Before trying optimization of culture condition, I would make sure the His tagged protein is actually expressed by WB using anti Histag antibody. If it is the case (ie. expression of insoluble protein), I would lower temperature, lower IPTG concentration in order to slow down the process and therefore favor the folding of the protein. Other aspects to explore: chaperonin coexpression, use of autoinducible medium.
Before trying optimization of culture condition, I would make sure the His tagged protein is actually expressed by WB using anti Histag antibody. If it is the case (ie. expression of insoluble protein), I would lower temperature, lower IPTG concentration in order to slow down the process and therefore favor the folding of the protein. Other aspects to explore: chaperonin coexpression, use of autoinducible medium.
Did you see the induction? Please load a gel with uninduce and induce sample. What vector you are using. Are you expressing protein of bacterial or eukaryotic origin?
You should first confirm your protein by Western blot; then, purify it. If your protein has large molecular weight, and you want it in a native status (non-denatured), you can try this solution "B-PER Complete Bacterial Protein Extraction Reagent"