LDH purification - (Nov/03/2011 )

I have a quick question regarding LDH purification.

I was purifying LDH from beef skeletal muscle and was measuring the specific activity at each step of the purification process so that at the end of the experiment, I could calculate the fold purification of my enzyme.

Why does fold purification decrease at first, for example going from Crude to 40% ammonium sulfate supernatant?

My fold purification gradually increased after I obtained the pellet from a 60% solution of ammonium sulfate supernatant, did flow through, affinity column, etc...but what accounts for the initial decrease in fold purification and specific activity when going from Crude product through the first purification step?

you could have some inhibitors that copurify at that step, the high salt in the supernate could be inhibitory, you could be (hopefully, reversibly) partially denatured,...