The mechanism of oxalate biosynthesis in higher plants: investigations with the stable isotopes 18 O and 13 C

1982 ◽  
Vol 216 (1202) ◽  
pp. 87-101 ◽  
Keyword(s):  
Spinacia Oleracea ◽  
Higher Plants ◽  
Direct Oxidation ◽  
Experimental Conditions ◽  
Carboxylase Activity ◽  
Oxalate Precursor ◽  
Organic C ◽  
Oxygenase Activity ◽  
C Value ◽  
Oxalate Synthesis

Substantial incorporation of 18 O 2 into photorespiratory carbon oxidation cycle intermediates in illuminated Spinacia oleracea leaves confirms that oxygenase activity of the enzyme ribulose biphosphate carboxylase–oxygenase is a major source of glycollate in illuminated leaves. No 18 O 2 incorporation into oxalate was detected in these experiments, although 13 C incorporation from 13 CO 2 shows that oxalate synthesis is occurring under the experimental conditions. This result tends to minimize the role of a direct oxidation of glyoxylate derived (via phosphoglycollate and glycollate) from ribulose biphosphate oxygenase activity in oxalate synthesis in Spinacia . Measurements of δ 13 C show (in confirmation of earlier reports) that oxalate from Spinacia is less depleted in 13 C than is bulk organic C in the plant; it is possible the phosphoenolpyruvate carboxylase is involved in the production of the oxalate precursor. Of the plants tested, Mercurialis and Pelargonium shared with Spinacia the high δ 13 C value, while Chenopodium (closely related to Spinacia ), Oxalis (more distantly related to Pelargonium ) and two members of the Polygonaceae had oxalate δ 13 C values close to the whole-leaf δ 13 C value, which suggests derivation of both oxalate C atoms from carboxylase activity of the enzyme ribulose biphosphate carboxylase–oxygenase.

Overexpression of a plant cysteine synthase gene and biosynthesis of a plant specific metabolite, β-(pyrazol-1-yl)-L-alanine, in Escherichia coli

1994 ◽  
Vol 72 (1) ◽  
pp. 188-192 ◽  
Author(s):  
Kazuki Saito ◽  
Reiko Kanda ◽  
Makoto Kurosawa ◽  
Isamu Murakoshi
Keyword(s):  
Escherichia Coli ◽  
Transcriptional Control ◽  
Spinacia Oleracea ◽  
Higher Plants ◽  
Total Soluble Protein ◽  
T7 Promoter ◽  
Cysteine Synthase ◽  
Mechanistic Investigation

Cysteine synthase (EC 4.2.99.8) in higher plants is responsible for biosynthesis of not only cysteine but also some nonprotein amino acids such as β-(pyrazol-1-yl)-L-alanine. The cDNA of a cysteine synthase from spinach (Spinacia oleracea) was inserted into pET8c (=pET3d) under the transcriptional control of strong T7 promoter to yield an overexpression vector pCEK1. The amount of the exogenous cysteine synthase was increased up to 40% of the total soluble protein of Escherichia coli transformed with pCEK1. β-(Pyrazol-1-yl)-L-alanine, a specific metabolite in plants of the Cucurbitaceae, was biosynthesized by overexpressed cysteine synthase from pyrazole in the presence of O-acetyl-L-serine and serine, in vitro and in vivo, respectively. The present study provides the system for mechanistic investigation of biosynthesis of cysteine and biogenetically related β-substituted alanines at molecular genetic level.

scholarly journals Electronic Structure of Tyrosyl D Radical of Photosystem II, as Revealed by 2D-Hyperfine Sublevel Correlation Spectroscopy

2021 ◽  
Vol 7 (9) ◽  
pp. 131
Author(s):  
Maria Chrysina ◽  
Georgia Zahariou ◽  
Nikolaos Ioannidis ◽  
Yiannis Sanakis ◽  
George Mitrikas
Keyword(s):  
Electronic Structure ◽  
Photosystem Ii ◽  
Water Oxidation ◽  
Spinacia Oleracea ◽  
Higher Plants ◽  
Correlation Spectroscopy ◽  
Oxygen Evolving Complex ◽  
Higher Plant ◽  
Proton Coupled Electron Transfer ◽  
S Oxidation

The biological water oxidation takes place in Photosystem II (PSII), a multi-subunit protein located in thylakoid membranes of higher plant chloroplasts and cyanobacteria. The catalytic site of PSII is a Mn4Ca cluster and is known as the oxygen evolving complex (OEC) of PSII. Two tyrosine residues D1-Tyr161 (YZ) and D2-Tyr160 (YD) are symmetrically placed in the two core subunits D1 and D2 and participate in proton coupled electron transfer reactions. YZ of PSII is near the OEC and mediates electron coupled proton transfer from Mn4Ca to the photooxidizable chlorophyll species P680+. YD does not directly interact with OEC, but is crucial for modulating the various S oxidation states of the OEC. In PSII from higher plants the environment of YD• radical has been extensively characterized only in spinach (Spinacia oleracea) Mn- depleted non functional PSII membranes. Here, we present a 2D-HYSCORE investigation in functional PSII of spinach to determine the electronic structure of YD• radical. The hyperfine couplings of the protons that interact with the YD• radical are determined and the relevant assignment is provided. A discussion on the similarities and differences between the present results and the results from studies performed in non functional PSII membranes from higher plants and PSII preparations from other organisms is given.

Effect of Antisera to RuBP-Carboxylase/Oxygenase of TV. tabacum and Spinacia oleracea on the Oxygenase-Function of the Enzyme

1990 ◽  
Vol 45 (7-8) ◽  
pp. 739-748
Author(s):  
M. Beuttenmüller ◽  
C. Nespoulous ◽  
A. Radunz ◽  
G. H. Schmid
Keyword(s):  
Spinacia Oleracea ◽  
Binding Capacity ◽  
Conformational State ◽  
Antibody Binding ◽  
Mutant Enzyme ◽  
Immunological Methods ◽  
Antigenic Determinants ◽  
Wild Type ◽  
Bisphosphate Carboxylase ◽  
Oxygenase Activity

Abstract In the present paper we demonstrate that the conformational state of the Afunctional enzyme ribulose-1,5-bisphosphate carboxylase oxygenase is different in the tobacco mulanl Susu when compared to the wild type tobacco or spinach. The conformational state of the tobacco mu- tant enzyme is characterized by the presence of a higher number of antigenic determinants ac- cessible to antibody binding. This seems to be correlated to a higher oxygenase activity in the mutant. The Afunctional enzyme ribulose-1,5-bisphosphate carboxylase oxygenase of the wild type tobacco Nicotiana tabacum var. John William’s Broadleaf, of the tobacco mutant Su.su and of spinach (Spinacia oleracea) was characterized by comparative immunological methods. Although the enzyme of the tobacco mutant appears identical to the enzyme of the wild type, when analyzed in immunodiffusion tests and immuno electrophoretical analyses, it exhibits a higher oxygenase activity. On the other hand the spinach enzyme exhibits only par- tial serological identity to the two tobacco enzymes. For the comparative studies pure IgG-fractions were prepared from the respective antisera. RuBP-carboxylasc oxygenase was used as a 70% purified enzyme preparation. Determination of the antibody binding capacity showed that the enzymes bind from the homologous antisera the highest amount of antibodies, which means that the antisera reflect the complementary picture of the enzyme structure. The enzyme molecules of N. tabacum var. JWB and of spinach bind 9 antibody molecules each. I lowevcr, the binding capacity of the tobacco mutant enzyme exhibiting the higher oxygenase activity is 30% higher. Measurement of the oxygenase function under the influence of the homologous as well as of the non-homologous antisera has led to the result that the oxygenase activity of all enzymes is inhibited. However, it is the degree of inhibition which differs. The antiserum to the mutant enzyme causes with the spinach as well as with the JWB-enzyme a higher degree of inhibition than that produced by the homologous antiserum. Therefore, a correlation between inhibitory effect brought about by this antiserum and the amount of antibodies bound does not exist. Whereas the enzyme of the tobacco wild type binds 20% less antibodies out of this antiserum its oxygenase activity is 60% more inhibited and the function of the spinach enzyme is 20% stronger inhibited although binding of antibodies from the antiserum to the tobacco enzyme is 50% lower. These observations permit the conclusion that the antiserum towards the mutant enzyme contains more antibodies with a higher binding affinity towards reactive regions of the oxy- genase function. This in turn means that the structure of this enzyme or its conformation must be different in comparison to the wild type enzyme.

Oxalate synthesis in leaves is associated with root uptake of nitrate and its assimilation in spinach (Spinacia oleracea L.) plants

2014 ◽  
Vol 95 (10) ◽  
pp. 2105-2116 ◽  
Author(s):  
Xiao Xia Liu ◽  
Kai Zhou ◽  
Yan Hu ◽  
Rong Jin ◽  
Ling Li Lu ◽  
...  
Keyword(s):  
Spinacia Oleracea ◽  
Root Uptake ◽  
Spinacia Oleracea L ◽  
Oxalate Synthesis

Interaction, functional relations and evolution of large and small subunits in Rubisco from Prokaryota and Eukaryota

1986 ◽  
Vol 313 (1162) ◽  
pp. 347-358 ◽  
Keyword(s):  
Green Algae ◽  
Higher Plants ◽  
Atmospheric Oxygen ◽  
Chloroplast Transformation ◽  
Chromatium Vinosum ◽  
Ribulose Bisphosphate Carboxylase ◽  
Carboxylase Activity ◽  
Bisphosphate Carboxylase ◽  
Unicellular Cyanobacterium ◽  
Functional Relations

In early biological evolution anoxygenic photosynthetic bacteria may have been established through the acquisition of ribulose bisphosphate carboxylase-oxygenase (Rubisco). The establishment of cyanobacteria may have followed and led to the production of atmospheric oxygen. It has been postulated that a unicellular cyanobacterium evolved to cyanelles which were evolutionary precursors of chloroplasts of both green and non-green algae. The latter probably diverged from ancestors of green algae as evidenced by the occurrence of large (L) and small (S) subunit genes for Rubisco in the chloroplast genome of the chromophytic algae Olisthodiscus luteus . In contrast, the gene for the S subunit was integrated into the nucleus in the evolution of green algae and higher plants. The evolutionary advantages of this integration are uncertain because the function of S subunits is unknown. Recently, two forms of Rubisco (L 8 and L 8 S 8 ) of almost equivalent carboxylase and oxygenase activity have been isolated from the photosynthetic bacterium Chromatium vinosum . This observation perpetuates the enigma of S subunit function. Current breakthroughs are imminent, however, in our understanding of the function of catalytic L subunits because of the application of deoxyoligonucleotide-directed mutagenesis. Especially interesting mutated Rubisco molecules may have either enhanced carboxylase activity or higher carboxylase: oxygenase ratios. Tests of expression, however, must await the insertion of modified genes into the nucleus and chloroplasts. Methodology to accomplish chloroplast transformation is as yet unavailable. Recently, we have obtained the first transformation of cyanobacteria by a colE1 plasmid. We regard this transformation as an appropriate model for chloroplast transformation.

scholarly journals Tailorable Aqueous-Media Synthesis of Heterogeneous Copper Nanoparticles Hybrids and Application in Selective Oxidation of Benzene

2019 ◽  
Author(s):  
Noelia Losada-Garcia ◽  
Alba Rodriguez-Otero ◽  
Jose M Palomo
Keyword(s):  
Hydrogen Peroxide ◽  
Selective Oxidation ◽  
Copper Nanoparticles ◽  
Room Temperature ◽  
Aqueous Media ◽  
Green Technology ◽  
Direct Oxidation ◽  
Experimental Conditions ◽  
Copper Species ◽  
Oxidation Of Benzene

Novel heterogeneous nanocatalysts has been synthesized in aqueous media at multimilligram scale for highly selective direct oxidation of benzene to phenol in aqueous media. The synthesis of a novel biohybrids containing copper nanoparticles (CuNPs) by an efficient and green technology have been described. The methodology involves the combination of an enzyme and a copper salt in aqueous media at room temperature. It was possible to control the copper species and nanoparticle size depending on the experimental conditions, e.g. pH, reducing step, amount of enzyme, obtaining novel heterogeneous nanobiohybrids containing exclusively Cu (0)NPs, Cu2O (Cu(i)) NPs or very crystalline Cu3(PO4)2 (Cu (ii)) NPs. Very small dispersed copper nanoparticles were formed in all cases (from 3 to 15 nm). These novel CuNPs biohybrids were evaluated as catalyst in the selective oxidation of benzene to phenol in water at 30ºC using hydrogen peroxide as oxidant, obtaining excellent yields and selectivity of phenol (>80% yield, >95% selectivity). <br>

Properties and Subcellular Localization of ʟ-Alanine: Aldehyde Aminotransferase: Concept of an Ubiquitous Plant Enzyme Involved in Secondary Metabolism

1981 ◽  
Vol 36 (7-8) ◽  
pp. 625-632 ◽  
Author(s):  
Coralie Wink ◽  
Thomas Hartmann
Keyword(s):  
Subcellular Localization ◽  
Secondary Metabolism ◽  
Spinacia Oleracea ◽  
Higher Plants ◽  
Ph Dependence ◽  
Metabolic Function ◽  
Aliphatic Aldehydes ◽  
Low Levels ◽  
Arum Maculatum ◽  
Plant Enzyme

Abstract L-Alanine: aldehyde aminotransferase occurs ubiquitously in higher plants. The enzyme catalyzes the reaction: L-alanine + monoaldehyde -> monoamine + pyruvate; it is responsible for the formation of aliphatic plant amines and involved in the biosynthesis of hemlock alkaloids as shown by Roberts. A continuous coupled photometric test was developed to determine the low activities of the transaminase. The enzyme from the "amine-free" plant Spinacia oleracea was purified 77-fold and separated from other aminotransferases. A comparison of the Spinacia enzyme with that isolated from spadix-appendices of the amine-producing Arum maculatum during anthesis revealed very similar characteristics in pH-dependence, ATm-values for alanine and aliphatic aldehydes, and inhibition by 2-oxoacids. In contrast to the Spinacia enzyme the Arum aminotransferase is rapidly inactivated in the absence of pyridoxal-5'-phosphate. The enzymes of S. oleracea, A. maculatum and Mercurialis perennis are localized in mitochondria, but not in chloroplasts or peroxisomes. The results are discussed in relation to the function of alanine: aldehyde aminotransferase in secondary metabolism. It is suggested that some enzymes may be expressed in plants at low levels, even in the absence of any metabolic function.

Are retinal and retinal-binding proteins involved in stomatal response to blue light?

2005 ◽  
Vol 32 (12) ◽  
pp. 1135 ◽  
Author(s):  
Fabio Paolicchi ◽  
Lara Lombardi ◽  
Nello Ceccarelli ◽  
Roberto Lorenzi
Keyword(s):  
Blue Light ◽  
Binding Proteins ◽  
Higher Plants ◽  
Guard Cells ◽  
Stomatal Response ◽  
Light Conditions ◽  
Experimental Conditions ◽  
Light Responses ◽  
Commelina Communis ◽  
Retinal Binding Proteins

Stomata respond to blue light and it is generally believed that the photoreceptor for this response is located inside the guard cells. Only a small number of blue light photoreceptors have been identified so far, namely cryptochromes and phototropins, and they show overlapping functions in regulating many different responses to light. The possibility that plants may possess other receptors regulating blue light responses under different light conditions cannot be excluded. In this paper we show the presence of two retinal-binding proteins in Commelina communis and we report the identification of retinal, a chromophore usually bound to the photoreceptor rhodopsin and previously identified in algae and other higher plants. We show that, under our experimental conditions, stomata open promptly when exposed to blue light and we demonstrated that this response is dependent on retinal. We hypothesise that rhodopsin-like retinal-binding proteins might be involved in stomatal response to blue light.

Hydroxylamine stimulates carboxylase activity and inhibits oxygenase activity of cyanobacterial RuBP carboxylase/oxygenase

Nature ◽  
1979 ◽  
Vol 279 (5713) ◽  
pp. 525-527 ◽  
Author(s):  
KEI-ICHIRO OKABE ◽  
GEOFFREY A. CODD ◽  
WILLIAM D. P. STEWART
Keyword(s):  
Rubp Carboxylase ◽  
Carboxylase Activity ◽  
Oxygenase Activity
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