4-Methylumbelliferyl phosphate (4-MUP) (4-MUP) is used as a fluorogenic substrate of alkaline phosphatases.

4-Methylumbelliferyl phosphate has a significant advantage over currently available substrates in that its useful concentration range extends to about 0.1 μM. If the concentration of 4-Methylumbelliferyl phosphate is held constant and the pH is varied, the activity of the enzyme passes through a maximum.

I. Alkaline phosphatase activity detection
1. Preparation of 4-MUP solution: Dissolve 4-MUP in an appropriate buffer, such as Tris-HCl (pH 8.0), with a concentration generally between 0.1-1 mM.
2. Add sample: Add a sample containing alkaline phosphatase (such as serum or cell lysate) to the 4-MUP solution. Adjust the final reaction volume according to the desired sensitivity.
3. Incubate the reaction system at 37°C, usually for 30 minutes to 1 hour, to allow the enzyme to dephosphorylate 4-MUP.
4. Fluorescence measurement: After incubation, measure the fluorescence of 4-methylumbelliferone by a fluorescence spectrophotometer or microplate reader, with an excitation wavelength of 360 nm and an emission wavelength of 450 nm.
5. Data analysis: The fluorescence intensity is proportional to the activity of alkaline phosphatase. By comparing with the standard curve, the enzyme activity in the sample can be quantified.
II. Application in Enzyme-Linked Immunosorbent Assay (ELISA)
1. Plate coating: Coat the antigen or antibody of interest on the microplate.
2. Add alkaline phosphatase-labeled antibody: Add the antibody or enzyme-labeled probe linked to alkaline phosphatase.
3. Add substrate: Add 4-MUP substrate after washing.
4. Fluorescence detection: After incubation, measure the fluorescence signal using a microplate reader or fluorescence plate reader with an excitation wavelength of 360 nm and an emission wavelength of 450 nm.
5. Result interpretation: Quantify the amount of antigen or antibody based on the fluorescence intensity.
III. Alkaline phosphatase detection in cell culture
1. Cell treatment: Culture cells in appropriate culture medium and treat as needed.
2. Add 4-MUP: Add 4-MUP solution to the cell culture medium.
3. Fluorescence monitoring: After incubation, use a fluorescence microscope or microplate reader for fluorescence measurement.
4. Quantitative analysis: Quantify enzyme activity by fluorescence intensity to evaluate changes in alkaline phosphatase during treatment or differentiation.
IV. Alkaline phosphatase detection in tissue sections
1. Tissue section preparation: Prepare tissue sections using conventional histological methods.
2. Add 4-MUP: Soak the sections in 4-MUP solution, usually incubated at 37°C.
3. Fluorescence microscopy observation: After incubation, use a fluorescence microscope to observe the fluorescence signal.
5. Analysis: Evaluate the activity of alkaline phosphatase by observing the fluorescence distribution and intensity in the tissue.

The above information is based on published literature. Experimental procedures should be appropriately modified to meet specific research demands.

H2O: 20 mg/mL (78.08 mM), Sonication is recommended.