This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Yokota, A. Articles by Canvin, D. T. Search for Related Content PubMed PubMed Citation Articles by Yokota, A. Articles by Canvin, D. T. Agricola Articles by Yokota, A. Articles by Canvin, D. T.

Articles

Ribulose Bisphosphate Carboxylase/Oxygenase Content Determined with [¹⁴C]Carboxypentitol Bisphosphate in Plants and Algae ¹

Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6

As is the case with spinach ribulose bisphosphate carboxylase/oxygenase (Rubisco), [¹⁴C]carboxyarabinitol bisphosphate (CABP) bound to purified Chlorella Rubisco with a molar ratio of unity to large subunit of the enzyme. The concentration of binding sites in extracts of photosynthetic organisms was determined by reacting the extracts with [¹⁴C]-carboxypentitol bisphosphate (CPBP) and precipitating the resultant Rubisco-[¹⁴C]CABP complex with a combination of polyethylene glycol-4000 and MgCl₂. Plots of the relationship between concentrations of [¹⁴C] CPBP in the reaction mixture and the precipitated [¹⁴C]CPBP gave a straight line and the concentration of binding sites were estimated by extrapolation to zero [¹⁴C]CPBP since the dissociation constant of CABP with Rubisco is 10^–11 molar. Spinach, pea, and soybean leaves contained 6.4 to 6.8 milligrams Rubisco per milligram chlorophyll, corresponding to 92 to 97 ribulose bisphosphate-binding sites per milligram chlorophyll. The Rubisco content of sunflower and wheat leaves was 5.3 to 5.5 milligrams per milligram chlorophyll. The concentrations in C₄ plants were not uniform and corn and Panicum miliaceum leaves contained 3 and 7 milligrams Rubisco per milligram chlorophyll. The Rubisco content of green algae was one-fifth to one-sixth that of C₃ plant leaves and was affected by the CO₂ concentration during growth. The content of Euglena and blue-green algae is also reported.

¹ Supported by the Natural Sciences and Engineering Research Council of Canada.

This article has been cited by other articles:

				Y. Yabuta, M. Tamoi, K. Yamamoto, K.-i. Tomizawa, A. Yokota, and S. Shigeoka Molecular Design of Photosynthesis-Elevated Chloroplasts for Mass Accumulation of a Foreign Protein Plant Cell Physiol., March 1, 2008; 49(3): 375 - 385. [Abstract] [Full Text] [PDF]

				J. C. Theobald, R. A.C. Mitchell, M. A.J. Parry, and D. W. Lawlor Estimating the Excess Investment in Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase in Leaves of Spring Wheat Grown under Elevated CO2 Plant Physiology, November 1, 1998; 118(3): 945 - 955. [Abstract] [Full Text]