deae dextran was added to the protein mixture in the presence of peg ave mw u02dc 8 000 5 wt conc such that the final mixture contained 0 4 grams of deae dextran ave mw u02dc 500 000 u02dc 1 deae unit 3 glucose units per gram of phycocyanin determination of the precipitate composition by analysis of the supernatant indicated a phycocyanin yield of 45 wt with a 88 wt purity in the precipitate attention is directed to comparative examples e and f wherein no precipitation occurred upon the addition of either polymer alone the procedure outlined in example 12 was followed except that the peg was present at a concentration of 10 wt determination of the precipitate composition by analysis of the supernatant indicated a phycocyanin yield of 80 wt with a 40 wt purity in the precipitate while the neutral polymer peg and the hemoglobin protein are substantially dissimilar in hydrophobic hydrophilic character the nonionic character difference between peg relatively hydrophobic and the interaction product of deae dextran and phycocyanin relatively hydrophilic as indicated by the dextran backbone effected an enhancement in phycocyanin precipitation by increasing the yield indeed there was no precipitation in the absence of peg and increased precipitation at.