Stabilization of the colchicine-binding activity of tubulin by organic acids.

A number of carboxylic acids and organic phosphates were found to be highly effective in stabilizing the colchicine-binding activity of calf brain tubulin. The most active were glutamate, glutarate, delta-aminovalerate, glucose 1-phosphate, glucose 6-phosphate, fructose 1,6-(bis)phosphate, creatine phosphate and 6-phosphogluconate Maximum effects occurred at high concentrations. Combinations of agents were also examined, and the most effective mixture for stabilizing tubulin found thus far was the combination of 1.0 M glutamate, 100 mM glucose 1-phosphate, 1 mM GTP and 0.5 mg/ml of albumin. No loss of activity occurred over 48 h at 37 degrees C with tubulin was present at a concentration of 100 microgram/ml.