Origin of the 77 K variable fluorescence at 758 nm in the cyanobacterium Spirulina platensis

Shubin, Vladimir; Murthy, S. D. S.; Karapetyan, N. V.; Mohanty, Prasanna

doi:10.1016/s0005-2728(05)80115-x

Cited by 83 publications

(50 citation statements)

References 19 publications

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“…1) contain at least five times more PSI than PSII, and spectral properties of the membranes should be determined mainly by PSI. It was shown earlier that oligomeric (trimeric) and monomeric PSI complexes significantly differed in the region of Qy transition of Chl; ~.l xi 735(h1760 with a half-bandwidth of 32-34 nm is only present in the trimer, while nonfluorescent Chlvll with a half-bandwith of 14 nm is found both in the trimer and in the monomer [9]. However, the comparison of CD (Fig.…”

Section: Resultsmentioning

confidence: 82%

“…and Ph. laminosum [a~ 7,9]. PSI oligomers found electrophoretically in a number of cyanobacteria [2,3,13,14] are likely to be trimers as well.…”

Section: Discussionmentioning

confidence: 99%

“…Cells of the cyanobacterium Spirulina platensis were grown and the membranes were prepared as described in [9,10]. After Triton X-100 treatment (detergent:Chl = 20 mg/mg), nonsolubilized membranes were removed by centrifugation at 50,000 x g for 40 min at 4°C.…”

Section: Methodsmentioning

confidence: 99%

“…[11]. This is also necessary for studying the role of the trimer in energy conversion in PSI reaction center of cyanobacteria by monitoring the fluorescence yield at 760 nm depending on the redox state of P700 [9,10]. This paper gives the evidence that trimeric forms of PSI complexes preexist and predominate in membranes of the mesophilic cyanobacterium Spirulina; the structure of the trimer is identical to that of the trimeric forms of PSI complexes isolated from thermophilic cyanobacteria [4][5][6][7].…”

Section: Introductionmentioning

confidence: 95%

“…[4,5]; the yield of oligomeric PSI complexes (probably trimers) increased in the course of isolation as a result of chemical cross-linking of proteins before solubilization of cyanobacterial membranes [8]. Preexistence of an oligomeric PSI in Spirulina membranes was also suggested by the fact that the oligomeric PSI fraction contained a special Chl 760 (Ch1735) whose fluorescence yield depended on the redox state of P700 [9,10].…”

Section: Introductionmentioning

confidence: 99%

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Trimeric forms of the photosystem I reaction center complex pre‐exist in the membranes of the cyanobacterium Spirulina platensis

et al. 1993

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Oligomeric and monomeric forms of chlorophyll-protein complexes of photosystem I (PSI) have been isolated from the mesophilic cyanobacterium Spirulina [(1992) FEBS Lett. 309, 340-342]. Electron microscopic analysis of the complexes showed that the oligomeric form is a trimer of the shape and dimensions similar to those of the trimer from thermophilic cyanobacteria. The chlorophyl ratio in the isolated trimer and monomer was found to be 7:3. The trimeric form of PSI complex in contrast to the monomeric one contains the chlorophyll emitting at 760 nm (77K), which is also found in Spirulina membranes and therefore could be used as an intrinsic probe for the trimeric complex. The 77K circular dichroism spectrum of the trimeric form is much more similar to that of Spirulina membranes than the spectrum of the monomer. Thus, the trimeric PSI complexes exist and dominate in the Spirulina membranes.

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Section: Resultsmentioning

confidence: 82%

“…and Ph. laminosum [a~ 7,9]. PSI oligomers found electrophoretically in a number of cyanobacteria [2,3,13,14] are likely to be trimers as well.…”

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%