Isolation of allophycocyanin B from Rhodella violacea results in a model of the core from hemidiscoidal phycobilisomes of rhodophyceae

Abstract

Two ‘trimeric’ allophycocyanin complexes could be isolated from the hemidiscoidal phycobilisomes of Rhodella violacea, AP = (α∗Apα2APβ2APβ∗AP) and APB = (α∗ApαAPαAPBβ2APβ∗AP) · Lc13.5APB. The isolation was performed by combined methods of gradient centrifugation, hydroxylapatite chromatography and ‘native’ polyacrylamide gel electrophoresis. AP showed the well-known spectral characteristics of allophycocyanin without linker polypeptide. APB is characterized by its long wavelength absorbing shoulder (675 nm) and fluorescence emission (682nm), respectively. The existence of two low molecular linker polypeptides Lc12.5 and Lc13.5APB in the phycobilisomes of Rhodella violacea, their stoichiometric calculations and the localization of Lc13.5APB in allophycocyanin B facilitated the construction of a model of the phycobilisome core.