ABSTRACT

The cryptomonads are a groups of eukaryotic organisms found in fresh and marine water. They have some features characteristic of protozoa but also have chloroplasts which contain biliprotein, chlorophyll c2 and chlorophyll a. The absorption, fluorescence and circular dichroism (CD) spectra of these biliproteins depended on both the types of chromophores and the apoprotein-chromophore or chromophore-chromophore interactions. The visible CD spectra of the various biliproteins exhibited long-wavelength negative bands and one or two shorter-wavelength positive bands. The relocation of cryptoviolin from the ß subunit of phycocyanin where it served as a sensitizing chromophore to the a subunit of phycoerythrin where it might function as a fluorescing (f) chromophore suggested that perhaps the subunit was structurally oriented for extrinsic excitation energy transfer. The lowest-energy bilins on each isolated biliprotein were the primary f chromophores and when part of the intact system, chromophores were responsible for interprotein energy transfer.