After purification,my protein getting precipitated. for Cell lysis, equilibriation , wash buffer and elution buffer , used 20 mM tris HCL of pH 7.8. I set up dialysis in different percent of glycerol like 10%, 15%, 20% and 25% in maximun 1ml volume of protein, protein is not precipitated but if I increased the volume of protein upto 2ml in 1 litre 20mM tris buffer protein get precipitated even isoelectric of protein is 5.99.