4-Morpholineethanesulfonic acid
[CAS# 4432-31-9]

Identification

• Classification: Surfactant >> Anionic surfactant >> Sulfonate type
• Name: 4-Morpholineethanesulfonic acid
• Synonyms: 2-(4-Morpholino)ethanesulfonic acid; 2-(N-Morpholino)ethanesulfonic acid; MES
• Molecular Formula: C₆H₁₃NO₄S
• Molecular Weight: 195.23
• CAS Registry Number: 4432-31-9
• EC Number: 224-632-3
• SMILES: C1COCCN1CCS(=O)(=O)O

Properties

• Solubility: 0.5 M (water 20 °C)
• Melting point: 316 °C (decomp.)

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
Specific target organ toxicity - single exposure	STOT SE	3	H335
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	4	H302
Eye irritation	Eye Irrit.	2A	H319

Discovery and Applications

4-Morpholineethanesulfonic acid, commonly known as MES, is a zwitterionic buffer that was discovered during research into developing stable, non-toxic buffers for biochemical and biological research. This class of buffers is often referred to as Good's buffers, introduced by Norman E. Good and colleagues in the 1960s. MES was developed to meet the need for a buffer that maintains a consistent pH level under a variety of experimental conditions, thereby improving the reliability and reproducibility of scientific experiments.

The molecular formula of MES is C6H13NO4S, and its molecular weight is 195.24 g/mol. It features a morpholine ring attached to an ethanesulfonic acid group. The structure of MES gives it high buffering capacity and stability, especially in the pH range of 5.5 to 7.0. MES has a pKa of 6.1 at 25°C, making it an excellent choice for experiments that require a buffer in this pH range.

MES is widely used in biochemical and molecular biology laboratories. Its main application is in buffering solutions to maintain a stable pH during enzyme reactions, protein purification, and other biochemical assays. The stability of MES across different experimental conditions ensures accurate and consistent results, which is essential for reproducible scientific research.

MES is a commonly used electrophoresis buffer, especially in the separation of nucleic acids and proteins. It is commonly used in agarose gel electrophoresis and polyacrylamide gel electrophoresis (PAGE). MES helps maintain a consistent pH during electrophoresis, ensuring that molecules migrate and separate properly, resulting in clear and interpretable results.

In cell culture, MES is used to buffer culture media to maintain the desired pH, which is essential for optimal cell growth and viability. Its non-toxic properties make it suitable for a variety of cell types, ensuring that cells remain healthy and experimental conditions remain consistent.

MES is used in a variety of biochemical assays, where maintaining a stable pH is essential for the activity and stability of enzymes and other biomolecules. Its buffering capacity ensures that assay conditions remain optimal, resulting in accurate and reliable measurements of biochemical activity.

MES is sometimes used in the formulation of drugs and other products in the pharmaceutical industry. Its buffering properties help maintain the stability and efficacy of drug formulations, ensuring that they remain effective throughout their shelf life.

The high buffering capacity makes MES effective in maintaining pH stability, ensuring consistent experimental results. The low ionic strength makes MES compatible with a wide range of biological systems and techniques without interfering with the process being studied. MES is generally nontoxic to cells and does not interfere with biochemical reactions, making it suitable for use in sensitive biological applications.

References

2007. Structural basis of the catalytic reaction mechanism of novel 1,2-alpha-L-fucosidase from Bifidobacterium bifidum. The Journal of Biological Chemistry, 282(25).
DOI: 10.1074/jbc.M702246200

2010. Cloning and characterization of a sialidase from the filamentous fungus, Aspergillus fumigatus. Glycoconjugate Journal, 27(6).
DOI: 10.1007/s10719-010-9299-9

2010. FRET detection of Octamer-4 on a protein nanoarray made by size-dependent self-assembly. Analytical and Bioanalytical Chemistry, 398(4).
DOI: 10.1007/s00216-010-3990-3