3-Morpholinopropanesulfonic acid
[CAS# 1132-61-2]

Identification

• Classification: Organic raw materials >> Carboxylic compounds and derivatives >> Halogenation, sulfonation, nitration or nitrosation of carboxylic acids
• Name: 3-Morpholinopropanesulfonic acid
• Synonyms: 3-(N-Morpholino)propanesulfonic acid; 4-Morpholinepropanesulfonic acid; MOPS
• Molecular Formula: C₇H₁₅NO₄S
• Molecular Weight: 209.26
• CAS Registry Number: 1132-61-2
• EC Number: 214-478-5
• SMILES: C1COCCN1CCCS(=O)(=O)O

Properties

• Melting point: 277-282 °C
• Flash point: 116 °C
• Water solubility: 1000 g/L (20 °C)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P305+P351+P338

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	3	H311
Acute toxicity	Acute Tox.	3	H301
Specific target organ toxicity - single exposure	STOT SE	3	H336

Discovery and Applications

3-Morpholinepropanesulfonic acid (MOPS) was developed as part of a broad effort to create zwitterionic buffers suitable for biochemical and biological research. Discovered in the mid-20th century, MOPS is a Good buffer, a group of buffering agents introduced by Norman Good and his colleagues. These buffers are designed to maintain stable pH in biological and chemical systems, which is critical for the accuracy and reproducibility of experimental results.

The molecular formula of MOPS is C7H15NO4S, and features a morpholine ring attached to a propanesulfonic acid group. This structure gives MOPS several desirable properties, including low UV absorbance, minimal reactivity with enzymes and other proteins, and good water solubility. Its pKa of 7.2 makes it an effective buffer in the physiological pH range (6.5-8.0), making it suitable for a wide range of biological applications.

MOPS is widely used as a buffer in a variety of biochemical and molecular biology experiments. Its stability and compatibility with biomolecules make it ideal for maintaining pH in cell culture media, enzymatic reactions, and electrophoresis. For example, in SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis), MOPS is used as a buffer to ensure consistent protein separation and accurate molecular weight determination.

In cell culture applications, MOPS helps maintain the pH of the culture medium, providing a stable environment for cell growth and function. This is especially important for sensitive cell lines and primary cultures, which require precise pH control for optimal growth and differentiation.

MOPS is used in protein purification protocols to help stabilize proteins and maintain their native conformation during purification processes such as chromatography. Its low reactivity with proteins ensures minimal interference with the activity and structure of the target protein.

MOPS is used in biophysical studies to examine the properties and interactions of biomolecules. Its buffering capacity ensures that experimental conditions remain constant, allowing researchers to obtain accurate data on molecular interactions, folding, and stability.

References

1994. Potential betaPP-processing proteinase activities from alzheimer's and control brain tissues. Journal of Protein Chemistry.
DOI: 10.1007/bf01901691

1998. NAD(+)-dependent isocitrate dehydrogenase from Arabidopsis thaliana. Characterization of two closely related subunits. Plant Molecular Biology.
DOI: 10.1023/a:1005923410940

1998. Molecular characterization of a single mitochondria-associated double-stranded RNA in the green alga Bryopsis. Plant Molecular Biology.
DOI: 10.1023/a:1005907310553