Precipitation of S,M, X and Y potato viruses by polyethyleneglycols with different molecular weights

The minimum concentration of polyethyleneglycol (PEG) with molecular weights 4000, 6000, and 15000 necessary for precipitation of S, M, X and Y potato viruses was determined. An excessive amount of PEG causes the precipitation of other protein compounds from potato leaf cell sap. In order to obtain highly purified samples, it is necessary to use just the minimum sufficient amount of PEG. Using the minimum quantity of PEG is, also, advisable from an economical point of view. The minimum concentration of PEG of given molecular weight differs for different potato disease viruses. The concentration of PEG necessary for precipitation of a given potato virus depends on the molecular weight of PEG used—4000, 6000 and 15000. As the molecular weight increases, the concentration of PEG necessary for precipitation decreases.