The core application of 3- (N-morpholino) - hydroxypropanesulfonic acid (MOPSO) in enzymatic assay kits

1, Get to know MOPSO - an important member of the Good's buffer family

3- (N-morpholino) - hydroxypropanesulfonic acid (MOPSO, CAS number 68399-77-9) is a high-quality zwitterionic biological buffering reagent with the molecular formula C ₇ H ₁ NO ₅ S and a molecular weight of 225.27. Its structure is similar to MOPS, except that there is an additional hydroxyl group at the C position in the propane region, which endows MOPSO with unique buffering properties.

MOPSO belongs to the well-known "Good's buffer" family, with an effective pH buffering range of 6.2-7.6 and a pKa of 6.95 (25 ℃). This interval precisely covers the optimal reaction pH of the vast majority of clinical diagnostic enzymes (such as oxidases, esterases, peroxidases, etc.), making it an irreplaceable tool in enzymatic assay kits for in vitro diagnostics (IVD). Hubei Xindesheng Material Technology Co., Ltd. produces various types of biological buffer raw materials.

MOPSO's core physical and chemical advantages:

Strong buffering capacity: It has stable and powerful buffering capacity within the pH range of 6.5-7.5, perfectly adapting to physiological and enzymatic reaction environments;

Excellent biocompatibility: no significant toxicity to bioactive components such as enzymes and antibodies, suitable for preparing liquid reagents;

Low ion strength: contributes little to the ion strength of the reaction system, reducing interference;

High compatibility with metal ions: does not chelate with common metal cofactors such as Ca ² ⁺ and Mg ² ⁺, ensuring the activity of metal dependent enzymes;

Good water solubility: easily soluble in water, easy to prepare.

2, Typical application examples of MOPSO in enzymatic assay kits

MOPSO has been widely used in various approved enzymatic detection kits, with the following representative cases:

2.1 Cholesterol Determination Kit (Enzyme Method)

Cholesterol testing is a core component of blood lipid screening. Multiple cholesterol (CHOL) assay kits use MOPSO as the core buffer component, such as:

Cholesterol determination kit (esterase peroxidase method): Reagent 1 contains MOPSO 50 mmol/L, lipoprotein esterase, p-hydroxybenzoic acid, peroxidase; Reagent 2 contains MOPSO 50 mmol/L, 4-aminoantipyrine, and cholesterol oxidase.

Total cholesterol (TC/CHOL) assay kit (CE-CO-POD enzyme method): R1/R2 both contain MOPSO buffer, combined with MgCl ₂, DHBS, etc.

MOPSO provides a stable pH environment for cholesterol oxidase and cholesterol esterase, ensuring enzyme activity and detection precision.

2.2 Glycated Albumin Assay Kit (Enzymatic Method)

Glycated albumin (GA) reflects short-term blood glucose control levels. Representative reagent kits include:

GA-L assay kit (enzymatic method) for measuring glycated albumin ratio: GA-R1 contains MOPSO, glycated amino acid oxidase (KAOD), 4-aminoantipyrine, albumin protease, etc; GA-R2 contains MOPSO, peroxidase TOOS.

Glycated albumin assay kit (enzymatic method): R1 contains MOPSO 100 mmol/L, KAOD 12500 U/L, catalase; R2 contains MOPSO 100 mmol/L.

High concentration MOPSO (100 mmol/L) provides precise pH protection for cascade reactions of multiple enzymes.

2.3 5 '- Nuclease Assay Kit (Enzymatic Method)

5 '- nucleotidase (5' - NT) is an important serum marker for liver and gallbladder diseases. The R1 and R2 of its assay kit (enzymatic method) are based on MOPSO (pH 7.6), combined with nucleotide phosphorylase, xanthine oxidase, peroxidase, etc., to achieve multi enzyme coupling detection.

2.4 Other enzyme assay kits

MOPSO is also widely used in reagent kits for homocysteine detection (cyclic enzyme method), alpha amylase detection (IFCC method), low-density lipoprotein cholesterol determination (clearance method), and ultra sensitive C-reactive protein determination (immunoturbidimetric method), fully demonstrating its versatility and reliability.

From cholesterol to glycosylated albumin, from 5 '- NT to homocysteine, MOPSO has become an indispensable buffering component in enzymatic assay kits due to its precise buffering range and excellent biocompatibility. In the next article, we will delve into the technical reasons and key indicators for selecting MOPSO for enzyme assay kits. Please stay tuned.