Dg. Durnford et Br. Green, CHARACTERIZATION OF THE LIGHT-HARVESTING PROTEINS OF THE CHROMOPHYTICALGA, OLISTHODISCUS-LUTEUS (HETEROSIGMA-CARTERAE), Biochimica et biophysica acta. Bioenergetics, 1184(1), 1994, pp. 118-126
The light-harvesting complexes (LHC) of the unicellular marine chromop
hyte, Olisthodiscus luteus (Heterosigma carterae), were fractionated b
y sucrose-density gradient centrifugation following digitonin solubili
zation, and by non-denaturing SDS-PAGE. The sucrose gradient allowed f
or the isolation of a major light-harvesting complex fraction, contain
ing approximately 53% of the total chlorophyll, the majority of the ch
lorophyll c and a single polypeptide of 19.5 kDa. Up to 12 different l
ight-harvesting polypeptides were detected in thylakoids and in the lo
wer Photosystem I (PS I) related fractions using polyclonal antibodies
specific for barley light-harvesting complexes or a diatom fucoxanthi
n-Chl a/c complex. The non-denaturing gel system of Allen and Staeheli
n (Anal. Biochem. 194 (1991) 214-222) allowed the resolution of a numb
er of large pigment-protein complexes, an improvement over previous el
ectrophoretic separation methods applied to the chromophytic algae. Di
fferences among the light-harvesting polypeptides in apparent molecula
r mass, immunological cross-reactivity and distribution among differen
t pigment-protein complexes suggest that this protein family may be as
complex as the family of chlorophyll a/b light-harvesting polypeptide
s in green algae and higher plants.