LINKAGES BETWEEN CHROMOPHORE AND PROTEIN IN BILIPROTEINS, .7. AMINO-ACID SEQUENCE IN CHROMOPHORE REGIONS OF C-PHYCOERYTHRIN FROM PSEUDANABAENA-W 1173 AND PHORMIDIUM-PERSICINUM

Abstract

Bilipeptides from all chromophore regions were prepared by trypsin digestion of C-phycoerythrin from Pseudanabaena W 1173 and P. persicinium. Analytical separation and quantitative determination of bilipeptides was achieved by isoelectric focusing, preparative isolation by gel chromatography and ion-exchange chromatography. Amino acid analysis revealed cysteine as the only amino acid common to all chromopeptides. Amino acid sequences were determined by Edman degradation and the dansyl-Edman technique. Sequences are different in all 5 and 6 chromophore regions, respectively. Possible homologies are discussed. A thioether linkage between ring A of the chromophore and cysteine was found in the bilipeptides (as before in biliproteins). A second linkage (serine ester) was found in only 1 peptide (CM 4.I from Pseudanabaena W 1173). This peptide absorbs as cation at a longer wavelength (559 nm) than the other bilipeptides (542-550 nm).