Phycobilisome Structure of Porphyridium cruentum: POLYPEPTIDE COMPOSITION.

Dynamic fluorescence photobleaching of single phycobilisome complexes from Porphyridium cruentum

Effective Absorption Cross-Sections in Porphyridium cruentum: Implications for Energy Transfer between Phycobilisomes and Photosystem II Reaction Centers.

Effective absorption cross-sections for O(2) production by Porphyridium cruentum were measured at 546 and 596 nanometers. Although all photosystem II reaction centers are energetically coupled to phycobilisomes, any single phycobilisome acts as antenna for several photosystem II reaction centers. The cross-section measured in state I was 50% larger than that measured in state II.

Phycobilisomes of Porphyridium Cruentum

A procedure was developed for the isolation of phycobilisomes from Porphyridium cruentum. The cell homogenate, suspended in phosphate buffer (pH 6.8), was treated with 1% Triton X-100, and its supernatant fraction was centrifuged on a sucrose step gradient. Phycobilisomes were recovered in the 1 M sucrose band. The phycobilisome fraction was identified by the characteristic appearance of the ph...

Growth under Red Light Enhances Photosystem II Relative to Photosystem I and Phycobilisomes in the Red Alga Porphyridium cruentum.

Acclimation of the photosynthetic apparatus to light absorbed primarily by photosystem I (PSI) or by photosystem II (PSII) was studied in the unicellular red alga Porphyridium cruentum (ATCC 50161). Cultures grown under green light of 15 microeinsteins per square meter per second (PSII light; absorbed predominantly by the phycobilisomes) exhibited a PSII/PSI ratio of 0.26 +/- 0.05. Under red li...

Properties and Ultrastructure of Phycoerythrin From Porphyridium cruentum.

Phycoerythrin, a photosynthetic accessory pigment, was isolated from Porphyridium cruentum and examined by electron microscopy and disc gel electrophoresis. The absorption monomer, with maxima at 563, 545, and a shoulder at 500 nm, has a molecular weight of about 300,000. With phosphotungstic acid staining it appears as a tightly structured disc-shaped particle possessing a mean diameter of 101...