|MadSci Network: Biochemistry|
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
Try the links in the MadSci Library for more information on Biochemistry.