Ribuloses carboxylase

Figure 4.8 The active site in all a/p barrels is in a pocket formed by the loop regions that connect the carboxy ends of the p strands with the adjacent a helices, as shown schematically in (a), where only two such loops are shown, (b) A view from the top of the barrel of the active site of the enzyme RuBisCo (ribulose bisphosphate carboxylase), which is involved in CO2 fixation in plants. A substrate analog (red) binds across the barrel with the two phosphate groups, PI and P2, on opposite sides of the pocket. A number of charged side chains (blue) from different loops as welt as a Mg ion (yellow) form the substrate-binding site and provide catalytic groups. The structure of this 500 kD enzyme was determined to 2.4 A resolution in the laboratory of Carl Branden, in Uppsala, Sweden. (Adapted from an original drawing provided by Bo Furugren.)...

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,... 

Schneider, G., Lindqvist, Y., Lundqvlst, T. Crystallographic refinement and structure of ribulose-1,5-bisphosphate carboxylase from Rhodospirillum rubrum at 1.7 A resolution. J. Mol. Biol. 

H,COPO Ribulose-1,5-bis-phosphate (RuBP) carboxylase HCOH 1, H,C0P05 Two 3-Phospho- kinase 1,3-Blsphospho-glvcerate (BPG) dehydrogenase Glyceraldehydi 3-phosphate (G3P)... 

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... 

Van den Broek, G., Timko, M.P., Kausch, A.P., Cashmore, A.R., Van Montagu, M. Herrera-Estrella, L. (1985). Targeting of a foreign protein to chloroplasts by fusion to the transit peptide from the small subunit of ribulose 1,5-biphosphate carboxylase. Nature, 313, 358-63. 

Vierling, E. Key, J.L. (1985). Ribulose 1,5-bisphosphate carboxylase synthesis during heat shock. Plant Physiology, 78,155-62. 

Tapia, O., Andres, J. and Safont, V. S. Enzyme catalysis and transition structures in vacuo. Transition structures for the enolization, carboxylation and oxygenation reactions in ribulose- 1,5-bisphosphate carboxylase/oxygenase enzyme (Rubisco), J.Chem.Soc.Faraday Trans., 90 (1994), 2365-2374... 

Binding of C02 takes place in aqueous medium by the carboxylation reaction of ribulose-diphosphate (RuDP) with the formation of 3-phospho-glycerine acid (PGA) - table 5. Water molecule and radical C=0 at the distances of molecular interaction have quite similar values of PE-parameters for forming the general structural grouping of dimeric composite type. Total PE-parameter of water molecule and radical C=0 hearly equals PE-parameter of C02 and therefore the molecules of C02 and H20 join RuBP with the formation of two radicals COOH b PGA (table 5). In ferment RuDP- carboxylase, Mg atoms and 0" ions (5.4867 eV and 4.755 eV) play an active role, their PE-parameters similar to PE-parameter of radical COOH. 

RIBULOSE BISPHOSPHATE CARBOXYLASE LARGE CHAIN (EC 4.1.1.39). Anthoceros formosae. 

The virtual SWISS-PROT entries have a far-reaching effect on TrEMBL. For example, the virtual entry for the Rubisco (ribulose-bisphosphate carboxylase) large chain affects 3300 TrEMBL entries. Therefore a system has been developed to decompose these virtual entries into rules that are stored in a relational database with proper version control features. 

Bromo-l,4-dihydroxybutan-2-one 1,4-bisphosphate (31) has been prepared from the protected bromohydrin of cw-but-2-ene-l,4-diol.95 Nucleophiles rapidly displace bromide ion from (31), and the latter has been used as an affinity label for ribulose-bisphosphate carboxylase. In this case two sites are labelled in each enzyme molecule, the two molecules of (31) being linked to the enzyme by two different lysine residues.96... 

Cyclo(Pro-Tyr), also known as maculosin, is a phytotoxin produced by the fungus Altemaria alternata, and has been found to cause black necrotic lesions on the leaves of spotted knapweed. The mechanism underlying the phytotoxic action of cyclo(Pro-Tyr) may lie in its ability to inhibit ribulose-l,5-diphosphate carboxylase. ... 

Martin, J. S. and Martin, M. M. (1983). Tannin essays in ecological studies. Precipitation of ribulose-l,5-biphosphate carboxylase/oxygenase by tannic acid, quebracho, and oak foliage extracts. Journal of Chemical Ecology 9,285-294. 

Atmospheric CO2 first moves through the stomata, dissolves into leaf water and enters the outer layer of photosynthetic cells, the mesophyll cell. Mesophyll CO2 is directly converted by the enzyme ribulose biphosphate carboxylase/oxygenase ( Rubisco ) to a six carbon molecule that is then cleaved into two molecules of phosphoglycerate (PGA), each with three carbon atoms (plants using this photosynthetic pathway are therefore called C3 plants). Most PGA is recycled to make ribulose biphosphate, but some is used to make carbohydrates. Free exchange between external and mesophyll CO2 makes the carbon fixation process less efficient, which causes the observed large C-depletions of C3 plants. 

In this reaction, one molecule of ribulose-1,5-bisphosphate (metabolite 1) and one molecule of CO2 (metabolite 2) give rise to two molecules of 3-phosphoglycerate (metabolite 3). The enzyme responsible has the EC number 4.1.1.39. The annotated enzyme list shows that this refers to ribulose bisphosphate carboxylase ( rubisco for short). Rubisco belongs to enzyme class 4 (the lyases) and, within that group, to subclass 4.1 (the car-boxy-lyases). It contains copper as a cofactor ([Cu]). 

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