A quantitative assay for the number of chromophores on a chromoprotein; its application to phycoerythrin and phycocyanin

A non-destructive assay for the number of chromophore groups, R, associated with a chromoprotein (e.g. phycoerythrin, phycocyanin) and the molar extinction coefficient εm can be made with the aid of the chromoprpteid's particle weight, specific extinction coefficient, fluorescence lifetime, and fluorescence yield. The ε{lunate}m and R for phycocyanin and phycoerythrin were determined to be respectively 8·104l/mole cm and 26, and 1.5·104 l/mole cm and 30. The ε{lunate}m's are lower and the R's higher than those obtained previously by chemical analysis. © 1961.