1. Prepare a reaction mixture by combining 5 µg of Protein Sample, 1 µg of rhFUT8 in the presence of 1 nmol GDP-Azido-Fucose in the Assay Buffer with the final volume of 25 µL.
2. Prepare negative controls according to step 1 but omit Protein Sample or rhFUT8 or GDP-Azido-Fucose.
3. Incubate all the reactions and the controls at 37°C for one hour.
4. To each of the samples, add 5 µL of 1 mM CuCl2, 5 µL of 20 mM Ascorbic Acid, and 5 µL of 1 mM Biotinylated Alkyne. Mix with gentle tapping.
5. Incubate all samples at room temperature for 1 hour.
6. Separate the reactions and controls by 12% SDS-PAGE.
7. Blot the gel to a nitrocellulose membrane.
8. Block the blot with 10% fat-free milk for 5 minutes.
9. Thoroughly wash the membrane with TBST buffer by changing buffer three times for a total of 45 minutes.
10. Incubate the blot with 25 ng/mL Streptavidin-HRP in 30 mL TBST buffer for 30 minutes.
11. Thoroughly wash the membrane with TBST buffer by changing buffer three times for a total of 45 minutes.
12. Detect with commercial ECL (Enhanced Chemiluminescence) reagents.