Premium
SUBUNIT SEPARATION (α, αprime;, β) OF CRYPTOMONAD BILIPROTEINS *
Author(s) -
GuardFriar Deborah,
MacColl Robert
Publication year - 1986
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1986.tb05594.x
Subject(s) - phycocyanobilin , phycocyanin , phycoerythrin , chromophore , chemistry , urea , protein subunit , phycobilisome , photochemistry , biochemistry , chromatography , biology , cyanobacteria , flow cytometry , genetics , bacteria , gene
— Phycocyanin 645, phycocyanin 612 and phycoerythrin 545 are biliproteins isolated from the cryptomonad algae, Chroornonas species, Hemiselmis virescens and Rhodomonas lens , respectively. The protein has α and β subunits. which are separated on an ion exchange column by using a urea gradient and omitting 2‐mercaptoethanol from the solvent. This separation establishes that the α and β subunits are not joined by disulfide bonds. In addition it has recently been shown that mercaptoethanol can produce spurious results in the calculation of the chromophore contents of these biliproteins (Guard‐Friar and MacColl, 1984). The mercaptoethanol‐free experiments allow analysis of the chromophore content in a rapid and artifact‐free manner. When the ion exchange chromatography of phycocyanin 645 is manipulated by changing the type of urea gradient, two distinct a subunit fractions are obtained. These two fractions have identical visible absorption spectra but different amino acid compositions. At least two different gene products are, thus. responsible for the a subunits. The sole chromophore on the two a subunits of phycocyanin 645 is the unique 697‐nm bilin as seen in acidic urea. Its reactivity with mercaptoethanol is determined. The α subunits of phycoerythrin 545 have two different bilins: cryptoviolin and phycoerythrobilin. Phycocyanobilin is the chromophore on the α subunit of phycocyanin 612.