Ribulose-l,5-bisphosphate

Knight, S., Andersson, I., Branden, C.-I. Crystallographic analysis of ribulose-l,5-bisphosphate carboxylase from spinach at 2.4 A resolution. Subunit interactions and active site. /. Mol. Biol. 215 113-160,... 

The addition of COg to ribulose-l,5-bisphosphate results in the formation of an enzyme-bound intermediate, 2-carboxy,3-keto-arabinitol (Figure 22.24). This intermediate arises when COg adds to the enediol intermediate gener-... 

As indicated, ribulose bisphosphate carboxylase/oxygenase catalyzes an alternative reaction in which Og replaces COg as the substrate added to RuBP (Figure 22.29a). The ribulose-l,5-bisphosphate oxygenase rezLCtion diminishes plant... 

Write a balanced equation for the synthesis of a glucose molecule from ribulose-l,5-bisphosphate and COg that involves the first three reactions of the Calvin cycle and subsequent conversion of the two glyceraldehyde-3-P molecules into glucose. 

Three-dimensional structure of ribulose-l,5-bisphosphate carboxylase/oxygenase from Rhodospirillum rubrum at 2.9 A resolution. EMBO J. 5, 3409-3415. 

Some of the many differences include the involvement of erythrose-4-phosphate and dihydroxyacetone phosphate in the production of sedoheptulose-1,7-bisphosphate, phosphorylation of ribulose-5-phos-phate to ribulose-l,5-bisphosphate, the addition of C02 to ribulose-l,5-bisphosphate, and the production of two glyceraldehyde-3-phosphates. 

DeRocher, E.J., Michalowski, C.B. Bohnert, H.J. (1991). cDNA sequences for transcripts of the ribulose-l,5-bisphosphate carbox-ylase/oxygenase small subunit gene family of Mesembryanthemum crystallinum. Plant Physiology 95, 976-8. 

Oxidation of ribulose-l,5-bisphosphate by Rubisco produces a 3-carbon compound, 3-phosphoglycerate, and a 2-carbon compound, phosphoglycolate. Because carbon is oxidized, the process is termed photorespiration. 

Fmax at light saturation and at the optimal temperature for photosynthesis varies with plant species but is usually from 2 to 10 mol m-3 s-1. We can also estimate Vmax from measurements of the maximum rates of CO2 fixation by isolated chloroplasts. These maximum rates—which are sustained for short periods and are for optimal conditions—can be 100 mmol of CO2 fixed (kg chlorophyll)-1 s-1 [360 pmol (mg chlorophyll)-1 hour-1 in another common unit], which is approximately 3 mol m-3 s-1 (1 kg chlorophyll is contained in about 0.035 m3 of chloroplasts in vivo). In vitro, the key enzyme for CO2 fixation, ribulose-l,5-bisphosphate carboxylase/oxygenase, can have rates equivalent to 200 mmol (kg chlorophyll)-1 s-1. The estimates of Vmax using isolated chloroplasts or enzymes usually are somewhat lower than its values determined for a leaf Measurements using leaves generally indicate that KqOz is 5 to 20 mmol m-3. For instance, Kcch can be 9 mmol m-3 at 25°C with a Q10 of 1.8 (Woodrow and Berry, 1988 Q10 is defined in Chapter 3, Section 3.3B). 

Figure 8-13. Schematic illustration of Rubisco (ribulose-l,5-bisphosphate carboxylase/oxygenase) acting as the branch point for photosynthesis and photorespiration. All three of the organelles involved, but only a few of the biochemical steps, are indicated. ( represents phosphate. Note that 3-phosphoglycerate and glycolate refer to the dissociated forms of 3-phosphoglyceric acid and glycolic acid, respectively.)...

Corredor, J. E., Wawrik, B., Paul, J. H., Tran, H., Kerkhof, L., Lopez, J. M., et al. (2004). Geochemical rate-RNA integrated study Ribulose-l,5-bisphosphate carboxylase/oxygenase gene transcription and photosynthetic capacity of planktonic photoautotrophs. Appl. Environ. Microbiol. 70, 5459—5468. 

Ekman, P., Lignel, A., and Pedersen, M. (1989). Localization of ribulose-l,5-bisphosphate carboxylase/ oxygenase in Gracilaria secundata (Rhodophyta) and its role as a nitrogen storage pool. Bot. Mar. 32, 527-534. 

Wyman, M. (1999). Diel rhythms in ribulose-l,5-bisphosphate carboxylase/oxygenase and glutamine synthetase gene expression in a natural population of marine picoplanktonic cyanobacteria Syne-chococais spp.). Appl. Environ. Microbiol. 65, 3651—3659. 

Beudeker R. F., Cannon G. C., Kuenen J. G., and Shively J. M. (1980) Relations between D-ribulose-l,5-bisphosphate carboxylase, carboxysomes, and C02-fixing capacity in the obligately chemolithotroph Thiobacillus neapolitanus grown under different limitations in the chemostat. Arch. Microbiol 124, 185-189. 

Ribosomal RNA Rous sarcoma virus Ribulose-l,5-bisphosphate Ribulose-5-phosphate Ribulose-1,5-bis phosphate... 

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