THE EFFECTS OF ACID TREATMENT AND CALCIUM-IONS ON THE SOLUBILITY OF CONCANAVALIN-A

The solubilities for concanavalin A from jack bean meal were determined by the sitting drop and micro-column techniques. Solubilities varied with both the measurement technique and protein preparation procedures. Freshly purified and crystallized concanavalin A showed a normal solubility behavior, except for a slight retrograde region at lower temperatures (less-than-or-equal-to 20-degrees-C) and ammonium sulfate concentrations. A salting in effect was also observed at the lower ammonium sulfate concentrations. Treatment with 1.0M acetic acid followed by recalcification lowered the solubility compared to the freshly purified protein as measured with the micro-column technique. Overall, solubilities determined by the sitting drop technique were much higher than those measured with the micro-column method, even for the same protein material and conditions. Further, the results show that protein solubilities must be determined with regard to both the bound and free concentrations of all cofactors.