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PubMed1971

Studies on the Biosynthesis and Metabolism of delta-Aminolevulinic Acid in Chlorella.

The regulation of chlorophyll synthesis in Chlorella was examined at the level of the formation and metabolism of delta-aminolevulinic acid. delta-Aminolevulinic acid synthetase activity could not be detected in broken cell preparations, and exogenously supplied delta-aminolevulinic acid was taken up only in the presence of dimethylsulfoxide, with a corresponding production of porphobilinogen.The delta-aminolevulinic acid dehydratase of Chlorella has a pH optimum of 7.8 and at this pH the Michaelis constant for delta-aminolevulinic acid is 0.13 millimolar.delta-Aminolevulinic acid excretion in the presence of levulinic acid, a competitive inhibitor of delta-aminolevulinic acid dehydratase, allowed measurement of the relative rates of delta-aminolevulinic acid synthesis under various growth conditions. A mutant which requires light for chlorophyll synthesis also requires light for delta-aminolevulinic acid accumulation in the presence of levulinic acid. This same mutant has 40% of the delta-aminolevulinic acid dehydratase activity of the wild-type Chlorella during growth in the dark on glucose.The necessity for protein synthesis during chlorophyll synthesis is due primarily to the requirement for protein synthesis during delta-aminolevulinic acid formation.It is concluded that the rate of chlorophyll formation and the cellular chlorophyll content are regulated by the relative rates of synthesis and breakdown of an enzyme responsible for delta-aminolevulinic acid biosynthesis and that this enzyme has an in vivo lifetime of about 30 minutes.

Journal Article↗
PubMed2006

Effects of medium composition on production of 5-aminolevulinic acid by recombinant Escherichia coli.

The recombinant Escherichia coli BL21(DE3) harboring hemA from Agrobacterium radiobacter, which was engineered in our previous work, was used for the extracellular production of 5-aminolevulinic acid (ALA). The effects of various physiological factors, such as the concentrations of precursors (glycine, succinic acid and glucose) and the inhibitor 5-aminolevulinate dehydratase (levulinic acid), on the ALA accumulation in the fermentation broth were investigated in both shake flasks and a jar fermentor. Among these precursors, glycine exhibited the strongest ability to inhibit cell growth, while glucose mainly inhibited ALA formation. The optimum initial concentrations of glycine, succinic acid and glucose were found to be 2.0, 10.0 and 2.0 g/l, respectively. Levulinic acid (LA; 30 mM) was fed to the fermentation broth at the end of the exponential cell growth phase (about 8 h), and the intracellular activity of ALA dehydratase was efficaciously suppressed. Repeating the optimum composition of the medium in a stirred tank fermenter resulted in 1.49 g/l ALA. Furthermore, the fed batch of the precursors and inhibitor further increased ALA production up to 3.01 g/l.

Aldehyde Oxidoreductases↗
PubMed1976

Exacerbation of porphyria during treatment of pulmonary tuberculosis.

Several attacks of acute intermittent porphyria complicated the treatment of a patient with pulmonary tuberculosis. To determine whether the attacks were drug-induced, the ability of a variety of antituberculous drugs to induce (delta)-amino-levulinic acid synthetase activity in a rat liver model was assessed. Pyrazinamide was found to be capable of significantly inducing amino-levulinic acid synthetase activity; the other antituberculous drugs caused either slight or no induction of amino-levulinic acid synthetase. The data suggest that pyrazinamide was capable of causing an exacerbation of the patient's porphyria. Tuberculosis, by causing debility, may also have aggravated this patient's previously latent porphyria.

5-Aminolevulinate Synthetase↗
PubMed1982

Biochemical characterization of the OXI mutants of the yeast Saccharomyces cerevisiae.

OXI mutants in Saccharomyces cerevisiae lack a functional cytochrome c oxidase. Wild type and OXI mutants were grown in the presence of radioactive delta-amino[14C]levulinic acid, a precursor of porphyrin and heme, and [3H]mevalonic acid, a precursor of the alkyl side-chain of heme a. SDS polyacrylamide gel electrophoresis of the delipidated mitochondria showed that delta-amino[14C]levulinic acid was distributed into three bands migrating in the regions of Mr 28 000, 13 500, and 10 000, while [3H]mevalonic acid was found in a single band with apparent Mr of 10 000. The immunoprecipitates obtained by incubating the solubilized mitochondria of any OXI mutant with antibodies against cytochrome c oxidase, showed, after delipidation, a high specific radioactivity due to delta-amino[14C]levulinic acid and [3H]mevalonic acid. This suggested that a prophyrin a was present in all these OXI mutants. HCl fractionation confirmed the presence of porphyrin a in the apooxidase of these mutants. Atomic absorption spectra of the immunoprecipitate of cytochrome c oxidase showed that copper was not detectable in the mutant OXI IIIa which lacked subunit 1, but was present in the mutant OXI IIIb, which exhibited a minor alteration in the electrophoretic mobility of subunit 1. In OXI I and II mutants there was a 50% reduction in the amount of copper in the immunoprecipitated cytochrome c oxidase. These observations may be interpretable as follows: (1) alterations in polypeptide biosynthesis due to the OXI mutations lead to an improper configuration of cytochrome c oxidase, so that ferrochelatase cannot transfer iron into porphyrin a; (2) subunit I is the binding site for copper, but the mutations in subunits II and III alter the binding site of one of the two copper atoms in subunit I.

Aminolevulinic Acid↗
PubMedDate not supplied

Effect of inhibitors released during steam-explosion treatment of poplar wood on subsequent enzymatic hydrolysis and SSF.

Steam-exploded (SE) poplar wood biomass was hydrolyzed by means of a blend of Celluclast and Novozym cellulase complexes in the presence of the inhibiting compounds produced during the preceding steam-explosion pretreatment process. The SE temperature and time conditions were 214 degrees C and 6 min, resulting in a log R(0) of 4.13. In enzymatic hydrolysis tests at 45 degrees C, the biomass loading in the bioreactor was 100 g(DW)/L (dry weight) and the enzyme-to-biomass ratio 0.06 g/g(DW). The enzyme activities for endo-glucanase, exo-glucanase, and beta-glucosidase were 5.76, 0.55, and 5.98 U/mg, respectively. The inhibiting effects of components released during SE (formic, acetic, and levulinic acids, furfural, 5-hydroxymethyl furfural (5-HMF), syringaldehyde, 4-hydroxy benzaldehyde, and vanillin) were studied at different concentrations in hydrolysis runs performed with rinsed SE biomass as model substrate. Acetic acid (2 g/L), furfural, 5-HMF, syringaldehyde, 4-hydroxybenzaldehyde, and vanillin (0.5 g/L) did not significantly effect the enzyme activity, whereas formic acid (11.5 g/L) inactivated the enzymes and levulinic acid (29.0 g/L) partially affected the cellulase. Synergism and cumulative concentration effects of these compounds were not detected. SSF experiments show that untreated SE biomass during the enzymatic attack gives rise to a nonfermentable hydrolysate, which becomes fermentable when rinsed SE biomass is used. The presence of acetic acid, vanillin, and 5-HMF (0.5 g/L) in SSF of 100 g(DW) /L biomass gave rise to ethanol yields of 84.0%, 73.5%, and 91.0% respectively, with respective lag phases of 42, 39, and 58 h.

Bioreactors↗
PubMed2006

Polyhydroxyalkanoate copolymers from forest biomass.

The potential for the use of woody biomass in poly-beta-hydroxyalkanoate (PHA) biosynthesis is reviewed. Based on previously cited work indicating incorporation of xylose or levulinic acid (LA) into PHAs by several bacterial strains, we have initiated a study for exploring bioconversion of forest resources to technically relevant copolymers. Initially, PHA was synthesized in shake-flask cultures of Burkholderia cepacia grown on 2.2% (w/v) xylose, periodically amended with varying concentrations of levulinic acid [0.07-0.67% (w/v)]. Yields of poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate) [P(3HB-co-3HV)] from 1.3 to 4.2 g/l were obtained and could be modulated to contain from 1.0 to 61 mol% 3-hydroxyvalerate (3HV), as determined by 1H and 13C NMR analyses. No evidence for either the 3HB or 4HV monomers was found. Characterization of these P(3HB-co-3HV) samples, which ranged in molecular mass (viscometric, Mv) from 511-919 kDa, by differential scanning calorimetry and thermogravimetric analyses (TGA) provided data which were in agreement for previously reported P(3HB-co-3HV) copolymers. For these samples, it was noted that melting temperature (Tm) and glass transition temperature (Tg) decreased as a function of 3HVcontent, with Tm demonstrating a pseudoeutectic profile as a function of mol% 3HV content. In order to extend these findings to the use of hemicellulosic process streams as an inexpensive carbon source, a detoxification procedure involving sequential overliming and activated charcoal treatments was developed. Two such detoxified process hydrolysates (NREL CF: aspen and CESF: maple) were each fermented with appropriate LA supplementation. For the NREL CF hydrolysate-based cultures amended with 0.25-0.5% LA, P(3HB-co-3HV) yields, PHA contents (PHA as percent of dry biomass), and mol% 3HV compositions of 2.0 g/l, 40% (w/w), and 16-52 mol% were obtained, respectively. Similarly, the CESF hydrolysate-based shake-flask cultures yielded 1.6 g/l PHA, 39% (w/w) PHA contents, and 4-67 mol% 3HV compositions. These data are comparable to copolymer yields and cellular contents reported for hexose plus levulinic acid-based shake-flask cultures, as reported using Alcaligenes eutrophus and Pseudomonas putida. However, our findings presage a conceivable alternative, forestry-based biorefinery approach for the production of value-added biodegradable PHA polymers. Specifically, this review describes the current and potential utilization of lignocellulosic process streams as platform precursors to PHA polymers including hemicellulosic hydrolysates, residual cellulose-derived levulinic acid, tall oil fatty acids (Kraft pulping residual), and lignin-derived aromatics.

Alcaligenes↗
PubMedDate not supplied

Liquid chromatographic determination of protein acid hydrolysate content in blended soy sauce.

Five methods were investigated for the determination of levulinic acid in soy sauce to determine the addition of protein hydrolysate, mainly acid hydrolysate of defatted soybeans. Best results were obtained by using liquid chromatography (LC) with 0.004 M HClO4 as the mobile phase and bromcresol purple as a post-column reagent. An innovative LC method with 0.1% H3PO4 as eluant was developed for determination of levulinic acid at 280 nm in soy sauce. This was the most time-saving method.

Chromatography, Liquid↗
PubMed1986

Profiling of organic acids and polyols in nerves of uraemic and non-uraemic patients.

Organic acids, polyols and lipid-bound polyols in the cauda equina nerves of uraemic patients and non-uraemic patients were analysed with high-resolution gas chromatography-mass spectrometry. In the uraemic nervous tissue, the concentrations of myoinositol and 4-hydroxyphenylacetic acid were increased. Levulinic acid was first detected in the nervous tissue as a normal component. 1-Deoxyglucose and free and lipid phosphatide scylloinositol were detected in the nervous tissue as normal components.

Acids↗
PubMed1974

The Biosynthesis of delta-Aminolevulinic Acid in Higher Plants: I. Accumulation of delta-Aminolevulinic Acid in Greening Plant Tissues.

delta-Aminolevulinic acid dehydrase activity in cucumber (Cucumis sativus L. var. Alpha green) cotyledons did not change as the tissue was allowed to green for 24 hours. delta-Aminolevulinic acid accumulated in greening cucumber cotyledons, and barley (Hordeum sativum L. var. Numar) and bean (Phaseolus vulgaris L. var. Red Kidney) leaves incubated in the presence of levulinic acid, a specific competitive inhibitor of delta-aminolevulinic acid dehydrase. The rate of delta-aminolevulinic acid accumulation in levulinic acid-treated cucumber cotyledons paralleled the rate of chlorophyll accumulation in the controls, and the quantity of delta-aminolevulinic acid accumulated compensated for the decrease in chlorophyll accumulation. When levulinic acid-treated cucumber cotyledons were returned to darkness, delta-aminolevulinic acid accumulation ceased.delta-Aminolevulinic acid accumulation showed an absolute requirement for oxygen and was inhibited drastically by cyanide and azide, and to a lesser extent by arsenite and malonate. 2,4-Dinitrophenol, 3-(3,4-dichlorophenyl)-1,1-dimethyl urea, sodium fluoroacetate, and hydroxylamine hydrochloride showed no effect under the conditions tested. Freezing and thawing of the tissue completely prevented the accumulation of delta-aminolevulinic acid.The findings of this investigation are consistent with the hypothesis that delta-aminolevulinic acid is a chlorophyll precursor in higher plants, and that chlorophyll biosynthesis is regulated at the level of the formation of delta-aminolevulinic acid.

Journal Article↗
PubMed1980

Chloroplast Biogenesis 31: DETECTION OF AN INHIBITOR OF PROTOCHLOROPHYLL BIOSYNTHESIS IN CUCUMBER COTYLEDONS.

An extract from cucumber cotyledons was shown to cause an inhibition of protochlorophyll biosynthesis and accumulation. The extract inhibited the net synthesis of protochlorophyll as well as the incorporation of delta-amino[(14)C]levulinic acid into protochlorophyllide and protochlorophyllide ester by excised cotyledons. The inhibition of delta-amino[(14)C]levulinic acid incorporation into the two protochlorophyll species was also observed in isolated etiochloroplasts before and after lysis of the plastids. The inhibition did not appear to involve the oxidation of the delta-aminolevulinic substrate or its translocation across the plastid membrane. Kinetic analysis of the rate of protochlorophyllide and protochlorophyllide ester biosynthesis in the presence and absence of the inhibitor suggested that the mode of inhibition of the two protochlorophyll species was different.

Journal Article↗
PubMed1994

Effect of biosynthetic manipulation of heme on insolubility of Vitreoscilla hemoglobin in Escherichia coli.

Vitreoscilla hemoglobin (VHb) is accumulated at high levels in both soluble and insoluble forms when expressed from its native promoter on a pUC19-derived plasmid in Escherichia coli. Examination by atomic absorption spectroscopy and electron paramagnetic resonance spectroscopy revealed that the insoluble form uniformly lacks the heme prosthetic group (apoVHb). The purified soluble form contains heme (holoVHb) and is spectroscopically indistinguishable from holoVHb produced by Vitreoscilla cells. This observation suggested that a relationship may exist between the insolubility of apoVHb and biosynthesis of heme. To examine this possibility, a series of experiments were conducted to chemically and genetically manipulate the formation and conversion of 5-aminolevulinic acid (ALA), a key intermediate in heme biosynthesis. Chemical perturbations involved supplementing the growth medium with the intermediate ALA and the competitive inhibitor levulinic acid which freely cross the cell barrier. Genetic manipulations involved amplifying the gene dosage for the enzymes ALA synthase and ALA dehydratase. Results from both levulinic acid and ALA supplementations indicate that the level of soluble holoVHb correlates with the heme level but that the level of insoluble apoVHb does not. The ratio of soluble to insoluble VHb also does not correlate with the level of total VHb accumulated. The effect of amplifying ALA synthase and ALA dehydratase gene dosage is complex and may involve secondary factors. Results indicate that the rate-limiting step of heme biosynthesis in cells overproducing VHb does not lie at ALA synthesis, as it reportedly does in wild-type E. coli (S. Hino and A. Ishida, Enzyme 16:42-49, 1973).

Bacterial Proteins↗
PubMed1978

Lead poisoning in feeder calves.

A group of 90 feeder calves was accidentally exposed to lead for approximately 30 days. The source of the intoxication was determined to be contamination of feed ingredients from a railroad car. Fourteen calves died and 8 more were clinically affected. Blood samples were obtained from 24 exposed calves (16 clinically normal and 8 intoxicated), and the samples were analyzed for lead, delta-amino levulinic acid dehydrase activity, and free erythrocyte porphyrin. Blood lead values ranged from 0.44 to 1.16 parts per million. Amino levulinic acid dehydrase activity was not affected enough to be of diagnostic value, whereas free erythrocyte porphyrin was increased dramatically and consistently in lead-exposed cattle.

Animal Feed↗
PubMed1980

Development of Enzymes Involved in Photosynthetic Carbon Assimilation in Greening Seedlings of Maize (Zea mays).

Upon illumination of dark-grown maize seedlings (5 days old) with incandescent light, there occurred a nearly simultaneous increase, after a certain lag period, in the activities of enzymes engaged in the C(4) pathway and the Calvin-Benson cycle. The light-induced biosynthesis of chlorophyll (a and b) precedes the increase in enzyme activities and proceeds without lag phase. A diphasic feature in the elevation of enzyme activities as a function of the intensities of light provided was observed; the increase in enzyme activities was enhanced by light intensities greater than 10(3) ergs per square centimeter per second in comparison with light of lower intensities. Under light intensities greater than 10(3) ergs per square centimeter per second, the simultaneous addition of levulinic acid, which inhibited chlorophyll formation, markedly reduced the increase of enzyme activities. However, neither the diphasic light effect nor the inhibitory effect of levulinic acid was observed with ribulose-1,5-bisphosphate carboxylase. The enzyme activities in the dark-grown maize seedlings were enhanced by a brief irradiation with the red light and the red light effect was reversed by the following far red light treatment. The red light-induced increase in the enzyme activities did not accompany chlorophyll synthesis, and was completely inhibited by cycloheximide, indicating that enzyme synthesis rather than activation might be involved. Light may play a dual role in enzyme induction; one is as an energy source through the photosystems at high intensities and the other is presumably as a signal mediated by phytochrome at low intensities.

Journal Article↗
PubMed2001

Development of a process for the biotechnological large-scale production of 4-hydroxyvalerate-containing polyesters and characterization of their physical and mechanical properties.

A process for the large-scale production of 4-hydroxyvalerate (4HV)-containing biopolyesters with a new monomer composition was developed by means of high-cell-density cultivation applying recombinant strains of Pseudomonas putida and Ralstonia eutropha, harboring the PHA-biosynthesis genes phaC and phaE of Thiocapsa pfennigii. Cell densities of about 20 g/L revealing a PHA content of 52% (w/w) and a molar fraction of 4HV of up to 15.4 mol % were obtained by a two-stage fed-batch cultivation process at a 25-L scale using octanoic acid during the growth phase and levulinic acid for the accumulation of 4HV-containing polyesters. Besides 4HV the polyester contained significant amounts of both 3-hydroxybutyric acid (3HB) and 3-hydroxyvaleric acid (3HV) and traces of 3-hydroxyhexanoic acid (3HHx) and 3-hydroxyoctanoic acid (3HO). With glucose or gluconic acid as the growth substrate, the components of the polyester could be reduced to mainly 3HV and 4HV with only a negligible fraction of 3HB, resulting in a polyester with a new composition. Scale-up of the cultivation process to a 500-L scale was successfully performed, resulting in the production of these polyesters at a pilot plant scale. Short-term shifts in temperature and pH resulted in the formation of cell agglomerates of about 50-100 microm by which the effectiveness of the semicontinuous centrifugation process was drastically increased. Washing of the freeze-dried cells with boiling methanol significantly shortened the extraction process and resulted in a polyester of higher purity. The physical and mechanical properties of these copolyesters were characterized by means of size exclusion chromatography, dynamic mechanical analysis, differential scanning calorimetry, stress-strain measurements, and measurements of the viscosity of the solution. The copolyesters were cast into films, spun to fibers, or processed into test bars by melt spinning and injection molding, respectively. They revealed an almost entirely amorphous structure and consequently were sticky and lacked strength. However they showed high thermal stability and an unusually high elongation at break of about 200%; the molecular weights (M(w)) were between 2.0 x 10(5) and 3.3 x 10(5) g/mol. It was shown that 4HV-containing polyesters belong to the class of thermoplastic elastomeres.

Aerobiosis↗
PubMed1978

Phycobiliprotein synthesis in protoplasts of the unicellular cyanophyte, Anacystis nidulans.

Stable and metabolically active protoplasts were prepared from the unicellular cyanophyte, Anacystis nidulans, by enzymatic digestion of the cell wall with 0.1% lysozyme. The yield of protoplasts from intact algal cells was approx. 50%. Incorporation of L-[U-14C]leucine into cold trichloroacetic acid-insoluble material from protoplasts preparations was linear for 1.5 h and continued for an additional 2.5 h. Incorporation of radiolabeled leucine into hot trichloroacetic acid-insoluble material from protoplast preparations demonstrated protein synthesis in protoplasts in vitro. Phycocyanin is the principal phycobiliprotein and allophycocyanin is a minor phycobiliprotein in A. nidulans cells. The light-absorbing chromophore of both of these phycobiliproteins is the linear tetrapyrrole (bile pigment), phycocyanobilin. Radiolabeled phycocyanin and allophycocyanin were isolated from protoplast preparations which had been incubated with L-[U-14]leucine or delta-amino[4-14C] levulinic acid (a precursor of phycocyanobilin). The radio-labeled phycobiliproteins were purified by ammonium sulfate fractionation and ion-exchange chromatography on brushite columns. The specific radioactivity of phycocyanin and allophycocyanin in brushite column eluates (protoplasts incubated with radiolabeled leucine) was 106 000 and 82 000 dpm/mg, respectively. The specific radioactivity of phycocyanin and allophycocyanin in brushite column eluates (protoplasts incubated with radiolabeled delta-aminolevulinic acid) was 33 000 and 38 000 dpm/mg, respectively. Phycobiliproteins from protoplasts incubated with radiolabeled leucine were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 25% of the incorporated radioactivity in protoplast lysates and approx. 60% of the incorporated radioactivity in protoplast lysates and approx. 60% of the incorporated ratioactivity in phycocyanin and allophycocyanin (in brushite column eluates) comigrated with the subunits of these phycobiliproteins on sodium dodecyl sulfate-polyacrylamide gels. Chromic acid degradation of phycobiliproteins from protoplast preparations incubated with delta-amino[4-14C] levulinic acid yielded radiolabeled imides which were derived from the phycocyanobilin chromophore. Imides from radiolabeled phycobiliproteins isolated from protoplast preparations incubated with L-[U-14C]leucine did not contain radioactivity. These results show that both the apoprotein and tetrapyrrolic moieties of phycocyanin and allophycocyanin were synthesized in A. nidulans protoplasts in vitro.

Apoproteins↗
PubMed2004

Inhibition of chlorophyll biosynthesis by mercury in excised etiolated maize leaf segments during greening: effect of 2-oxoglutarate.

Mercury (0.01-1.0 mM) inhibited chlorophyll formation in greening maize leaf segments. However, supplementing incubation medium with 2-oxoglutarate, maintained substantially higher level of chlorophyll in absence of metal after an initial period of 8 hr. On preincubation of leaf segments with HgCl2, per cent inhibition of chlorophyll synthesis by metal was same in the presence and absence of 2-oxoglutarate. Supply of 2-oxoglutarate (0.1-10.0 mM) exerted concentration dependent effect on chlorophyll formation in absence or presence of metal. Increase in delta-amino levulinic acid dehydratase as well as NADH-glutamate synthase activity and decrease in NADH-glutamate dehydrogenase activity by 2-oxoglutarate in the presence of Hg suggested that glutamate for delta-amino levulinic acid synthesis could be made available from NH4+ assimilation via., glutamine synthetase/glutamate synthase pathway during mercury toxicity.

Aminolevulinic Acid↗
PubMed2004

Selection of anion exchangers for detoxification of dilute-acid hydrolysates from spruce.

Six anion-exchange resins with different properties were compared with respect to detoxification of a dilute-acid hydrolysate of spruce prior to ethanolic fermentation with Saccharomyces cerevisiae. The six resins encompassed strong and weak functional groups as well as styrene-, phenol-, and acrylic-based matrices. In an analytical experimental series, fractions from columns packed with the different resins were analyzed regarding pH, glucose, furfural, hydroxymethylfurfural, phenolic compounds, levulinic acid, acetic acid, formic acid, and sulfate. An initial adsorption of glucose occurred in the strong alkaline environment and led to glucose accumulation at a later stage. Acetic and levulinic acid passed through the column before formic acid, whereas sulfate had the strongest affinity. In a preparative experimental series, one fraction from each of six columns packed with the different resins was collected for assay of the fermentability and analysis of glucose, mannose, and fermentation inhibitors. The fractions collected from strong anion-exchange resins with styrene-based matrices displayed the best fermentability: a sevenfold enhancement of ethanol productivity compared with untreated hydrolysate. Fractions from a strong anion exchanger with acrylic-based matrix and a weak exchanger with phenol-based resin displayed an intermediate improvement in fermentability, a four- to fivefold increase in ethanol productivity. The fractions from two weak exchangers with styrene- and acrylic-based matrices displayed a twofold increase in ethanol productivity. Phenolic compounds were more efficiently removed by resins with styrene- and phenol-based matrices than by resins with acrylic-based matrices.

Anion Exchange Resins↗