PURIFICATION AND CHARACTERIZATION OF PHYCOCYANIN FROM THE MARINE CYANOBACTERIUM SYNECHOCOCCUS SP. IO9201

This paper describes a suitable method for the optimum extraction and isolation of phycocyanin from the cyanobacterium Synechococcus sp. IO9 201 isolated from Caribbean waters. Phycocyanin from this microorganis m was purified to homogeneity and some of its properties were investig ated. The purification steps consisted of extraction, hydrophobic inte raction chromatography and ion exchange chromatography. Freezing at -2 1 degrees C-thawing at 4 degrees C, using an alkaline buffer was the b est method for extracting phycocyanin from Synechococcus sp. IO9201. T he best extraction was obtained using butyl-sepharose resin for hydrop hobic interaction chromatography and 0.05 M Tris-HCl (pH = 7) containi ng 10% ethanol for phycocyanin elution. Finally, phycocyanin was furth er purified by ion exchange chromatography using Q-sepharose and elute d with a complex isocratic system. The estimated molecular weight of t he phycocyanin purified from Synechococcus sp. IO9201 was 102000 dalto ns by gel filtration and the isoelectric point was 4.6. When analyzed by SDS-PAGE, Synechococcus sp. IO9201 phycocyanin migrated as two band s having an apparent molecular weight of 21360 and 18980 Da. The first band corresponds to beta phycocyanin subunits, whereas the second cor responds to alpha phycocyanin subunits. So, this phycocyanin was chara cterized as (alpha(CPC)beta(CPC))(3). (C) 1998 Elsevier Science Irelan d Ltd. All rights reserved.