Thylakoid Organization in the Chromophyte Alga Ochromonas danica: Isolation and Characterization of a New Pigment-Protein Complex.

This report describes the isolation and preliminary characterization of a new pigment-protein complex from the chromophyte alga, Ochromonas danica. The pigment-protein complex was obtained by extracting a thylakoid membrane preparation with the zwitterionic detergent lauryldimethylamine oxide followed by ultracentrifugation on sucrose gradients. The pigment-protein complex has been characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, absorption spectroscopy, and low temperature (77 Kelvin) chlorophyll fluorescence spectroscopy. A polypeptide with a monomeric molecular weight of 31,000 as determined by denaturing sodium dodecyl sulfate-polyacrylamide gel electrophoresis was the major constituent of this pigment-protein complex. The major pigment in this complex was chlorophyll a, although an as yet unidentified carotenoid was also present. There was no evidence for the presence of chlorophyll c.