Presence of molybdenum cofactor in seeds of wheat and barley

Molybdenum cofactor (Mo-co) was determined in seeds of wheat and barley by its ability to restore nitrate reductase (NR) activity in extracts of nitrate reductase-deficient mutants. Its activity was compared with that of wheat roots and leaves. Conditions for assay of Mo-co from different sources in the presence of molybdate and reduced glutathione (GSH) were optimised. The effect of heat-treatment of cell-free extracts from seeds, roots and leaves was also investigated. Mutant extracts of Neurospora crassa nit-1 and Nicotiana tabacum CnxA68, used as apoprotein source for in vitro complementation, were shown to give comparable results. The Mo-co activity, extracted from wheat and barley seeds, could be separated into two peaks by gel chromatography.     

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.     

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.     

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     

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     

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     

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.     

Comparison of cytoplasmic ribosomal proteins of gateway barley and its mutant

The proteins of the cytoplasmic ribosomes isolated from dry embryos of Gateway barley and its virescens mutant were compared by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). The monosomes of both the lines gave similar patterns with 60 basic proteins. Upon dissociation of the monosomes, for the mutant, the basic proteins of the large subunits migrated more slowly than those of the normal and lacked three proteins but had three additional spots. Also, the proteins of the small subunits differed. The mutant lacked three of the proteins present in the normal but had three additional spots. Therefore, the large and small subunits contained a total of 34 and 41 basic proteins, respectively, in both the lines. There were several spots with identical electrophoretic mobilities in the small and large subunits of these two lines.     

Proanthocyanidins of barley and sorghum; composition as a function of maturity of barley ears

Sorghum vulgare seeds contain a proanthocyanidin polymer consisting largely of 2,3-cis procyanidin units with M?_n, 2500. Hordeum vulgare ears contain low levels of proanthocyanidin oligomers containing 2–4 units, and composed largely of 2,3-trans procyanidin and prodelphinidin units with catechin as the terminal unit. The concentration of the oligomers in barley ears was virtually constant throughout the 33 day growth and ripening period.     

Purification of an nadh cytochrome c reductase from cell-free extracts of barley

The major cytochrome c reductase species present in cell-free extracts from 7-day old barley shoots was purified 848-fold by ammonium sulphate fraction     

Partial purification and properties of nuclease 1 from barley malt

A sugar-unspecific nuclease has been purified 260-fold from barley malt diastase. The enzyme, a glycoprotein of 37 000 MW, is highly active on single-stranded polynucleotides at pH 5–6. The nuclease is inhibited by several adenine nucleotides, and it binds weakly to NADP-agarose and ATP-agarose.     

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.     

Acidic metabolites of benzyl alcohol in greenbug resistant barley

(¹⁴C-Carbinol)benzyl alcohol taken up through the roots of greenbug (Schizaphis graminum) resistant barley is metabolized into a large number of radioactive compounds which have been separated by ion exchange chromatography. Two of these acidic metabolites have been identified as O-benzoyl-l-malic acid and N-benzoylaspartic acid; these identifications were confirmed by synthesis.     

Glycine metabolism in etiolated barley leaves on exposure to light

Of a large number of amino acids examined, changes in glycine were the only ones which were correlated with the ability of dark-grown barley leaves to synthesise protochlorophyllide, δ-aminolaevulinic acid and chlorophyll on exposure to light. A rapid depletion was found in endogenous glycine in barley leaves after day 7. Illumination of the leaves increased the rate of glycine depletion. Glycine concentrations were high throughout the young leaf. The top and middle leaf sections however, which had maximal chlorophyll synthesising potential exhibited the most pronounced decrease in glycine as the leaf aged. Using glycine-[¹⁴C] pulse techniques the half life of glycine in 7 and 14-day-old dark-grown leaves was 3.5 and 4.4 min respectively. Light treatment lengthened the half life to 6.9 and 12.1 min in 7 day and 14-day-old-leaves. Sustained illumination continued to decrease glycine turnover.     

Polymorphism of some glycosidases from barley

Barley grain extract displayed α-L-arabinosidase, β-fucosidase, β-galactosidase and β-glucosidase activities. Some of the glycosidases were separated from one another by Sephadex gel-filtration and CM-cellulose chromatography. The glycosidase types were more varied than reported by earlier workers. The multifunctional nature of some of the enzymes was demonstrated by inhibition studies, gel electrophoresis, pH and thermal stability studies.     

Phosphatidylethanolamine in wheat and barley leaves under water stress

Phosphatidylethanolamine could not be detected in the leaves of less drought-tolerant varieties of wheat (S-308) and barley (BG-25) when the plants wer     

Cytochromes of developing plastids of greening barley: Effects of inhibitors of haem synthesis

The properties of the cytochromes of etiolated barley plastids and 20 hr greened barley plastids were examined by potentiometric titration. In etiolate     

Polyamine oxidase from barley and oats

The pH optimum for the stability of the barley leaf polyamine oxidase is 4.8, which is also the pH optimum for its activity with spermine as substrate. Zonal centrifugation indicates that the enzyme is associated with a particle which is slightly more dense than chloroplasts, and the peak of activity corresponds with the peak of nucleic acid. Neither DNase nor RNase released the enzyme from the particles, despite the hydrolysis of more than 50% of the nucleic acid. The enzyme from the leaves of oat seedlings grown in the dark was purified 900-fold. Mg²⁺ and Ca²⁺ inhibited both barley and oat enzymes by ca 50% at 50 mM. The optimum pH for both spermine and spermidine oxidation by the oat enzyme was 6.5. The MW of the enzyme from both sources determined by gel chromatography was ca 85 000.     

The occurrence and photoregulation of flavonoids in barley plastids

Whole-leaf extracts of etiolated or light-grown barley shoots contain the C-glycosylflavones saponarin, lutonarin and lutonarin 3′-methyl ether. Plastids isolated by aqueous techniques contain only saponarin. Contamination experiments using foreign flavonoids indicate that saponarin recovered from plastids is not a contaminant from other cellular fractions. In response to brief red light treatment 24 hr before harvest, saponarin levels are approximately doubled in whole-shoot extracts, but increased about 3.5 fold in plastids. This photocontrolled increase is far-red reversible. Thus saponarin is selectively accumulated in barley plastids and this accumulation is controlled by phytochrome.     

In vitro stability of nitrate reductase from barley leaves

Barley seedling nitrate reductase was stabilized in vitro without the use of extraneous protein by optimizing the buffer components. The extraction buffer (NRT 8.5) consists of 0.25 M Tris-HCl, pH 8.5, 3 mM DTT, 5 μM FAD, 1 μ M sodium molybdate and 1 mM EDTA. This buffer stabilizes the extracted nitrate reductase at O° and 30°, whereas the addition of extraneous protein to standard extraction buffers stabilizes the enzyme only at 0°.