Endosidin 7, a specific inhibitor of callose synthase, organizes callose deposition during plant cytoplasmic division without affecting endosomal transport during interphase or cytoskeletal organization, preventing late cytokinesis.

callose synthase (Arabidopsis, CHAPS-extracted membranes):100 μM

Endosidin 7 (ES7) inhibits Arabidopsis callose synthase activity in a concentration-dependent manner using CHAPS-extracted membrane fractions. At 100 μM, ES7 reduces enzyme activity by approximately 50%. Enzyme kinetics indicate that ES7 acts as a mixed-type inhibitor, increasing the apparent Km and decreasing the Vmax, suggesting interaction with both the free enzyme and the enzyme–substrate complex at different affinities[1].

Endosidin 7 effectively arrests late cytokinesis in Arabidopsis seedlings. Root growth assays determined an IC₅₀ of 4.8 μM. A 2-hour treatment with 25–50 μM Endosidin 7 induces cell plate fragmentation, binucleate cells, and complete inhibition of callose deposition at the cell plate. Endosidin 7 specifically targets late cytokinesis without affecting interphase endomembrane markers or cellulose biosynthesis[1].