Dear Kumar:

Proper biochemical characterisation of an enzyme must be done with pure samples or at least using partially purified sample but using a highly specific method to follow its activity.

Crude extract contains plenty of enzymes and consequently you can get overlapped effects.

Best wishes,

Rosa María Martínez-Espinosa

Dear Kumar,

It depends what kind of enzyme activity you wish to study: some (most, probably) might be inhibited by high ammonium sulfate concentrations, other maybe fine. I would recommend that you test both crude extract and dialyzed extract and see if (1) you get any of your desired enzyme activity and (2) if dialysis improve activity. Further purification may be needed, but i would recommend you try that first.

Best regards,

Eric Gomès.