Chlorophyll-Protein Complexes from the Red-Tide Dinoflagellate, Gonyaulax polyedra Stein

Abstract

A comparision of high (330 microeinsteins per meter squared per second) and low (80 microeinsteins per meter squared per second) light grown Gonyaulax polyedra indicated a change in the distribution of chlorophyll a, chlorophyll c(2), and peridinin among detergent-soluble chlorophyll-protein complexes. Thylakoid fractions were prepared by sonication and centrifugation. Chlorophyll-protein complexes were solubilized from the membranes with sodium dodecyl sulfate and resolved by Deriphat electrophoresis. Low light cells yielded five distinct chlorophyll-protein complexes (I to V), while only four (I' to IV') were evident in preparations of high light cells. Both high molecular weight complexes I and I' were dominated by chlorophyll a absorption and associated with minor amounts of chlorophyll c. Both complexes II and II' were chlorophyll a-chlorophyll c(2)-protein complexes devoid of peridinin and unique to dinoflagellates. The chlorophyll a:c(2) molar ratio of both complexes was 1:3, indicating significant chlorophyll c enrichment over thylakoid membrane chlorophyll a:c ratios of 1.8 to 2:1. Low light complex III differed from all other high or low light complexes in that it possessed peridinin and had a chlorophyll a:c(2) ratio of 1:1. Low light complexes IV and V and high light complexes III' and IV' were spectrally similar, had high chlorophyll a:c(2) ratios (4:1), and were associated with peridinin. The effects of growth irradiance on the composition of chlorophyll-protein complexes in Gonyaulax polyedra differed from those described for other chlorophyll c-containing plant species.