Degraded Arabinogalactans and Their Binding Properties to Cancer-Associated Human Galectins.

Lukas Pfeifer, Alexander Baumann, Lea Madlen Petersen, Bastian Höger, Eric Beitz, Birgit Classen

International journal of molecular sciences 2021 Apr 14

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Galectins represent β-galactoside-binding proteins with numerous functions. Due to their role in tumor progression, human galectins-1, -3 and -7 (Gal-1, -3 and -7) are potential targets for cancer therapy. As plant derived glycans might act as galectin inhibitors, we prepared galactans by partial degradation of plant arabinogalactan-proteins. Besides commercially purchased galectins, we produced Gal-1 and -7 in a cell free system and tested binding capacities of the galectins to the galactans by biolayer-interferometry. Results for commercial and cell-free expressed galectins were comparable confirming functionality of the cell-free produced galectins. Our results revealed that galactans from Echinacea purpurea bind to Gal-1 and -7 with KD values of 1-2 µM and to Gal-3 slightly stronger with KD values between 0.36 and 0.70 µM depending on the sensor type. Galactans from the seagrass Zostera marina with higher branching of the galactan and higher content of uronic acids showed stronger binding to Gal-3 (0.08-0.28 µM) compared to galactan from Echinacea. The results contribute to knowledge on interactions between plant polysaccharides and galectins. Arabinogalactan-proteins have been identified as a new source for production of galactans with possible capability to act as galectin inhibitors.

Citation

Lukas Pfeifer, Alexander Baumann, Lea Madlen Petersen, Bastian Höger, Eric Beitz, Birgit Classen. Degraded Arabinogalactans and Their Binding Properties to Cancer-Associated Human Galectins. International journal of molecular sciences. 2021 Apr 14;22(8)