Is it feasible to boil and denature proteins before adding protein upload buffer?

Is it feasible to boil and denature proteins before adding protein upload buffer?

This is not recommended. It is not easy to mix the protein with the buffer after boiling, which may affect the electrophoresis results. Mixing the protein with the buffer before boiling is also beneficial to the denaturation of the protein. In general, the proteins should be mixed well with the sample buffer before boiling and denaturing.