Physicochemical characteristics of interaction of toxic triterpene glycosides from holothurians with rat brain Na⁺-K⁺-ATPase

I. A. Gorshkova, A. I. Kalinovsky, S. G. Ilyin, B. A. Gorshkov and V. A. Stonik. Physicochemical characteristics of interaction of toxic triterpene glycosides from holothurians with rat brain Na⁺-K⁺-ATPase. Toxicon 27, 937-945, 1989.-High-angle X-ray diffraction spectra showed that triterpene glycosides form crystalline complexes with membrane cholesterol. Electron microscopy demonstrated a decreased vesicle size, of the membrane preparation from rat brain which is enriched in Na⁺-K⁺-ATPase, by the triterpene glycosides. The Arrhenius plot was linear in the presence of triterpene glycosides. The half-width of the phosphatidylcholine N-methyl proton line in proton NMR spectra was not altered in the presence of marine glycosides. The excimer formation of pyrene, a hydrophobic fluorescent probe, was significantly decreased by triterpene glycosides. The increase of tryptophanyl residue fluorescence demonstrated a change of the Na⁺-K⁺-ATPase conformation after treatment with cytotoxic glycosides.