Absorbance- and light-based solid-phase assays for CMPNeuAc:Galbeta1-4GlcNAc-R alpha-2,3-sialyltransferase

Area of Science:

• Biochemistry
• Glycobiology
• Enzymology

Background:

• Sialyltransferases play crucial roles in biological processes.
• Accurate measurement of alpha-2,3-sialyltransferase (alpha2,3ST) activity is essential for understanding these roles.
• Existing assays may have limitations in specificity or sensitivity.

Purpose of the Study:

• To develop a novel, nonradioactive, solid-phase assay for alpha-2,3-sialyltransferase (alpha2,3ST).
• To enable specific identification of the sialylated product generated by alpha2,3ST.
• To establish a sensitive and robust method for enzyme activity determination.

Main Methods:

• Immobilization of a desialylated fetuin acceptor glycoprotein on microtiter plates.
• Enzymatic transfer of sialic acid from CMPNeuAc catalyzed by alpha2,3ST.
• Detection of the sialylated product (NeuAc alpha2-3Gal beta1-4GlcNAc-R) using biotinylated Maackia amurensis leukoagglutinin (MAL).
• Quantification via absorbance or bioluminescence using streptavidin conjugates.

Main Results:

• The assay successfully and specifically identifies the sialylated product.
• Assay performance is linear with respect to time, CMPNeuAc, enzyme, and acceptor concentrations.
• Sensitivity allows measurement of as little as 0.2 microU of enzyme using the bioluminescent reagent.
• The assay is effective with crude biological samples, including human serum and cell microsomes.

Conclusions:

• A robust, nonradioactive, solid-phase assay for alpha2,3ST activity has been established.
• This assay offers high specificity and sensitivity for detecting sialylated products.
• The method is suitable for analyzing alpha2,3ST activity in various biological samples and extracts.