Colchicine binding to tubulin from brain homogenates in the presence of sugars, glycols and metal ions. Effect of nickel ions on the tubulin solubility.

ABSTRACT

The fact that glycerol preserves microtubules from depolymerizing in vitro, and that some ions such as Ca(II) and Mg(II), regulate the assembly-disassembly process of these structures, induced us to study the effect of several sugars, glycols and metal ions on solubility and colchicine affinity of tubulin in rat brain homogenates, and of purified microtubular protein. Inhibition of colchicine binding was significant with glycerol, polyethylene glycol 1000 (PEG-2) and the ions Al(III), Co(II), Ni(II), while compounds structurally related to glycerol (glucose and sucrose) did not inhibit it. Mannitol, instead, increased the activity a 47