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At least 883 records · Page 49Linked to original sources
PubMed1984

Pentane formation during the anaerobic reactions of reticulocyte lipoxygenase. Comparison with lipoxygenases from soybeans and green pea seeds.

The lipoxygenases from reticulocytes, soybeans and green pea seeds produce pentane in an anaerobic assay containing 13Ls-hydroperoxy-9-cis, 11-trans-octadecadienoic acid and 9,12-all-cis-octadecadienoic acid. The presence of oxygen strongly inhibits pentane formation by the three enzymes. Relative to the lipoxygenase activity with linoleic acid as substrate, soybean lipoxygenase is 4-times as effective in pentane formation as the lipoxygenases from reticulocytes or green pea seeds. Pentane formation by the reticulocyte lipoxygenase is completely inhibited by lipoxygenase inhibitors (5,8,11,14-eicosatetraynoic acid, 3-t-butyl-4-hydroxyanisol) but only partially by radical scavengers which do not influence the oxygenase activity (2,6-di-t-butyl-4-hydroxytoluene). From the temperature dependence below 20 degrees C an activation energy of the pentane production by the reticulocyte lipoxygenase of about 28 kJ/mol was calculated, which is somewhat higher than that for the oxygenase activity. During the anaerobic reaction of both reticulocyte and soybean lipoxygenase C18-oxodienes, C13-oxodienes, linoleic acid dimers and a polar compound proposed to be epoxy-hydroxyoctadecenoic acid are produced in a similar pattern. Reticulocyte lipoxygenase produces pentane with submitochondrial particles only under anaerobic conditions after an aerobic preincubation. During the incubation of intact reticulocytes with the calcium ionophore A23187 or arachidonic acid, pentane is released. Preincubation of the cells with lipoxygenase inhibitors completely abolishes the pentane formation. Erythrocytes do not form any pentane under the same experimental conditions.

Anaerobiosis↗
PubMed1976

Protein synthesis in chloroplasts. VII. Initiation of protein synthesis in isolated intact pea chloroplasts.

Isolated intact pea chloroplasts use light energy to synthesise N-formayl [35S]-methionylpuromycin when incubated with L-[35S]methionine and puromycin. Control experiments establish that this synthesis occurs on chloroplast ribosomes, and not on contaminating mitochondrial or bacterial ribosomes. The amount of N-formylmethionylpuromycin formed suggests that each messenger RNA that is being translated in vitro undergoes initiation at least twice. We conclude that isolated, intact pea chloroplasts carry out the initiation of protein synthesis, as well as the elongation and termination of polypeptide chains.

Binding Sites↗
PubMed1979

Purification and subunit structure of RNA polymerase II from the pea.

DNA-dependent RNA polymerase II (EC 2.7.7.6) from pea seedlings (Pisum sativum var. Alaska) has been purified to homogeneity, as judged by native polyacrylamide electrophoresis. The procedure includes polyethyleneimine precipitation and elution, ammonium sulfate precipitation, DEAE-Sephadex chromatography, phosphocellulose chromatography, and heparin-Sepharose chromatography. The enzyme purified almost to homogeneity has a specific activity of 200 nmol/mg per 15 min at 30 degrees C with denatured calf thymus DNA as template. The enzyme activity is 50% inhibited in the presence of 0.05 migrograms/ml of alpha-amanitin. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate indicates that pea RNA polymerase II is composed of eight subunits with molecular weights and molar ratios (in parentheses) of 170 000 (0.9), 140 000 (1.0), 43 000 (1.5), 26 000 (2.0), 22 500 (1.2), 21 500 (0.6), 18 500 (1.6) and 17 500 (2.3). The structure is closely similar to that of cauliflower RNA polymerase II.

DNA-Directed RNA Polymerases↗
PubMed1978

The complete amino acid sequence of the alpha-subunit of pea lectin, Pisum sativum.

The complete primary structure of the alpha-subunit of the lectin from the pea (Pisum sativum) has been determined using a combination of tryptic and staphylococcal protease digestion, purification using Sephadex gel filtration and high-voltage electrophoresis followed by either manual or automated Edman degradation. The molecular weight of the alpha-subunit from sequence data and gel filtration in guanidine-HCl is close to 5800, which is lower than that determined by sedimentation equilibrium techniques. The sequence reveals considerable homology to concanavalin A and near identity to the alpha-subunit of the lentil lectin (Lens culenaris). As in the case of the lentil alpha-subunit, the alpha-methyl glucose binding site(s) are not present in this region, nor are the S1 and S2 metal ion binding sites as judged by homology consideration, though the residues for the S3 lanthanide binding (Glu 87 and Asp 136) are conserved from the available data on the alpha- and beta-subunits. Preliminary metal exchange experimens on the intact pea lectin indicate some differnces in the metal exchange properties of this lectin compared to concanavalin A, and therefore possible ligand variations in this region of the beta-subunit.

Amino Acid Sequence↗
PubMed1981

Purification of multiple pea ferredoxins by chromatography at high ionic strength on unsubstituted Sepharose 4B.

At high concentrations of ammonium sulfate (3--4 M) pea ferredoxin (which is soluble under these conditions) can be adsorbed to Sepharose 4B, either by column chromatography or by batchwise treatment. A reverse (3 M to 1 M) ammonium sulfate gradient results in the elution of three peaks of ferredoxin. The spectral ratio A420/A280 of 0.47--0.54 indicates that each peak of ferredoxin is highly purified by this single step. A further gel filtration removes residual high molecular weight contaminants from the ferredoxin. The spectrum of the purified pea ferredoxin is typical of other plant ferredoxins in having absorbance peaks at 276 nm, 330 nm, 422 nm and 465 nm. Other chromatographic matrices are capable of adsorbing ferredoxin. Sepharose and Sephacryl wee the best adsorbents while Sephadex and cellulose adsorbed ferredoxin less tenaciously. The polyacrylamide-based resins Biogel P-4 and P-200 did not adsorb ferredoxin at high ionic strength.

Adsorption↗
PubMed1990

The reaction specificities of the pea and a cyanobacterial thylakoid processing peptidase are similar but not identical.

The thylakoid processing peptidase from the cyanobacterium Phormidium laminosum has been extracted from thylakoid membranes by solubilization with Triton X-100. Its reaction specificity has been compared with the analogous pea peptidase by processing in vitro of radiolabelled wheat and P. laminosum thylakoid lumenal precursor polypeptides. The cyanobacterial polypeptide is processed to the mature size through an intermediate by the P. laminosum peptidase, but to a polypeptide that has a slightly greater apparent molecular weight than the intermediate by the pea peptidase. Both peptidases correctly process the wheat polypeptide. This suggests that the reaction specificities of the two peptidases are similar, but not identical.

Amino Acid Sequence↗
PubMed1991

A 55 kDa plasma membrane-associated polypeptide is involved in beta-1,3-glucan synthase activity in pea tissue.

By glycerol gradient centrifugation of a detergent-solubilized plasma membrane fraction from pea tissue, we find a polypeptide of 55 kDa that copurifies with beta-1,3-glucan synthase activity. An antiserum against this polypeptide adsorbs glucan synthase activity and the 55 kDa polypeptide from digitonin-solubilized plasma membrane. These results indicate that the 55 kDa polypeptide is involved in pea beta-1,3-glucan synthase activity.

Cell Fractionation↗
PubMed1992

Electrical potential dissipation induced by free fatty acids in pea stem mitochondria.

Linolenic, linoleic, oleic, palmitic and stearic acids (FFA) collapse the electrical potential of pea stem mitochondria in the absence or in the presence of 0.5 mM Mg2+. Higher concentrations of this cation (5 mM) lower the rate of dissipation caused by linoleic, oleic and palmitic acids, while abolishing that induced by stearic acid. Carboxyatractyloside and ADP do not reverse the FFA-induced collapse both in the presence or absence of Mg2+. EDTA, EGTA or BHT do not influence the dissipation caused by FFA that, in addition, is not linked to lipid peroxidation evaluated as malondialdehyde or conjugated diene formation. Only linolenic acid sustains a peroxidation which, however, appears to be caused by its own oxidation catalysed by lipoxygenases rather than by membrane lipoperoxidation induced by this free fatty acid. These results suggest that neither the ATP/ADP exchanger nor lipid peroxidation appear to be involved in FFA-induced uncoupling in pea stem mitochondria.

Cations, Divalent↗
PubMed1992

Processing of the chloroplast transit peptide of pea carbonic anhydrase in chloroplasts and in Escherichia coli. Identification of two cleavage sites.

The chloroplast transit peptide (cTP) of pea carbonic anhydrase was shown to be processed at two different sites, giving protein subunits of two sizes. The cleavage sites were identified and found to be localized immediately before and after a highly charged part, containing 8 acidic and 6 basic residues, of the cTP. Properties of pea carbonic anhydrase produced in Escherichia coli show that folding, oligomerization and catalytic activity do not depend on the presence of the acidic part or the rest of the cTP. The pattern of processing of the cTP in E. coli indicates that cleavage at site I is specific for a chloroplastic stromal peptidase and that cleavage at site I prevents processing at site II.

Amino Acid Sequence↗
PubMed1993

ATP-dependent protein synthesis in isolated pea chloroplasts. Evidence for accumulation of a translation intermediate of the D1 protein.

In the presence of externally added ATP, in the dark, isolated pea chloroplasts accumulate two proteins of molecular masses of about 22 and 24 kDa which precipitate with specific antibodies raised against the D1 protein. By chasing in the light, these proteins disappeared on the fluorogram concomitant with the appearance of the precursor- and mature-sized D1 proteins. Polysome analysis indicated that the 22-kDa component is associated with membrane-bound ribosomes and is thus ascribed to a translation intermediate of the D1 protein. On the other hand, the 24-kDa component could not be found in the polysome fraction under the experimental condition used, suggesting the possibility that this component is a degradation product of the D1 protein. The conclusion from this analysis is that the synthesis and/or stable accumulation of the D1 protein requires factor(s) caused by illumination, in addition to ATP, in isolated pea chloroplasts.

Adenosine Triphosphate↗
PubMed1995

Chloroplast import and sequential maturation of pea carbonic anhydrase: the roles of various parts of the transit peptide.

Chloroplast pea carbonic anhydrase is synthesised in the cytosol with an unusually long bipartite N-terminal extension of the mature sequence previously proposed to serve as a transit peptide. Studies of import into pea chloroplasts show that the N-terminal 69 amino acids of the previously proposed transit peptide is sufficient for translocation and localisation to the stroma, while the acidic C-terminal part does not seem to have any function in these processes. Processing of the in vitro imported precursors is shown to be at a new cleavage site located in the middle of the actual transit peptide. The results indicate that maturation occurs in more than one step. The time-course does not seem to be dependent on the age of the chloroplast but on the age of the translocated precursor.

Carbonic Anhydrases↗
PubMed1982

Cytomorphological and biochemical changes in dwarf pea shoots induced by gibberellic acid.

Treatment of 8-day-old pea plants for 15 and 24 hr with gibberellic acid resulted in: 1. 2-3 Fold increase of the cell length. 2. About 20% increase of the nuclei and nucleoli size in meristematic zone of plant shoots. 3. Increase of endomitotic and mitotic synthesis of DNA. 4. Increased ability of the cells to bind [3H]Actinomycin D. 5. Higher rate of RNA synthesis. 6. Increase of the fresh weight of apical parts of the green pea shoots. 7. These results indicated that gibberellic acid accelerates the growth and differentiation of plant cells.

Cell Nucleolus↗
PubMed1985

Rapid induction of specific mRNAs by auxin in pea epicotyl tissue.

DNA sequences complementary to three indoleacetic acid (IAA)-inducible mRNAs in pea epicotyl tissue were isolated by differential plaque filter hybridization of cDNA libraries constructed in the vector lambda gt10. Clone pIAA6 hybridized to an mRNA encoding the previously identified translational product polypeptide 6 (Mr 22,000), and clone pIAA4/5 hybridized to one or two mRNAs, encoding polypeptides 4 and 5 (Mr 23,000 and 25,000, respectively). The cDNA clones were subsequently used to characterize the hormonally mediated mRNA accumulation. The induction of the mRNAs was rapid, within 15 minutes of exposure to the IAA, and specific to auxins. Anaerobiosis, heat and cold stress did not induce the mRNAs. Other plant hormones, such as gibberellic acid, kinetin, abscisic acid and ethylene were also unable to cause or interfere with the IAA-induced mRNA accumulation. The hormonally regulated mRNAs were induced at least 50 to 100-fold above control levels after two hours of treatment with IAA and the accumulation was (1) independent of protein synthesis, (2) completely abolished by alpha-amanitin, (3) not due to polyadenylylation of pre-existing RNAs, and (4) independent of IAA and fusicoccin-induced H+ secretion. The IAA-induced mRNAs returned to control levels within three hours after removal of IAA, and the hormonally regulated genes were primarily expressed in the third and second internode of the seven-day-old etiolated pea seedling. The data indicate that IAA increases the amount of specific mRNAs rather than alters the translatability of pre-existing mRNAs. Auxin-induced H+ secretion appears not to have a potential role in mediating the induction and perhaps is a consequence of the enhanced biosynthetic activity induced by the hormone. The IAA-mediated mRNA induction is the fastest known for any plant growth regulator and may represent a primary hormonal response to auxin.

Amanitins↗
PubMed1986

Crystallization and preliminary X-ray diffraction studies of a pea lectin-methyl 3,6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside complex.

The seed lectin isolated from garden peas (Pisum sativum) has been co-crystallized with methyl 3,6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside in the orthorhombic space group P2(1)2(1)2(1) with unit cell dimensions a = 64.3 A, b = 73.4 A and C = 108.5 A. The asymmetric unit contains one pea lectin dimer (alpha 2 beta 2). The crystals are suitable for high-resolution structure analysis.

Crystallization↗
PubMed1987

A gene cluster in the spinach and pea chloroplast genomes encoding one CF1 and three CF0 subunits of the H+-ATP synthase complex and the ribosomal protein S2.

The regions of the spinach and pea chloroplast genomes containing the ATP synthase genes atpA, atpF and atpH have been sequenced. The encoded proteins, CF1 alpha, CF0I and CF0III, are well conserved between spinach and pea, and analogous to the alpha, b and c subunits of the Escherichia coli ATP synthase complex. The atpF gene is split by a single intron, and the exon/intron boundaries have been defined by isolating and sequencing a partial cDNA clone. Two other genes, designated atpI and rps2, located upstream from atpH, have also been sequenced. They encode a 27,000 Mr hydrophobic protein analogous to the F0a subunit of E. coli ATP synthase and a basic protein analogous to the S2 protein of the E. coli 30 S ribosomal subunit. Transcriptional analysis by electron microscopy of RNA-DNA hybrids, Northern blotting and primer extension experiments shows that these genes are transcribed and processed into a complex set of transcripts, with 5' ends mapping upstream from the rps2, atpI and atpH genes.

Amino Acid Sequence↗
PubMed1992

Detection of pea seedborne mosaic potyvirus by sequence specific enzymatic amplification.

The polymerase chain reaction (PCR) was used to detect pea seedborne mosaic potyvirus (PSbMV) pathotype P1 RNA after reverse transcription of total nucleic acid preparations from pea (Pisum sativum) tissues. Tissues assayed for PSbMV included leaves, roots, petals, seed parts, and pollen. Three oligonucleotide primers in appropriate combination yielded two products of the predicted size: 730 and 1200 bp. The described methodology allows for rapid pathotype-specific PSbMV detection with utmost sensitivity and wide applicability.

Base Sequence↗
PubMed1991

Isolation, characterization and partial amino acid sequence of a chloroplast-localized porphobilinogen deaminase from pea (Pisum sativum L.).

Porphobilinogen deaminase catalyzes the condensation of four porphobilinogen monopyrrole units into hydroxymethylbilane, a linear tetrapyrrole necessary for the formation of chlorophyll and heme in higher plant cells. We report the purification to homogeneity of a chloroplast-localized form of the enzyme from pea (Pisum sativum L.) by a novel purification scheme involving dye-ligand affinity chromatography. The purified chloroplast porphobilinogen deaminase consists of a single polypeptide with a relative molecular mass of 36-45 kDa as determined by size-exclusion chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis. The isoelectric point of the protein is acidic. The activity of the enzyme shows different levels of sensitivity to divalent cations and is most sensitive to FE2+. The amino terminus of pea enzyme has been obtained by microsequencing and determined to bear little similarity to the amino acid sequences of porphobilinogen deaminases purified from other organisms. Polyclonal antisera elicited against the purified protein has been used to examine the abundance and cellular distribution of the enzyme.

Amino Acid Sequence↗
PubMed1987

Glycosyltransfer by pea membranes from sugar nucleotides to added prenyl phosphates.

Pea membranes supplied with GDP-[14C]mannose, UDP-N-[14C]acetylglucosamine or UDP-[14C]glucose catalyze the transfer of 14C-labeled sugars or sugar phosphates to endogenous lipid acceptors as well as to exogenously added dolichyl phosphates. Fully unsaturated polyprenyl phosphates were not used as effective acceptors by this system. Mannosyl-P-dolichol was formed most rapidly in the presence of long-chained dolichyl-P while mannosyl-PP-, glucosyl-PP- and GlcNAc-PP-dolichol were preferentially formed from relatively short-chained dolichyl phosphate acceptors. Glucosyl-PP- and mannosyl-PP-dolichol accumulated in the preparation without further metabolism, but GlcNAc-PP-dolichol was lengthened by addition of a second GlcNAc plus several [14C]mannose units to form an oligosaccharide fraction susceptible to the action of endoglycosidase H. This lipid-linked oligosaccharide could then be glycosylated in the presence of UDP-[14C]glucose to form a longer oligosaccharide. It is concluded that levels of endogenous dolichyl phosphates in pea membranes are rate-limiting for several of the key glycosyltransferases required for oligosaccharide assembly.

Carbohydrate Metabolism↗