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  • 1
    Electronic Resource
    Electronic Resource
    Identification of peptides from the adenine binding domains of ATP and AMP in adenylate kinase: isolation of photoaffinity-labeled peptides by metal chelate chromatography (1992)
    s.l. : American Chemical Society
    Biochemistry 31 (1992), S. 4479-4487 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00133a014
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  • 2
    Electronic Resource
    Electronic Resource
    Photoaffinity labeling of the ATP binding domain of Rubisco activase and a separate domain involved in the activation of ribulose-1,5-bisphosphate carboxylase/oxygenase (1994)
    s.l. : American Chemical Society
    Biochemistry 33 (1994), S. 14879-14886 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00253a027
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  • 3
    Electronic Resource
    Electronic Resource
    RUBISCO: Structure, Regulatory Interactions, and Possibilities for a Better Enzyme (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Plant Physiology and Plant Molecular Biology 53 (2002), S. 449-475 
    Details
    ISSN: 1040-2519
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract Ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (Rubisco) catalyzes the first step in net photosynthetic CO2 assimilation and photorespiratory carbon oxidation. The enzyme is notoriously inefficient as a catalyst for the carboxylation of RuBP and is subject to competitive inhibition by O2, inactivation by loss of carbamylation, and dead-end inhibition by RuBP. These inadequacies make Rubisco rate limiting for photosynthesis and an obvious target for increasing agricultural productivity. Resolution of X-ray crystal structures and detailed analysis of divergent, mutant, and hybrid enzymes have increased our insight into the structure/function relationships of Rubisco. The interactions and associations relatively far from the Rubisco active site, including regulatory interactions with Rubisco activase, may present new approaches and strategies for understanding and ultimately improving this complex enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.arplant.53.100301.135233
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanism for deactivation of Rubisco under moderate heat stress (2004)
    Oxford, UK; Malden, USA : Munksgaard International Publishers
    Physiologia plantarum 122 (2004), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Photosynthesis is particularly sensitive to direct inhibition by heat stress. This inhibition is closely associated with the inactivation of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). To develop a more complete understanding of the mechanism of inactivation of Rubisco under moderate heat stress, various aspects of the process were examined both in vivo and in vitro. Experiments with isolated Rubisco revealed that the rate of synthesis of the catalytic misfire product, xylulose-1,5-bisphosphate, increased with temperature. Activated Rubisco, produced by reaction with activase at a control temperature of 25°C or by incubation with high CO2, deactivated when the temperature of the reaction exceeded temperatures that were equivalent to the optimum for activase adenosine triphosphatase (ATPase) activity. Measurements of the activation state of Rubisco in cotton and tobacco leaves showed that Rubisco inactivated within 7 s of imposing a heat stress. Thus, elevated temperature had an opposite effect on the two processes that ultimately determine the activation state of Rubisco, decreasing activase activity but stimulating the catalytic misfire reaction that inactivates Rubisco. These data support a mechanism for the inactivation of Rubisco at high temperature involving an inability of activase to overcome the inherently faster rates of Rubisco inactivation. That the net effect of elevated temperatures on Rubisco activation is similar both in vivo and under controlled conditions in vitro argues for a direct effect of temperature on the activation of Rubisco by activase and against the proposal that the deactivation of Rubisco under moderate heat stress is a secondary consequence of perturbations in the thylakoid membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.2004.00419.x
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  • 5
    Electronic Resource
    Electronic Resource
    Inhibition of photosynthesis by heat stress: the activation state of Rubisco as a limiting factor in photosynthesis (2004)
    Oxford, UK; Malden , USA : Munksgaard International Publishers
    Physiologia plantarum 120 (2004), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Although the catalytic activity of Rubisco increases with temperature, the low affinity of the enzyme for CO2 and its dual nature as an oxygenase limit the possible increase in net photosynthesis with temperature. For cotton, comparisons of measured rates of net photosynthesis with predicted rates that take into account limitations imposed by the kinetic properties of Rubisco indicate that direct inhibition of photosynthesis occurs at temperatures higher than about 30°C. Inhibition of photosynthesis by moderate heat stress (i.e. 30–42°C) is generally attributed to reduced rates of RuBP regeneration caused by disruption of electron transport activity, and specifically inactivation of the oxygen evolving enzymes of photosystem II. However, measurements of chlorophyll fluorescence and metabolite levels at air-levels of CO2 indicate that electron transport activity is not limiting at temperatures that inhibit CO2 fixation. Instead, recent evidence shows that inhibition of net photosynthesis correlates with a decrease in the activation state of Rubisco in both C3 and C4 plants and that this decrease in the amount of active Rubisco can fully account for the temperature response of net photosynthesis. Biochemically, the decrease in Rubisco activation can be attributed to: (1) more rapid de-activation of Rubisco caused by a faster rate of dead-end product formation; and (2) slower re-activation of Rubisco by activase. The net result is that as temperature increases activase becomes less effective in keeping Rubisco catalytically competent. In this opinionated review, we discuss how these processes limit photosynthetic performance under moderate heat stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0031-9317.2004.0173.x
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  • 6
    Electronic Resource
    Electronic Resource
    Regulation of Rubisco activity in vivo (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 77 (1989), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is not able to achieve and maintain adequate CO2 and Mg2+ activation under physiological conditions. Higher plants and green algae contain Rubisco activase, a soluble protein which not only facilitates Rubisco activation in situ but also regulates enzyme activity in response to irradiance and other factors. Regulation of Rubisco activity by modulation of activation state coordinates the rate of CO2 fixation with the rate of substrate regeneration. This regulation may be required to ensure that the levels of photosynthetic metabolites in the chloroplast are optimal for photosynthesis under a variety of environrmental conditions. Some plant species also appear to regulate Rubisco activity by synthesizing 2-carboxyarabinitol 1-phosphate, an inhibitor of Rubisco in the dark. This inhibitor may function primarily as a regulator of metabolite binding in the dark rather than as a modulator of Rubisco activity in the light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1989.tb05993.x
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  • 7
    Electronic Resource
    Electronic Resource
    Cloning and developmental expression of the sucrose-phosphate-synthase gene from spinach (1993)
    Springer
    Planta 190 (1993), S. 498-510 
    Details
    ISSN: 1432-2048
    Keywords: Gene expression (organ specificity) ; Leaf development ; Light (gene expression) ; Polymerase chain reaction ; Spinacia ; Sucrose-phosphate synthase (cDNA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A 561-base-pair (bp) polymerase-chain-reaction (PCR) product of sucrose-phosphate synthase (SPS) was amplified using degenerate oligonucleotide primers corresponding to tryptic peptides of SPS (EC 2.4.1.14) from spinach (Spinacia oleracea L). Crucial to the primer specificity and the synthesis of the 561-bp product was the use of primer pools in which the number of degenerate primer species was limited. A full-length cDNA was subsequently obtained by screening a cDNA bacteriophage library with the 561-bp product of SPS and 5′ PCR-RACE (Rapid Amplification of cDNA Ends). The 3530-bp cDNA of SPS encoded for a 1056-amino-acid polypeptide of predicted molecular mass of 117 kDa. The deduced amino-acid sequence of spinach SPS showed regions of strong homology with SPS from maize (A.C. Worrell et al., 1991, Plant Cell 3, 1121–1130); amino-acid identity was 54% over the entire protein. Western and Northern analyses of root, petiole and spinach leaf tissue showed that SPS was expressed in an organ-specific manner, being predominantly localized in the leaf. The accumulation of SPS protein and mRNA during leaf development coincided with the early rapid phase of leaf expansion and the apparent transition of the leaf from sink to source status. Levels of SPS mRNA and protein were reduced during the acclimation of leaves to low-irradiance conditions. Transfer of low-irradiance-adapted leaves to higher-irradiance conditions resulted in a gradual increase in SPS protein and mRNA. Diurnal changes in irradiance did not alter SPS protein or transcript levels, indicating that short-term regulation of SPS primarily involves a modulation of enzyme activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224789
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  • 8
    Electronic Resource
    Electronic Resource
    The Rubisco complex protein: A protein induced by fruit removal that forms a complex with ribulose-1,5-bisphosphate carboxylase/oxygenase (1994)
    Springer
    Planta 194 (1994), S. 110-116 
    Details
    ISSN: 1432-2048
    Keywords: Fruit removal and Rubisco ; Glycine (Rubisco and fruit removal) ; Jasmonic acid ; Ribulose-1,5-bisphosphate carboxylase/oxygenase ; Senescence (leaf) ; Storage protein (vegetative)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Continuous removal of fruits from soybean plants (Glycine max [L.] Merr.) causes a redistribution of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) from the soluble to the insoluble phase of leaf extracts. The extent of this redistribution is genotype-dependent. We previously reported that insoluble Rubisco occurs in a high-molecular-mass complex together with a protein composed of 30-kDa subunits (S.J. Crafts-Brander et al., Planta, 183, 300–306). In the present study, the Rubisco Complex Protein (RCP), was isolated from the Rubisco-RCP complex by gel-filtration chromatography in 4 M urea. Under these conditions, RCP migrated with an apparent molecular mass of 120 kDa, indicating that the protein maintains a tetrameric structure even in 4 M urea. Once freed of urea, purified RCP was soluble, but formed insoluble complexes with Rubisco from soybean, tobacco and spinach when RCP and Rubisco were incubated in a ratio of 1∶1 by weight. Purified Rubisco and RCP also associated into a high-molecular-mass complex when either component was in several-fold excess, but in this case the complex was soluble. Similarly, the amount of Rubisco sequestered as an insoluble Rubisco:RCP complex in leaf extracts of different soybean genotypes was related to the relative amounts of Rubisco and RCP present in the extracts. Thus, with both purified components and in leaf extracts, formation of an insoluble complex between Rubisco and RCP required a precise stoichiometry. Antibodies directed against purified RCP detected an accumulation of RCP in soybean leaves around the time of flowering. The RCP was also detected in petioles, stems, and pod walls of soybean, but not seeds. Fruit removal caused a marked increase in the amount of RCP in the leaves to levels as high as 15% of the total soluble protein. The accumulation of RCP in response to source:sink manipulations was similar to soybean vegetative storage proteins (VSPs). However, immunogold-localization showed that RCP was located in the cytosol of leaves, compartmentalized separate from both Rubisco and the VSPs. Thus, the physiological relevance of the specific association between RCP and Rubisco is obscure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00201041
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  • 9
    Electronic Resource
    Electronic Resource
    Fruit removal in soybean induces the formation of an insoluble form of ribulose-1,5-bisphosphate carboxylase/oxygenase in leaf extracts* (1991)
    Springer
    Planta 183 (1991), S. 300-306 
    Details
    ISSN: 1432-2048
    Keywords: Fruit removal and Rubisco ; Glycine (Rubisco and fruit removal) ; Leaf senescence ; Photosynthesis and fruit removal ; Ribulose-1,5-carboxylase/oxygenase ; Ribulose 5-phosphate kinase ; Senescence (leaf)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In some soybean (Glycine max (L.) Merr.) cultivars, fruit removal does not delay the apparent loss of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) activity and abundance or the decline in photosynthesis. Analysis of leaf extracts from defruited plants indicated a time-dependent increase in both Rubisco activity and abundance in a 30000 · g pellet fraction in cultivars which had been reported to lose all Rubisco protein from the supernatant fraction. Attempts to solubilize the pelleted Rubisco by increasing the buffer volume/tissue ratio or by adding alkylphenoxypolyethoxyethanol (Triton X-100), ethylenediaminetetraacetic acid (EDTA), or NaCl were unsuccessful. However, treatment of the pellets with denaturants such as 8 M urea or 5% (w/v) sodium dodecyl sulfate (SDS) did release Rubisco from the pellet. Redistribution of protein to the pellet fraction appeared to be specific for Rubisco since the amount of ribulose-5-phosphate kinase (EC 2.7.1.19) found in the pellet fraction of leaf extracts of control and defruited plants was small and constant over time. The loss of soluble Rubisco, and the concomitant increase in insoluble Rubisco, in response to fruit removal varied with genotype and was reproducible in both field and greenhouse environments. In addition, the effect was influenced by node position and light; lower and-or shaded leaves exhibited less Rubisco in the pellet fraction than leaves from the top of the plant that was fully exposed to sunlight. When isolated by sucrose-density-gradient centrifugation, the insoluble Rubisco was found to co-purify with a 30-kDa (kilodalton) polypeptide. These results indicate that alteration of the source/sink ratio by removing fruits results in the formation of an insoluble form of Rubisco in leaf extracts of soybean. Whether or not Rubisco exists as an insoluble complex with the 30-kDa polypeptide in intact leaves of defruited plants remains to be determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197802
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  • 10
    Electronic Resource
    Electronic Resource
    Photoaffinity labeling of ribulose-bisphosphate carboxylase/oxygenase with 8-azidoadenosine 5′-triphosphate (1990)
    Springer
    Planta 181 (1990), S. 287-295 
    Details
    ISSN: 1432-2048
    Keywords: Ribulose bisphosphate carboxylase/oxygenase ; Nucleotide binding ; Nicotiana (ribulose bisphosphate carboxylase/oxygenase) ; Photosynthesis (ribulose bisphosphate carboxylase/oxygenase)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photoaffinity labeling with [32P] 8-azidoadenosine 5′-triphosphate (8-N3ATP) was used to identify putative binding sites on tobacco (Nicotiana tabacum L. and N. rustica L.) leaf ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCase, EC 4.1.1.39). Incorporation of 32P was observed in polypeptides corresponding to both RuBPCase subunits when desalted leaf and chloroplast extracts, and purified RuBPCase were irradiated with ultraviolet light in the presence of [32P] 8-N3ATP. 32P-labeling was dependent upon ultraviolet irradiation and occurred with [32P] 8-N3ATP labeled in the α-position, indicating covalent incorporation of the photoprobe. Both [32P] 8-N3ATP and [32P] 8-N3GTP were incorporated to a similar extent into the 53-kilodalton (kDa) “large” subunit (LSu), but incorporation of [32P] 8-N3GTP into the 14-kDa “small” subunit (SSu) of RuBPCase was 〈5% of that measured with [32P] 8-N3ATP. Distinct binding sites for 8-N3ATP on the two subunits were indicated by different apparent K D values, 3 and 18 μM for the SSu and LSu, respectively, and differences in the response of photoaffinity labeling to Mg2+, anions and enzyme activation. Active-site-directed compounds, including the non-gaseous substrate ribulose 1,5-bisphosphate, the reaction intermediate analog 2-carboxyarabinitol-1,5-bisphosphate and several phosphorylated effectors afforded protection to the LSu site against photoincorporation but provided almost no protection to the SSu. These results indicate that 8-N3ATP binds to the active-site region of the LSu and a distinct site on the SSu of RuBPCase. Experiments conducted with intact pea (Pisum sativum L.) and tobacco chloroplasts showed that the SSu was not photolabeled with [32P] 8-N3ATP in organello or in undesalted chloroplast lysates but was photolabeled when lysates were ultrafiltered or desalted. These results indicate that 8-N3ATP binds to a site on the SSu that has physiological significance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195878
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