A novel peridinin-chlorophyll a protein (PCP) from the marine dinoflagellate Alexandrium cohorticula: a high pigment content and plural spectral forms of peridinin and chlorophyll a.

A new type of peridinin-chlorophyll a protein (PCP) was isolated from the marine dinoflagellate Alexandrium cohorticula. Unlike previous studies. PCP was obtained as a single component in the presence of a protease inhibitor. The monomer had a molecular mass of 37 kDa with 12 peridinin molecules associated with 2 chl a molecules. This pigment content was much higher than that reported previously. We observed a partial amino acid sequence of the N-terminus that is novel among photosynthetic pigment-protein complexes. Magnetic circular dichroism clearly indicated that chl a in PCP had monomeric features. Multiple spectral components were suggested for both chl a and peridinin. Based on the high pigment content, the optical properties were compared with those for a reported PCP containing 4 chl a and 1 peridinin.