Ribulose 1,5-bisphosphate carboxylase and polyhedral bodies of Chlorogloeopsis fritschii |
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Authors: | T Lanaras G A Codd |
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Institution: | (1) Department of Biological Sciences, The University, DD1 4HN Dundee, U.K. |
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Abstract: | Ribulose 1,5-bisphosphate (RuBP) carboxylase (EC 4.1.1.39) activity was approximately equally distributed between supernatant and pellet fractions produced by differential centrifugation of disrupted cells of Chlorogloeopsis fritschii. Low ionic strength buffer favoured the recovery of particulate RuBP carboxylase. Density gradient centrifugation of resuspended cell-free particulate material produced a single band of RuBP carboxylase activity, which was associated with the polyhedral body fraction, rather than with the thylakoids or other observable particles. Isolated polyhedral body stability was improved by density gradient centrifugation through gradients of Percoll plus sucrose in buffer, which yielded apparently intact polyhedral bodies. These were 100 to 150 nm in diameter and contained ring-shaped, 12 nm diameter particles. It is inferred that the C. fritschii polyhedral bodies are carboxysomes. Sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis of SDS-dissociated polyhedral bodies revealed 8 major polypeptides. The most abundant, with molecular weights of 52,000 and 13,000, correspond with the large and small subunits, respectively, of RuBP carboxylase.Abbreviations RuBP
ribulose 1,5-bisphosphate
- Ru5P
ribulose 5-phosphate
- SDS
sodium dodecyl sulphate
- PAGE
polyacrylamide gel electrophoresis
- EDTA
ethylenediamine tetraacetic acid
- Tris
tris (hydroxymethyl) methylamine
- IB
isolation buffer
- TCA
trichloroacetic acid |
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Keywords: | Carboxysomes Chlorogloeopsis Cyanobacteria Polyhedral bodies Ribulose bisphosphate carboxylase |
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