions.

POPSO is frequently used in electrophoresis buffers, particularly for the separation of proteins and nucleic acids. Its stability and buffering capacity ensure that pH remains consistent during electrophoresis, which is critical for accurate migration and separation of biomolecules. POPSO is often used in conjunction with other buffers to achieve the desired separation characteristics.

In cell culture applications, POPSO helps maintain the pH of the culture medium within the physiological range, promoting optimal cell growth and viability. Its non-toxic nature ensures that it does not interfere with cellular processes, making it a reliable buffer for maintaining consistent experimental conditions in cell-based studies.

POPSO is used in various biochemical analyses to stabilize pH, which is critical for the activity and stability of enzymes and other biomolecules. Its ability to maintain a stable pH environment ensures accurate and reliable analytical results, making it an essential component in enzymology research and other biochemical analyses.

During protein purification, maintaining a stable pH is essential to preserve protein structure and function. POPSO is used in chromatographic techniques and other purification protocols to buffer the system, increasing the yield and purity of isolated proteins. Its compatibility with different purification methods makes it a versatile tool in protein chemistry.

In structural biology, POPSO is used in techniques such as X-ray crystallography and NMR spectroscopy to study the structure of proteins and other biomolecules. Its stability and low ionic strength make it an ideal buffer for obtaining high-quality structural data without interfering with the biomolecule being analyzed.

The high buffering capacity allows POPSO to effectively maintain a stable pH, ensuring consistent experimental results. POPSO has a wide pH range and can be used in a variety of experimental conditions, making it a versatile buffer. POPSO is generally non-toxic to cells and does not interfere with biochemical reactions, making it suitable for sensitive biological applications.

References

2020. Citrobacter diversus-derived keratinases and their potential application as detergent-compatible cloth-cleaning agents. Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology], 51(3).
DOI: 10.1007/s42770-020-00268-3

2006. Buffers. Basic Methods for the Biochemical Lab, 1(1).
DOI: 10.1007/3-540-32786-x_7