enzyme activity - (Jun/11/2002 )

I would like to know if it's possible to measure enzyme activity in a crude extract from vegetable or do I need to separate the proteins from the other compounds (precipitation of proteins).
thanks for help

Yes and No. You can measure enzyme activity in the crude extract provided that your extract does not have any interferring factors.  Endoegnous inhibitors of enzymes can possibly affect your enzyme activity in crude extracts.  Polysaccharides present in the extracts can alter enzyme activity of glycohydrolases. Some redox substances present in crude extracts can also affect chromogenic substrates in spectrophotometric assays. Therefore, depending on enzyme to be assayed, it is advisable to use atleast partially purified protein fraction. However, a basic estimate can certainly be obtained using crude extract.