Regulation of Rubisco by inhibitors in the light |
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| Authors: | M. A. J. PARRY P. J. ANDRALOJC S. PARMAR A. J. KEYS D. HABASH M. J. PAUL R. ALRED W. P. QUICK J. C. SERVAITES |
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| Affiliation: | Biochemistry and Physiology Department, IACR-Rothamsted, Harpenden, Herts AL5 2JQ UK;Robert Hill Institute, University of Sheffield, PO Box 60 J, Sheffield S10 2UQ UK;Department of Biology, University of Dayton, 300 College Park, Dayton, OH 45469-2320, USA |
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| Abstract: | 2-carboxy-D-arabinitol-1-phosphate (CA1P) bound to Rubisco either in leaf extracts or after purification can be displaced by SO42? ions. Thus, treatment of leaf extracts with a buffer containing 200 mol m?3 SO42? displaces any bound CA1P and enables measurement of maximum car-boxylation potential. In tobacco leaves, the activity following treatment with SO4?2 ions (‘maximal activity’) is greater than the total Rubisco activity. The ratio of the two activities altered in a dynamic way with fluctuations in irradiance. Even in species which do not produce significant amounts of CA1P, the maximal activity greatly exceeded the total activity. Anion exchange separation of components in acid extracts confirmed the absence of CA1P in tobacco leaves harvested above an irradiance of 300 μmol quanta m?2 s?1, but the presence of another inhibitor of Rubisco. These results are consistent with the regulation of Rubisco activity by inhibitors other than CA1P which, like CA1P, can be displaced by SO42? ions. |
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| Keywords: | 2-carboxy-D-arabinitol-1-phosphate maximal activity regulation ribulose-1,5-bisphosphate ribulose-1,5-bisphosphate carboxylase/oxygenase total activity |
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