The inactivation of lactoperoxidase and the acyl phosphatase activity of oxidized glyceraldehyde-3-phosphate dehydrogenase by phenylhydrazine and phenyldiimide

The acyl phosphatase activity catalyzed by the sulfenic acid form of glyceraldehyde-3-phosphate dehydrogenase (GPD) is inactivated by phenylhydrazine, isopropylhydrazine, and phenyldiimide under anaerobic conditions. The hydrazines reactivate the dehydrogenase function of GPD and, therefore, reduce the sulfenic acid at the active site of the acyl phosphatase. Lactoperoxidase is also inactivated by phenylhydrazine, isopropylhydrazine, and phenyldiimide under anaerobic conditions. When lactoperoxidase is inactivated by an aerobic, aqueous solution of [¹⁴C] phenylhydrazine 1 mole of phenylhydrazine is covalently bound per 40,000 g of lactoperoxidase.     

Incorporation of [14C]Methanol and [14C]Bicarbonate by Hyphomicrobium sp. 53-49 under Various Growth Conditions: Aerobic,Denitrifying and Autotrophic

A study was made of the incorporation of methanol and bicarbonate into the cell constituents of denitrifying or aerobic methanol grown and autotrophic H₂–O₂–CO₂ grown Hyphomicrobium sp. 53-49. Cells were incubated with [¹⁴C]methanol or [¹⁴C]bicarbonate, and the distribution of the radioactivity in the nonvolatile constituents of ethanol extracts of cells was examined. When denitrifying grown cells were incubated with [¹⁴C]methanol, the major part of the radioactivity was fixed to serine as the first stable compound. Aerobic methanol grown cells also fixed [¹⁴C]methanol mainly to serine. These results suggest that methanol grown cells assimilate methanol by the serine pathway. When denitrifying or aerobic methanol grown cells were incubated with [¹⁴C]bicarbonate, malate was mainly observed as a nonvolatile compound in the initial period of the incubation. Autotrophic grown cells also fixed the major part of [¹⁴C]bicarbonate to malate. In this case, phosphoglyceric acid was found in the phosphorylated compounds area.     

Non-enzymatic formation of sulfenyl iodide by solubilized thyroid particulate protein with peroxidase activity

Thyroidal particulate protein with peroxidase activity has been studied to determined wetherr it could be induced to form a sulfenyl iodide, postulated as a reactive intermediate in the iodination of tyrosine. The protein was solubilized with digitonin and purified by tryptic digestion and filtration through Sephadex G-200. When supplemented with H₂O₂ it catalyzed the oxidation of guaiacol iodide or thiourea at 37°C. With iodide as substrate the product was an iodoprotein. In the absence of H₂O₂ the protein did not bind ¹³¹I^? or thio[¹⁴C] urea unless it first had been dialyzed against [³⁶Cl] chlorinated buffer. During dialysis a portion of the ³⁶Cl from the dialysis medium was bound by protein. Subsequent binding of iodide or thiourea was accompanied by loss of protein-bound ³⁶Cl.Addition of iodide to dialyzed protein at 4°C resulted in formation of a yellow compound with maximum absorbance at 355 nm. It was postulated to be a sulfenyl periodide on the basis of its absorption spectrum and its behavior with thio[¹⁴C] urea and 2-mercaptoethanol. The stability of the colored species was dependent on temperature and concentration of iodide. Disappearance of color as the solution was warmed was accompanied by formation of iodo-protein. Predialysis of the protein against p-chloromercuribenzoate, but not 2-mercaptoethanol or bisulfite, prevented the formation of the yellow proteiniodide species, indicating that a reactive sulfhydryl group was involved in the reaction. It was concluded that a particulate protein closely asscociated with thyroid peroxidase could be induced by non-enzymatic means to form a species which has properties consistent with those of a sulfenyl iodide. Further investigation will be required to determine whether the same protein-iodine species can be identified during the peroxidase-catalyzed oxidation of iodide.     

Sucrose uptake by sugar beet tap root tissue

Sucrose uptake by discs of mature sugar beet root tissue incubated in [¹⁴C]-sucrose exhibited nonsaturating kinetics over the concentration range of 1 to 500 millimolar. Uptake was inhibited by dinitrophenol, sodium cyanide, low O₂, and penetrating sulfhydryl inhibitors. ATPase inhibitors, sodium fluoride, and oligomycin reduced uptake by 20 and 40%, respectively. Uptake as asymmetrically labeled sucrose ([¹⁴C]glucose) occurred with approximately 80% retention of asymmetry, indicating a nonhydrolytic pathway. Uptake was against a concentration gradient and required metabolic energy.     

IN VITRO STUDIES ON THE INTERACTION OF BRAIN MONOAMINE OXIDASE WITH 5,6- AND 5,7-DIHYDROXYTRYPTAMINE12

[¹⁴C]5,6-Dihydroxytryptamine ([¹⁴C] 5,6-DHT) and [¹⁴C]5,7-dihydroxytryptamine ([¹⁴C]5,7-DHT) were deaminated to toluene-isoamylalcohol extractable products when incubated with homogenates of rat hypothalamus or pons-medulla oblongata. [¹⁴C]5,6-Dihydroxyindole acetic acid ([¹⁴C]5.6-DHIAA) and [¹⁴C]5,7-dihydroxyindole acetic acid ([¹⁴C]5,7-DHIAA) were detected as MAO metabolites by TLC besides non-identified components. The conversion of [¹⁴C]5,6-DHT and [¹⁴C]5,7-DHT obeyed, at least initially, Michaelis-Menten kinetics (K_m 5,7-DHT: 0.5 × 10^?3M; K_m 5,6-DHT: 1.25 × 10^?3M). Inhibition of the reaction by the MAO A inhibitor, clorgyline, resulted in a typical double sigmoidal inhibition curve indicating that both amines are metabolized by both types of MAO (A and B). In deprenyl inhibition studies, however, 5,7- and 5,6-DHT seemed to be preferred substrates of MAO A. Incubation of rat brain homogenates with [¹⁴C]5,6-DHT and [¹⁴C]5,7-DHT or with the MAO metabolites [¹⁴C]5,6-DHIAA and [¹⁴C]5,7-DHIAA caused a time-dependent break-down of the dihydroxylated indole compounds with subsequent binding of radioactivity to perchloric acid insoluble tissue components. 5,6-DHT inactivated MAO in rat brain homogenates parallel to its decomposition and extensive protein binding. The inactivation of MAO by 5,6-DHT and the extensive binding of radioactivity to protein were antagonized by dithiothreitol (DTT), glutathione (GSH) and L-ascorbic acid. Reduction of [O₂] in the incubation medium slightly attenuated the inactivation of MAO by 5,6-DHT. Catalase or superoxide dismutase failed to prevent MAO from being inactivated by 5,6-DHT. The results suggest that oxidation products of 5,6-DHT, e.g. its corresponding o-quinone, are involved in the inactivation of MAO in vitro and mainly responsible for the binding of radioactivity to brain proteins in vitro. Similar mechanisms may also be operative in the in vivo neurotoxicity of 5,6-DHT. The lack of inactivation of MAO by 5,7-DHT in vitro correlated with a low degree of radioactivity binding (from [¹⁴C]5,7-DHT) to homogenate protein pellets; the binding to proteins was barely influenced by GSH, cysteine, DTT and l -ascorbic acid. These latter findings do not provide a plausible explanation for the mechanism(s) involved in the well known in vivo neurotoxicity of 5,7-DHT.     

Enzymatic methods for the determination of L-serine concentration and L-[14C]serine specific radioactivity in blood plasma

Methods are desribed for the use of l-serine dehydratase purified from Clostridium acidiurici for the determination of l-serine concentration and l[¹⁴C]serine specific radioactivity in sheep plasma. A spectrophotometric assay using this enzyme accurately measured the concentration of l-serine in standard solutions and in a commercially available mixture of amino acids and related compounds. This assay was shown to be suitable for measurement of plasma l-serine concentrations in excess of 30 μm. The reverse isotope dilution method was used for plasma l-[¹⁴C]serine specific radioactivity measurements. Carrier l-serine was added to plasma and separated from neutral and anionic compounds using ion-exchange chromatography. The l-serine was then converted to pyruvate with l-serine dehydratase and this was purified as the phenylhydrazone derivative. After recrystallization, drying and weighing, the derivative was assayed for radioactivity. The accuracy of this method was verified by adding l-[U-¹⁴C]serine to plasma and comparing the experimentally determined l-[¹⁴C]serine specific radioactivity with the calculated value. The method yielded a value which was 98.6 ± 0.8% (5) of this calculated value.     

Synthesis of reserved polysaccharide from wax esters accumulated as the result of anaerobic energy generation in Euglena gracilis returned from anaerobic to aerobic conditions

• 1.1. Euglena gracilis SM-ZK (a non-photosynthetic mutant), cultured in Koren-Hutner medium, containing glucose, malate and glutamate as the main nutrients, were incubated anaerobiosis for 24 hr, and then returned to aerobic conditions. Wax esters, which were synthesized from paramylon (the reserved polysaccharide) for ATP generation under anaerobiosis (wax ester fermentation) were promptly degraded immediately after the cells were replenished with sufficient O₂. A large part (about 70%) of the decomposed wax esters were converted back to paramylon.
• 2.2. When cells were fed with [1–14C]acetate or [U-¹⁴C]acetate immediately after transfer from anaerobic to aerobic conditions, radioactivity incorporated into paramylon in the cells fed with [U-¹⁴C]acetate was about 1.5-times as high as that with [1-¹⁴C]acetate, proposing that glyoxylate cycle participates in the conversion from wax esters to paramylon.
• 3.3. Paramylon synthesis from [1-¹⁴C]acetate was considerably activated by anaerobic preincubation of cells for several hours.
• 4.4. Isocitrate lyase and malate synthase occurred in cells cultured in Koren-Hutner medium, but the activities were obviously lower than those in cells grown on ethanol. These enzymes were not induced by the anaerobic preincubation.

     

Determination of the specific radioactivity of 14C-labeled glutamic acid and glutamine

A new, simple, and accurate method for the sequential determination of the specific radioactivity of [1-¹⁴C]glutamic acid and [1-¹⁴C]glutamine is described. Using this method, radioactivity in H¹⁴CO₃^?, in [¹⁴C]glutamic acid, and in [¹⁴C]-glutamine can be readily determined on a single sample of blood plasma. Radioactivity is released as ¹⁴CO₂ in a stepwise fashion, trapped in the center wells, and counted in a liquid scintillation counter. The applicability of the method is discussed.     

Metabolism of surfactants sodium undecyltriethoxy sulphate and sodium dodecyltriethoxy sulphate in the rat

The metabolic fates of the synthetic surfactants, sodium [1-¹⁴C]undecyltriethoxy sulphate and sodium [1-¹⁴C]dodecyltriethoxy sulphate were studied in the rat. Both compounds were extensively metabolized regardless of the route of administration, oral, intraperitoneal or intravenous. Short-chain radioactive products were eliminated in the urine: the major metabolite of the dodecyl homologue in the urine was identified as ⁻O₂C¹⁴CH₂- (OC₂H₄)₃OSO₃⁻ by n.m.r. and g.l.c.–mass spectrometry, whereas the major metabolite of the undecyl homologue in the urine was tentatively identified as ⁻O₂CCH₂¹⁴CH₂- (OC₂H₄)₃OSO₃⁻. In contrast with experiments with the dodecyl derivative, when [1-¹⁴C]undecyltriethoxy sulphate was administered to rats, appreciable amounts of radioactivity were recovered as ¹⁴CO₂ in expired air. Whole-body radioautography implicated the liver as the major site of metabolism of both surfactants. The nature of the metabolic products establishes that both compounds are degraded by ω,β-oxidation. Cleavage of the ether linkage proximal to the sulphate moiety may account for the small amounts of ¹⁴CO₂ recovered in expired air after the administration of [1-¹⁴C]dodecyltriethoxy sulphate. It is suggested the substantial amounts of ¹⁴CO₂ recovered after [1-¹⁴C]-undecyltriethoxy sulphate administration originate from ⁻O₂¹⁴C(OC₂H₄)₃ OSO₃⁻, an unstable product of ω,β-oxidation. An n.m.r. spectrum of the metabolite identified as 2-(triethoxy sulphate)acetic acid and a mass spectrum of the trimethylsilyl derivative of the parent alcohol of that metabolite have been deposited as Supplementary Publication SUP50086 (5 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1978) 169, 5.     

Oxalate metabolism by tobacco leaf discs

The turnover rate of oxalate in leaf discs of Nicotiana tabacum, var Havana Seed, during photosynthesis was estimated to be 1 to 2 micromoles per gram fresh weight per hour. Radioactivity from the enzymic oxidation of [¹⁴C]oxalate rapidly appeared in neutral sugars (mainly sucrose), organic acids (mainly malate), and amino acids. Only 5% of the radioactivity was released to the atmosphere as ¹⁴CO₂, and no formate or formaldehyde could be detected. The metabolism of oxalate was not increased by raising the O₂ concentration from 1% to 21% to 60%, nor was the formation of [¹⁴C]oxalate from [2-¹⁴C]glyoxylate changed under the same conditions as was previously observed in vitro (Havir 1983 Plant Physiol 71: 874-878). While oxalate is not an inert end product of the glycolate pathway, it contributes little to the formation of photorespiratory CO₂.     

Intraprotoplasmic and wall-localised formation of arabinoxylan-bound diferulates and larger ferulate coupling-products in maize cell-suspension cultures

Maize (Zea mays L.) cell cultures incorporated radioactivity from [¹⁴C]cinnamate into hydroxycinnamoyl-CoA derivatives and then into polysaccharide-bound feruloyl residues. Within 5–20 min, the CoA pool had lost its ¹⁴C by turnover and little or no further incorporation into polysaccharides then occurred. The system was thus effectively a pulse–chase experiment. Kinetics of radiolabelling of diferulates (also known as dehydrodiferulates) varied with culture age. In young (1–3 d) cultures, polysaccharide-bound [¹⁴C]feruloyl- and [¹⁴C]diferuloyl residues were both detectable within 1 min of [¹⁴C]cinnamate feeding. Thus, feruloyl residues were dimerised <1 min after their attachment to polysaccharides. For at least the first 2.3 h after [¹⁴C]cinnamate feeding, polysaccharide-bound [¹⁴C]diferuloyl residues remained almost constant at ≈7% of the total polysaccharide-bound [¹⁴C]ferulate derivatives. Since feruloyl residues are attached to polysaccharides <1 min after the biosynthesis of the latter, and >10 min before secretion, the data show that extensive feruloyl coupling occurred intra-protoplasmically. Exogenous H₂O₂ (1 mM) caused little additional feruloyl coupling; therefore, wall-localised coupling may have been peroxidase-limited. In older (e.g. 4 d) cultures, less intraprotoplasmic coupling occurred: during the first 2.5 h, polysaccharide-bound [¹⁴C]diferuloyl residues were a steady 1.4% of the total polysaccharide-bound [¹⁴C]ferulate derivatives. In contrast to the situation in younger cultures, exogenous H₂O₂ induced a rapid 4- to 6-fold increase in all coupling products, indicating that coupling in the walls was H₂O₂-limited. In both 2- and 4-d-old cultures, polysaccharide-bound ¹⁴C-trimers and larger coupling products exceeded [¹⁴C]diferulates 3- to 4-fold, but followed similar kinetics. Thus, although all known dimers of ferulate can now be individually quantified, it appears to be trimers and larger products that make the major contribution to cross-linking of wall polysaccharides in cultured maize cells. We argue that feruloyl arabinoxylans that are cross-linked before and after secretion are likely to loosen and tighten the cell wall, respectively. The consequences for the control of cell expansion and for the response of cell walls to an oxidative burst are discussed. Received: 19 January 2000 / Accepted: 13 April 2000     

Purine and pyrimidine metabolism in cultured white spruce (Picea glauca) cells: Metabolic fate of 14C-labeled precursors and activity of key enzymes

In order to examine the biosynthesis, interconversion, and degradation of purine and pyrimidine nucleotides in white spruce cells, radiolabeled adenine, adenosine, inosine, uracil, uridine, and orotic acid were supplied exogenously to the cells and the overall metabolism of these compounds was monitored. [8‐¹⁴C]adenine and [8‐¹⁴C]adenosine were metabolized to adenylates and part of the adenylates were converted to guanylates and incorporated into both adenine and guanine bases of nucleic acids. A small amount of [8‐¹⁴C]inosine was converted into nucleotides and incorporated into both adenine and guanine bases of nucleic acids. High adenosine kinase and adenine phosphoribosyltransferase activities in the extract suggested that adenosine and adenine were converted to AMP by these enzymes. No adenosine nucleosidase activity was detected. Inosine was apparently converted to AMP by inosine kinase and/or a non‐specific nucleoside phosphotransferase. The radioactivity of [8‐¹⁴C]adenosine, [8‐¹⁴C]adenine, and [8‐¹⁴C]inosine was also detected in ureide, especially allantoic acid, and CO₂. Among these 3 precursors, the radioactivity from [8‐¹⁴C]inosine was predominantly incorporated into CO₂. These results suggest the operation of a conventional degradation pathway. Both [2‐¹⁴C]uracil and [2‐¹⁴C]uridine were converted to uridine nucleotides and incorporated into uracil and cytosine bases of nucleic acids. The salvage enzymes, uridine kinase and uracil phosphoribosyltransferase, were detected in white spruce extracts. [6‐¹⁴C]orotic acid, an intermediate of the de novo pyrimidine biosynthesis, was efficiently converted into uridine nucleotides and also incorporated into uracil and cytosine bases of nucleic acids. High activity of orotate phosphoribosyltransferase was observed in the extracts. A large proportion of radioactivity from [2‐¹⁴C]uracil was recovered as CO₂ and β‐ureidopropionate. Thus, a reductive pathway of uracil degradation is functional in these cells. Therefore, white spruce cells in culture demonstrate both the de novo and salvage pathways of purine and pyrimidine metabolism, as well as some degradation of the substrates into CO₂.     

Effect of pyridoxine deficiency on nucleic acid metabolism in the rat

1. The nucleic acid metabolism in the pyridoxine-deficient rat has been investigated through studies on the incorporation of radioactivity from various isotopically labelled compounds into liver and spleen DNA and RNA. 2. In pyridoxine deficiency, the incorporation of radioactivity from sodium [¹⁴C]formate was apparently increased. The magnitude of this effect on incorporation into liver RNA and DNA and spleen RNA was approximately the same. The incorporation into spleen DNA was enhanced to a much greater degree. Administration of pyridoxine 24hr. before the rats were killed reversed the changes in incorporation of radioactivity from [¹⁴C]formate. 3. In pyridoxine deficiency, the incorporation of radioactivity from dl-[3-¹⁴C]serine, [8-¹⁴C]adenine, [Me-³H]thymidine and [2-¹⁴C]deoxyuridine was decreased. The incorporation of radioactivity from l-[Me-¹⁴C]methionine was not affected. No noteworthy differences in the effect of pyridoxine deficiency on the incorporation of radioactivity from dl-[3-¹⁴C]serine into DNA and RNA were observed, whereas the effect of the deficiency on the incorporation of radioactivity from [8-¹⁴C]adenine into spleen DNA was somewhat greater than that into spleen RNA. Administration of pyridoxine 24hr. before the rats were killed reversed the changes in incorporation of radioactivity from [3-¹⁴C]serine and [8-¹⁴C]adenine. 4. The adverse effects of pyridoxine deficiency on the biosynthesis of nucleic acids and cell multiplication are discussed in relation to the role of pyridoxal phosphate in the production of C₁ units via the serine-hydroxymethylase reaction.     

Lipid-protein interactions of erythrocyte membranes: comparison of normal O, Rh (D) positive with the rare O, Rh null

Phospholipase A₂ modification of lipid-protein interactions of normal O,Rh(D) positive erythrocyte membranes increased the fluorescence intensity of the membrane bound probe, 1-anilinonaphthalene-8-sulfonate (ANS) and increased the N-1-[¹⁴C]-ethyl maleimide ([¹⁴C]-NEM) labeling of sulfhydryl groups in two proteins of molecular weight >200,000. In marked contrast, phospholipase A₂ modification of the rare phenotype O,Rh_null membranes resulted in no significant increase in ANS fluorescence or labeling of sulfhydryl groups by [¹⁴C] NEM. Since the O,Rh_null erythrocytes demonstrated an increased osmotic fragility and decreased survival time, the fluorescence and sulfhydryl labeling data support the conclusion that hydrophobic bonding between β-fatty acid side chains and non-polar regions of asymmetric proteins is necessary for maintaining the native structure of the O,Rh(D) positive membrane. Comparative studies with phospholipase C or D implied that ionic bonding played a similar though less important structural role in both membranes.     

Modified two-dimensional electrophoresis for identification and autoradiography of ribosomal proteins reacted withp-chloromercuribenzoate

Ribosomal proteins labelled with [¹⁴C]PCMB, a reversibly reacting sulfhydryl reagent, lose most of their radioactivity when separated by the conventional two-dimensional polyacrylamide gel electrophoresis. Therefore, the two-dimensional method was modified to insure stability of the PCMB-protein complex during the procedure. Proteins ofEscherichia coli ribosomes were separated by the modified method, and those which reacted with [¹⁴C]PCMB were identified by counting of stained spots and by autoradiography of dried gels.     

A sensitive fluorimetric procedure for the determination of aliphatic epoxides under physiological conditions

Ribose 1-phosphate has been measured in rat tissues by an enzymatic radioactive assay. The sugar phosphate is converted into [¹⁴C]inosine via the two following combined reactions: ribose 1-phosphate + [¹⁴C]adenine ? [¹⁴C]adenosine + phosphate (adenosine phosphorylase); [¹⁴C]adenosine + H₂O → [¹⁴C]inosine + NH₃ (adenosine deaminase). Tissue extracts are incubated in the presence of excess [¹⁴C]adenine. The radioactivity of inosine, separated by a thin-layer chromatographic system, is a measure of ribose 1-phosphate present in tissue extracts. Liver was found to contain the highest level of ribose 1-phosphate (ca. 800 nmol/g wet wt).     

Glucose metabolism in anaerobic rice seedlings

More than 80% of the radioactivity from [U-¹⁴C]glucose metabolised by anaerobic rice seedlings or by excised roots or coleoptiles was recovered as ethanol plus CO₂; less than 5% was recovered as water-soluble acidic components. Rates of ¹⁴CO₂ formation from [U-¹⁴C]glucose were similar in roots and coleoptiles in both N₂ and air atmospheres. More ¹⁴CO₂ was formed from [U-¹⁴C]glucose than could be accounted for by ethanolic fermentation, and the specific yields of ¹⁴CO₂ from [6-¹⁴C]glucose and [1-¹⁴C]glucose gave unusually high C-6/C-1 ratios (1.7) in the anaerobic coleoptile. The results may indicate that appreciable pentan synthesis occurs in the anaerobic coleoptile.     

Preparation, Characterization, and Microbial Degradation of Specifically Radiolabeled [14C]Lignocelluloses from Marine and Freshwater Macrophytes

Specifically radiolabeled [¹⁴C-lignin]lignocelluloses were prepared from the aquatic macrophytes Spartina alterniflora, Juncus roemerianus, Rhizophora mangle, and Carex walteriana by using [¹⁴C]phenylalanine, [¹⁴C]tyrosine, and [¹⁴C]cinnamic acid as precursors. Specifically radiolabeled [¹⁴C-polysaccharide]lignocelluloses were prepared by using [¹⁴C]glucose as precursor. The rates of microbial degradation varied among [¹⁴C-lignin]lignocelluloses labeled with different lignin precursors within the same plant species. To determine the causes of these differential rates, [¹⁴C-lignin]lignocelluloses were thoroughly characterized for the distribution of radioactivity in nonlignin contaminants and within the lignin macromolecule. In herbaceous plants, significant amounts (8 to 24%) of radioactivity from [¹⁴C]phenylalanine and [¹⁴C]tyrosine were found associated with protein, although very little (3%) radioactivity from [¹⁴C]cinnamic acid was associated with protein. Microbial degradation of radiolabeled protein resulted in overestimation of lignin degradation rates in lignocelluloses derived from herbaceous aquatic plants. Other differences in degradation rates among [¹⁴C-lignin]lignocelluloses from the same plant species were attributable to differences in the amount of label being associated with ester-linked subunits of peripheral lignin. After acid hydrolysis of [¹⁴C-polysaccharide]lignocelluloses, radioactivity was detected in several sugars, although most of the radioactivity was distributed between glucose and xylose. After 576 h of incubation with salt marsh sediments, 38% of the polysaccharide component and between 6 and 16% of the lignin component (depending on the precursor) of J. roemerianus lignocellulose was mineralized to ¹⁴CO₂; during the same incubation period, 30% of the polysaccharide component and between 12 and 18% of the lignin component of S. alterniflora lignocellulose was mineralized.     

A Study of Formate Production and Oxidation in Leaf Peroxisomes during Photorespiration

When glycolate was metabolized in peroxisomes isolated from leaves of spinach beet (Beta vulgaris L., var. vulgaris) formate was produced. Although the reaction mixture contained glutamate to facilitate conversion of glycolate to glycine, the rate at which H₂O₂ became “available” during the oxidation of [1-¹⁴C]glycolate was sufficient to account for the breakdown of the intermediate [1-¹⁴C]glyoxylate to formate (C₁ unit) and ¹⁴CO₂. Under aerobic conditions formate production closely paralleled ¹⁴CO₂ release from [1-¹⁴C]glycolate which was optimal between pH 8.0 and pH 9.0 and was increased 3-fold when the temperature was raised from 25 to 35 C, or when the rate of H₂O₂ production was increased artificially by addition of an active preparation of fungal glucose oxidase.     

Preparation of [U-14C]-labelled glycogen, maltosaccharides, maltose, and D-glucose by photoassimilation of 14CO2 in Anacystis nidulans and selective enzymic degradation.

A procedure is described for the isolation from the phototrophic procaryole Anacystis nidulans of [U-¹⁴C]-labelled glycogen, with high specific radioactivity,formed when NaH¹⁴CO₃ was added to non-dividing cells that continued to photoassimilate CO₂. [U-¹⁴C]-Labelled glycogen was then treated with isoamylase (EC 3.2.1.68), isoamylase plus beta-amylase (EC 3.2.1.2), or glucoamylase (EC 3.2.1.3) to give [U-¹⁴C]-labelled maltosaccharides, maltose-U-¹⁴C, or d-glucose-U-¹⁴C, respectively.