Isolation and characterization of an oxygen evolving photosystem 2 core complex from the thermophilic cyanobacterium Mastigocladus laminosus

V. M. Ramesh*, A. Fish, D. Michaeli, N. Keren, I. Ohad, L. Vorchovsky, R. Nechushtai

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

A novel purification procedure was developed for the isolation of oxygen evolving photosystem 2 (PS2) from Mastigocladus laminosus. The isolation procedure involves dodecyl maltoside extraction followed by column chromatography using anion exchange resins. The isolated PS2 reaction center (RC) was analyzed for its biochemical and biophysical characteristics. Analysis by SDS polyacrylamide gel electrophoresis revealed that the complex contained five intrinsic membrane proteins (CP 47, CP 43, D1, D2, and cyt b559) and at least three low molecular mass proteins. The complex exhibited high rates of oxygen evolution [333 mmol(O2) kg-1(Chl) s-1] in the presence of 2.5 mM 2,6-dimethylbenzoquinone (DMBQ) as an artificial electron acceptor. The red chlorophyll a absorption peak of this complex was observed at 673.5±0.2 nm. The isolated PS2 core complex was free of photosystem 1 as inferred from its SDS-PAGE and fluorescence spectrum. The electron transfer properties of the Mastigocladus cells and the purified PS2 core complex were further probed by measuring thermoluminescence signals, which indicated the presence of a primary quinone electron acceptor (QA) in the purified PS2 core complex.

Original languageAmerican English
Pages (from-to)355-361
Number of pages7
JournalPhotosynthetica
Volume40
Issue number3
DOIs
StatePublished - 2002

Keywords

  • 2,6-D3imethylbenzoquinone
  • Fluorescence
  • Membrane proteins
  • Oxygen evolution rate
  • Reaction center
  • Thermoluminescence

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