title: Characteristics of an R-phycoerythrin with two γ subunits prepared from red macroalga Polysiphonia urceolata.
abstract: An R-phycoerythrin (R-PE) was isolated by gel filtrations on Sepharose CL-4B and Sephadex G-150 from the phycobiliprotein extract of the marine red macroalga Polysiphonia urceolata Grev and further purified by ion exchange chromatography on DEAE-Sepharose Fast Flow. The purified R-PE showed three absorption peaks at 498 nm, 538 nm, 566 nm and one fluorescent emission maximum at 577 nm. Although the R-PE showed a single band on the examination by native PAGE, it exhibited two very close bands at pH about 4.7 in native isoelectric focusing (IEF). Polypeptide analysis of the R-PE demonstrated that it contained four chromophore-carrying subunits, α18.2, β20.6, γ31.6 (γ'), γ34.6 (γ), and no colorless polypeptide; its subunit composition was 6α18.2:6β20.6:1 γ31.6:2γ34.6. The α and β subunits were distributed within a acidic pH range from 5.0 to 6.0 in denaturing IEF and the γ subunits were in a basic pH range from 7.6 to 8.1. These results reveal that the prepared R-PE may exist in two hexamers of γ (αβ)3 γ (αβ)3γ' and γ (αβ)3 γ'(αβ)3 γ and that the R-PE participate in the rod domain assembly of P. urceolata phycobilisomes by stacking each of its trimer (αβ)3 face-to-face with the aid of one γ subunit (γ or γ').
authors.affiliation: College of Life Sciences, Yantai University, Yantai, Shandong, P. R. China.
authors.forename: Lu
authors.initials: L
authors.lastname: Wang
authors.affiliation: College of Photo-electronic Information Science and Technology, Yantai University, Yantai, P. R. China.
authors.forename: Shumei
authors.initials: S
authors.lastname: Wang
authors.affiliation: College of Life Sciences, Yantai University, Yantai, Shandong, P. R. China.
authors.forename: Xuejun
authors.initials: X
authors.lastname: Fu
authors.affiliation: College of Life Sciences, Yantai University, Yantai, Shandong, P. R. China.
authors.forename: Li
authors.initials: L
authors.lastname: Sun
mesh_terms: D058086:Microalgae / Q000737:chemistry*; D010799:Phycoerythrin / Q000737:chemistry*; D021122:Protein Subunits / Q000737:chemistry*; D000461:Rhodophyta / Q000737:chemistry*
chemical_list: D021122:Protein Subunits; D010799:Phycoerythrin