title: Interaction of tubulin with non-denaturing amphiphiles.
abstract: Soluble purified calf brain tubulin contains extensive and easily accessible regions capable of hydrophobic interactions. The binding of non-ionic and mild anionic detergents to this protein has been characterized by difference absorption spectroscopy and equilibrium gel chromatography with labelled ligands. Tubulin bound reversibly and co-operatively 0.42 +/- 0.05 g deoxycholate per g protein and bound octyl glucoside at a minimal stoichiometry of 0.26 g per g protein. Binding of deoxycholate and octyl glucoside perturbed the protein absorption, quenched the fluorescence, and produced a moderate change in the far u.v. circular dichroism of tubulin. These changes have been interpreted as the result of detergent binding near aromatic amino acids and the production of a structural change different from detergent-induced denaturation. Deoxycholate and octyl glucoside inhibited colchicine binding. Octyl glucoside and Triton X-100 inhibited the in vitro self-assembly of tubulin into microtubules, whereas small concentrations of deoxycholate were found to enhance microtubule formation.
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002417:Cattle; D003078:Colchicine; D003840:Deoxycholic Acid / Q000494:pharmacology*; D003902:Detergents / Q000494:pharmacology*; D005960:Glucosides / Q000494:pharmacology*; D006027:Glycosides / Q000494:pharmacology*; D008854:Microscopy, Electron; D008870:Microtubules / Q000187:drug effects / Q000648:ultrastructure*; D017830:Octoxynol; D011092:Polyethylene Glycols / Q000494:pharmacology*; D011485:Protein Binding; D013501:Surface-Active Agents / Q000494:pharmacology*; D014404:Tubulin / Q000378:metabolism*
chemical_list: D003902:Detergents; D005960:Glucosides; D006027:Glycosides; D013501:Surface-Active Agents; D014404:Tubulin; D003840:Deoxycholic Acid; C018619:octyl-beta-D-glucoside; D011092:Polyethylene Glycols; D017830:Octoxynol; D003078:Colchicine