Isolation and characterization of a new phycoerythrin from the cyanobacterium Synechococcus sp ECS-18

Abstract

A new phycoerythrin, SCH-phycoerythrin, was purified from Synechococcus sp. ECS-18 by DEAE-Sephacel anion exchange chromatography and Sephacryl S-300 gel filtration. The protein pigment had an absorbance maximum at 542 nm and a fluorescence maximum at 565 nm. The native molecular mass was approximately 219 kDa as determined by gel filtration, and sodium dodecyl sulfate polyacrylamide gel electrophoresis demonstrated the presence of two subunits, with molecular mass of 19 and 17.9 kDa. These observations are consistent with the (alpha beta)(6) subunit composition that is characteristic of phycoerythrins. The alpha- and beta-subunits showed immunological identity by Ouchterlony double immunodiffusion with an anti-phycoerythrin antiserum. The DNA sequence of the SCH-phycoerythrin gene was determined by PCR amplification using primers based on the conserved N-terminal amino acid sequence of the alpha- and beta-subunits of phycoerythrins.