Conversion of saccharopine to lysine in barley

Labelled saccharopine was synthesized and showed a low conversion to lysine in barley seedlings. The results indicate a role of saccharopine in either lysine biosynthesis or catabolism.     

Role of an indole alkaloid in the resistance of barley seedlings to aphids

The content of the simple indole alkaloid gramine in barley leaves decreased with age. Conversely, susceptibility to aphids increased in older plants. Population growth rate of the greenbug Schizaphis graminum correlated with gramine content of leaves of several barley cultivars. Gramine decreased rate of feeding, survival and reproductive index of aphids feeding on artificial diets at concentrations similar to those found in plant leaves. Thus, it is suggested that gramine plays a role in the resistance of barley seedlings to S. graminum. Benzyl alcohol, a previously reported insect resistance factor from barley, was absent from all barley cultivars analysed.     

漆酶催化苯甲醇氧化制备苯甲醛

以自制的高活性漆酶为催化剂,考察漆酶催化苯甲醇制备苯甲醛的工艺条件(底物浓度、介质体系、溶剂体系、氢受体、酶的用量、通氧方式等)对氧化反应的影响。结果发现:优化反应条件为以2,2,6,6-四甲基哌啶-1-氧基(TEMPO)为介质体系且TEMPO与苯甲醇的摩尔比为1∶4、60 mmol/L的丙酮为氢受体、漆酶比酶活80 U/mL、60mmol/L的苯甲醇,反应体系通O20.5 h后密闭反应36 h,苯甲醛的产率达98%。     

Effect of carnitine on greening barley leaves

Carnitine increases chlorophyll production in greening barley leaves. [Methyl-¹⁴C]carnitine fed to greening leaves was not utilized as a carbon sou     

Relationships between glycollate and formate metabolism in greening barley leaves

The activities of enzymes catalysing glycollate oxidation, formate production and folate-dependent formate utilization were examined in the primary leaves of Hordeum vulgare cv Galt. Seedlings were grown for 6 days in darkness and then transferred to continuous light (500 μinsteins/m² per sec) for up to 5 days. Cell-free extracts of the primary leaves contained glycollate oxidase (EC 1.1.3.1), 10-formyltetrahydrofolate synthetase (EC 6.3.4.3), 5, 10-methylenetetrahydrofolate dehydrogenase (EC 1.5.1.5) and ability to enzymically decarboxylate glyoxylate. These activities increased during greening and at the end of the light treatment were 70–450% higher than etiolated controls. Greened primary leaves also incorporated [¹⁴C]formate at rates that were three- to four-fold higher than shown by etiolated leaves. The specific activity of 10-formyltetrahydrofolate synthetase was decreased by 20–35% when the leaves were greened in the presence of 10 mM hydroxysulphonate. This inhibitor also reduced the incorporation of [¹⁴C]formate by up to 45%. A potential flow of carbon from glycollate to 10-formyltetrahydrofolate via glyoxylate and formate was suggested by the data.     

Cell specialization within the parenchymatous bundle sheath of barley

Abstract. Structural and physiological aspects of the parenchymatous bundle sheath (PBS) were studied in cultivars of Hordeum distichum L. The PBS of intermediate, lateral and midrib veins consisted of a single layer of cells closely appressed to the mestome sheath. These cells were large, vacuolate and approximately cylindrical in shape, extending parallel to the vein. Mean PBS cell volume was 4 × 10⁻⁵mm³ compared to 1.23 × 10⁻⁵mm³ for mesophyll cells. Transverse sections revealed three cell types within the PBS, cells with small chloroplasts (S-type), cells with large chloroplasts (L-type) and structural cells. The majority of cells were S-type, containing chloroplasts of approximately a third of the volume of mesophyll chloroplasts; they were able to reduce tetranitro blue-tetrazolium and synthesize starch. Structural cells interrupted the phloem and xylem are of the sheath in lateral veins and the midrib, whilst between one and four PBS cells within the phloem are of each vein type contained chloroplasts similar in volume and starch content to those of the mesophyll. Only these L-type cells contained noticeable starch grains at the end of an 8-h dark period, a further 4 h darkness being required for complete mobilization of starch. Starch deposition within S-type and structural cells was detectable after 4 h illumination but was only appreciable in leaves excised from the plant and illuminated for 9–12 h. The role of S-type PBS cells in assimilate transport is discussed in relation to these findings.     

Three alcohol dehydrogenase genes in wild and cultivated barley: Characterization of the products of variant alleles

Barley (Hordeum vulgare) and its wild progenitor (H. spontaneum) have three loci for alcohol dehydrogenase (EC 1.1.1.1; ADH). The Adh1 locus is constitutively expressed in seed tissues, whereas expression of the loci Adh2 and Adh3 requires anaerobic induction. The Adh3 gene is well expressed in aleurone and embryo tissues kept under N₂ for 2–3 days. Using N₂-treated embryos, a diverse collection of H. spontaneum was screened in starch gels for electrophoretic variants at the Adh3 locus. Four variants were found: two were conventional mobility variants (Adh3 S, Adh3 V); one was a null variant (Adh3 n); and the fourth (Adh3 I) variant lacked active homodimers and showed reduced heterodimer activity. The ³⁵S-labeled monomers induced under N₂ in the lines homozygous for Adh1, Adh2, or Adh3 variants were immunoprecipitated with antiserum raised against maize ADH. Fluorography after separation by SDS-PAGE and by urea-isoelectric focusing indicated that the Adh3 n allele was CRM- and that the Adh3 I gene product was smaller than normal. The Adh1 and Adh3 variants showed independent segregation.     

Assay of molybdenum cofactor of barley

Conditions for assay of molybdenum cofactor in barley shoot extracts in the presence of molybdate (25 mM N₂MoO₄) and the sulphydryl-group protector, reduced glutathione (5 mM) were optimized. Both total Mo-cofactor (assayed after heat-treatment of cell-free extracts) and ‘free’ Mo-cofactor (assayed in untreated cell-free extracts) were assayed. Compared to control plants grown in the absence of an exogenous nitrogen source total Mo-cofactor levels increased around 70 % when plants were grown for 4 days in the presence of either 15 mM KNO₃ or 15 mM NH₄NO₃. Growth in the presence of 15 mM (NH₄)₂SO₄ did not affect the Mo-cofactor level. Very similar results were seen when plants were transferred to these nitrogen sources for 24 hr after previous growth in the absence of an exogenous nitrogen source. In contrast ‘free’ Mo-cofactor levels of both KNO₃ and NH₄NO₃-treated plants were increased 2-3-fold over untreated controls. Growth in the presence of (NH₄)₂SO₄ did not affect the ‘free’ Mo-cofactor level.     

Effects of benzyl alcohol on phosphatidylcholine lamellar phase with different water contents

Effects of benzyl alcohol (BA) on the bilayer thickness d₁ and the fluidity of egg phosphatidylcholine (PC) lamellar phase with various water contents have been studied by X-ray diffraction and the proton spin-lattice relaxation rate. At lower water contents; BA causes d₁ to decrease and the rate of molecular motions to increase. By contrast, with increasing BA at excess water, d₁ remains nearly unchanged, though the rate of motions increases. Hydration experiment for egg phosphatidylcholine lamellae with BA at a 1:1 molar ratio shows that in the range from 15% to 30% water, d₁ decreases to the value of the fully hydrated sample without BA and is nearly constant above 30% water. The value at full hydration is suggested to be a lower limit of the bilayer thickness, the chain is in the unperturbed state. It is in an extended structure at lower water contents. This leads to the difference in the effect of BA on the bilayer thickness at different water contents.     

N-feruloylglycyl-l-phenylalanine: A sequence in barley proteins

N-Feruloylglycyl-l-phenylalanine was obtained from barley globulins by partial hydrolysis with 4 N HCl. It was isolated by means of preparative and ‘multiple elimination’ TLC (METC) and further identified by TLC comparison with a synthetic sample. Additional proof for its identity was obtained by UV, fluorescence and IR spectroscopy and by the action of carboxypeptidase A. The possible role of N-feruloylglycine as a starter in protein biosynthesis in the barley seed is discussed.     

Polyamines in barley seedlings

Polyamine levels in barley seedlings grown in the dark or in diurnal illumination have been determined, by direct dansylation, 3, 6 and 12 days after g     

Ent-kaurene,occurrence and metabolism in Hordeum distichon

Barley grains contain hydrocarbons, including a material indistinguishable from ent-kaurene by GLC, and which after appropriate chemical conversions contain material behaving like ent-kauran-16,17-diol, ent-kaurene norketone and ent-17-nor-kaurane on TLC and GLC. The presence of ent-kaurene was confirmed by conversion to ent-kauran-16-ol and, following formation of acetate-[³H], recrystallization to constant specific activity with unlabelled carrier. In the initial ca. 15 hr of germination, preceding the rise in endogenous gibberellins, the level of ent-kaurene falls. Exogenous ent-kaurene-[¹⁴C] was not metabolized by intact barley grains. ent-Kauran-16,17-epoxide was formed non-enzymically by boiled extracts. Unboiled homogenates also formed ent-kauran-17-ol and ent-kauran-16,17-diol. The diol appeared to be formed from the epoxide, but the ent-kauran-17-ol was not. No recognized gibberellin precursors were detected. Nevertheless, endogenous ent-kaurene may be the stored biosynthetic precursor of gibberellins in germinating barley grains.     

Characterisation of the endospermal trypsin inhibitor of barley

A trypsin inhibitor was isolated from grains of two row barley (cv. Proctor). The purified protein was identical with the corresponding inhibitor of a six row barley (cv. Pirkka); both proteins showed, a Pi of 7.4. The N-terminal amino acid was phenylalanine and an arginine residue was involved in the active site. Effects of substrate concentration showed that the inhibition was noncompetitive with a K_i of about 0.9 × 10^?7M. An enzyme-inhibitor complex was demonstrated by disc electrophoresis.     

Tissue localization of phytochrome in dark-grown barley leaves

Phytochrome was spectrophotometrically determined to be differentially concentrated among separated tissues of dark-grown, norflurazon-treated barley l     

Glycosides of 2-phenylethanol and benzyl alcohol in VitisVinifera grapes

β-Rutinosides and 6-O-α-l-arabinofuranosyl-β-d-glucopyranosides of 2-phenylethanol and benzyl alcohol have been found to co-occur with similar disaccharide glycosides of monoterpenes in Vitis vinifera vars. Muscat of Alexandria and Rhine Riesling. β-d-Glucopyranosides of these two alcohols were also identified in the fruit.     

Metabolism of ent-kaurenol-[17-14C], ent-kaurenal-[17-14C] and ent-kaurenoic acid-[17-14C] by germinating Hordeum distichon grains

Subcellular fractions from germinated barley embryos, chloroplast preparations and whole germinating barley grains are able to carry out the conversions ent-kaurenol → ent-kaurenal → ent-kaurenoic acid → ent-hydroxykaurenoic acid, the initial steps of the biosynthetic pathway to gibberellins. Whole grains, and chloroplasts to a slight extent, incorporate radioactivity from ent-kaurenol-[17-¹⁴C] and ent-kaurenoic acid-[17-¹⁴C] into materials with similar but distinct properties from the gibberellins GA₁, GA₃, GA₄ and GA₇.     

Properties of three sets of isoenzymes of alcohol dehydrogenase isolated from barley (Hordeum vulgare)

Three sets of isoenzymes of alcohol dehydrogenase were separated from root and shoot tissue of Hordeum vulgare by DEAE-cellulose chromatography. Set I showed only one band of ADH activity after polyacrylamide gel electrophoresis; Set II—two and Set III—three, making a total of six discernable bands. Only one set (I) was detected in the dry seed and one set (III) in the M9 (Adh-1-null) mutant available in tissue culture. The sets were found to have identical molecular weights (90 000), were all located in the cytoplasm but showed small differences in pH optima and substrate specificity. The affinity for ethanol (K_m value, mM) varied between Set I (27.5), Set II (7.2) and Set III (3.5), whilst the affinity for NADH varied five-fold between the three sets. A dimeric quaternary structure was inferred from the random reassociation of enzyme subunits after dissociation in high ionic strength buffer.     

Lysophosphatidylcholine biosynthesis in developing barley

Acetate-2-[¹⁴C] and choline-Me-[ ¹⁴C], absorbed through the stems of isolated barley heads, were used to label lysophosphatidylcholine (LPC) and phosphatidylcholine (PC) of the endosperm tissue. Labelling of LPC occurred in barley heads at almost all stages of development but was at a maximum when the fr. wt of the seeds had attained ca 60–70% of their maximum wt. In time-course experiments labelling of PC from each substrate reached a maximum after 50 hr and then declined. Label in LPC, however, continued to accumulate throughout 72 hr. Stimulation of labelling of LPC from choline-Me-[¹⁴C] by sucrose was observed. A bound form of LPC (starch lipid) and a free form were distinguished by differential solvent extraction.     

The biosynthesis of coumarylagmatine in barley seedlings

An enzyme present in extracts of the shoots of barley seedlings has been shown to synthesize coumarylagmatine from p-coumaryl-coenzyme A and [U-¹⁴C]agmatine.