Re: How can the amount of catalase in Potato Tuber tissue be measured?

The amount of catalase in potato tuber tissue can be determined using 
a number of different types of assays.  As an example of one of the simpler 
methods, I would suggest you see:

Kumar, GNM and Knowles, NR (1993) Changes in lipid peroxidation and 
lipolytic and free radical scavenging enzyme activities during the aging 
and sprouting of potato (Solanum tuberosum) seed-tubers.  Plant Physiology 
102, 115-124.

	Briefly, they ground the tissue in a mortar and pestle with HEPES 
buffer at pH 7 containing Na2S2O5.  The homogenate was clarified by 
filtration and centrifugation to yield a suitable extract for assay.  The 
catalase activity was determined by adding a sample of this extract to an 
assay mixture (3 mL) containing 12 mM H2O2 in phosphate buffer at pH 6.  
The activity was detected by the decrease in absorbance at 240 nm with time 
(i.e. using a UV spectrophotometer).

	It would be difficult to determine the mass of the catalase 
present, unless you know the specific activity of pure potato catalase 
(i.e. so many units per mg of pure, 100% active enzyme).  There are other 
ways to determine the mass of catalase protein present, such as by 
immunological techniques, but you would require a specific antibody to the 
catalase, and pure catalase to calibrate the assay