How will protein respond in electrophoretic system, should pH become lower than isoelectric point of protein?

Answer 1

usually you use SDS PAGE which is negatively charged. but otherwise normally you would want a high pH above the pI so that protein is negatively charged and going to positive charge.
Main thing is that that you don't want pH=pI otherwise you will have zero charge and no movement at all.

Answer 2

It should NOT be equal to the isoelectric point either higher or lower. At the isoelectric point no move