Production of S-lactoylglutathione by glycerol-adapted Saccharomyces cerevisiae and genetically engineered Escherichia coli cells

Summary The enzymatic production of S-lactoylglutathione was studied by applying glyoxalase I to glycerol-grown cells of Saccharomyces cerevisiae and Escherichia coli cells dosed with Pseudomonas putida glyoxalase I gene. The glyoxalase I in S. cerevisiae cells was markedly induced when the cells were grown on glycerol. The activity of the enzyme in glycerol-grown cells was more than 20-fold higher compared with that of the glucose-grown cells. By using extracts of glycerol-grown yeast cells, about 5 mmol/1 (2 g/l) of S-lactoylglutathione was produced from 10 mM methylglyoxal and 50 mM glutathione within 1 h. The extracts of E. coli cells carrying a hybrid plasmid pGI423, which contains P. putida glyoxalase I gene, showed approximately 170-fold higher glyoxalase I activity than that of E. coli cells without pGI423. The extracts were used for production of S-lactoylglutathione and, under optimal conditions, about 40 mmol/l (15 g/l) of S-lactoylglutathione was produced from 50 mM methylglyoxal and 100mM glutathione within 1 h.     

Purification and characterization of glyoxalase II from Hansenula mrakii

Glyoxalase II [S-(2-hydroxyacyl)glutathione hydrolase], one of the components of the glyoxalase system, catalyzes the hydrolysis of S-lactoylglutathione to glutathione and d-lactic acid. The enzyme was partially purified from the yeast Hansenula mrakii IFO 0895 by successive column chromatographies and polyacrylamide gel electrophoresis. The molecular weight of the enzyme was estimated to be 22,000 daltons by gel-filtration of Sephadex G-150 column chromatography and 24,000 daltons by SDS-polyacrylamide gel electrophoresis. The enzyme was specific to S-lactoyglutathione and S-acetylglutathione. The activity of the enzyme was strongly inhibited by Cu²⁺, p-chloromercuribenzoate and HgCl₂. The enzyme activity was also inhibited by hemimercaptal, a non-enzymatic condensation product between glutathione and methylglyoxal.     

Unique regulation of glyoxalase I activity during osmotic stress response in the fission yeast <Emphasis Type="Italic">Schizosaccharomyces pombe</Emphasis>: neither the mRNA nor the protein level of glyoxalase I increase under conditions that enhance its activity

Glyoxalase I is a ubiquitous enzyme that catalyzes the conversion of methylglyoxal, a toxic 2-oxoaldehyde derived from glycolysis, to S-D-lactoylglutathione. The activity of glyoxalase I in the fission yeast Schizosaccharomyces pombe was increased by osmotic stress induced by sorbitol. However, neither the mRNA levels of its structural gene nor its protein levels increased under the same conditions. Cycloheximide blocked the induction of glyoxalase I activity in cells exposed to osmotic stress. In addition, glyoxalase I activity was increased in stress-activated protein kinase-deficient mutants (wis1 and spc1). We present evidence for the post-translational regulation of glyoxalase I by osmotic stress in the fission yeast.     

Galacto-oligosaccharide production by a thermostable recombinant β-galactosidase from <Emphasis Type="Italic">Thermotoga maritima</Emphasis>

Summary A β-galactosidase from Thermotoga maritima produced galacto-oligosaccharides (GOS) from lactose by transgalactosylation when expressed in Escherichia coli. The enzyme activity for GOS production was maximal at pH 6.0 and 90 °C. In thermal stability experiments, the enzyme followed first-order kinetics of pH and thermal inactivation, and half-lives at pH 5.0, pH 8.0, 80 °C, and 95 °C were 27 h, 82 h, 41 h, and 14 min, respectively, suggesting that the enzyme was stable below 80 °C and in the pH range of 5.0–8.0. Mn²⁺ was the most effective divalent cation for GOS production. Cu²⁺ and EDTA inhibited more than 84% of enzyme activity. GOS production increased with increasing lactose concentrations and peaked at 500 g lactose/l. Among tested enzyme concentrations, the highest production of GOS was obtained at 1.5 units enzyme/ml. Under the optimal conditions of pH 6.0, 80 °C, 500 g lactose/l, and 1.5 units enzyme/ml, GOS production was 91 g/l for 300 min, with a GOS productivity of 18.2 g/l · h and a conversion yield of GOS to lactose of 18%.     

Production and properties of carboxymethylcellulase (endo-1,4-β-glucanase) fromCurvularia lunata

An extracellular carboxymethylcellulase (endo-1,4--glucanase) fromCurvularia lunata, grown at 30°C with an initial pH of 6.0, had optimal activity at pH 4.8 and 50°C. The enzyme was unstable above 50°C. The enzyme had aK _m for carboxymethylcellulose of 0.97 g/l and aV _max of 5.4 IU/ml.     

Microbial production of (S)-1-phenyl-1,3-propanediol by stereospecific reduction of 3-hydroxy-1-phenylpropane-1-one

A novel microbial method of synthesizing (S)-1-phenyl-1,3-propanediol [(S)-PPD] was developed in this study. Our laboratory stock cultures were screened for microorganisms that stereospecifically produced (S)-PPD from 3-hydroxy-1-phenylpropane-1-one (HPPO) using an intact cell system. Of the 828 strains examined (321 bacteria, 233 yeasts and 274 molds), certain strains of Williopsis saturnus var. mrakii and Cryptococcus albidus were found to produce (S)-PPD with over 99% enantiomeric excess (e.e.). Screening identified W. saturnus var. mrakii AJ-5620 as the most productive strain, and this strain was used for further experiments. The (S)-PPD-producing reaction using intact W. saturnus var. mrakii AJ-5620 cells was carried out by successive feeding of HPPO. A total (S)-PPD yield of 9.9 g/l was produced in 20 h. The molar yield was 81% and the optical purity of the (S)-PPD produced was over 99% e.e.     

Purification and characterization of glyoxalase I from Hansenula mrakii

Glyoxalase I was purified from Hansenula mrakii IFO 0895 which was resistant to 25 mM methylglyoxal. The molecular weight of the purified enzyme was calculated to be 38,000 by both gel-filtration of Sephadex G-150 and SDS-PAGE. The enzyme was almost specific to methylglyoxal (K_m = 0.91 mM). The activity of the enzyme was not inhibited by metal ion chelators such as EDTA, which is a potent inhibitor for glyoxalase Is from other sources.     

Characterization of fructose 6 phosphate phosphoketolases purified from Bifidobacterium species

An extracellular chitin deacetylase activity has been purified to homogeneity from autolyzed cultures of Aspergillus nidulans. This enzyme is an acidic glycoprotein with a pI of 2.75 and a 28% (wt/wt) carbohydrate content. The apparent M _r of the enzyme estimated by SDS/PAGE and Superose 12 (f.p.l.c.) was around 27,000. The enzyme had an optimum pH at 7.0 and was stable in the pH range 4.0–7.5. Its optimum temperature of reaction was 50°C, and it was stable from 30° to 100°C after 1 h of preincubation. The enzyme hydrolyzed glycol chitin and oligomers of N-acetylgucosamine and to a lesser extent chitin, colloidal chitin, carboxymethylchitin, and an -1 3,1 6-N-acetylgalactosamine-galactan among other substances with amido groups, but the enzyme did not hydrolyze peptide bonds. The role of this enzyme could be deacetylation of chitin oligosaccharides during autolysis, after action of endochitinase on cell walls.     

Elucidation of the mechanism of N-demethylation catalyzed by cytochrome P450 monooxygenase is facilitated by exploiting nitrogen-15 heavy isotope effects

Tryptophan indole-lyase (Trpase), PBPRA2532, from Photobacterium profundum SS9, a piezophilic marine bacterium, has been cloned, expressed in Escherichia coli, and purified. The P. profundum Trpase (PpTrpase) exhibits similar substrate specificity as the enzyme from E. coli (EcTrpase). PpTrpase has an optimum temperature for activity at about 30 °C, compared with 53 °C for EcTrpase, and loses activity rapidly (t_1/2 ∼ 30 min) when incubated at 50 °C, while EcTrpase is stable up to 65 °C. PpTrpase retains complete activity when incubated more than 3 h at 0 °C, while EcTrpase has only about 20% remaining activity. Under hydrostatic pressure, PpTrpase remains fully active up to 100 MPa (986 atm), while EcTrpase exhibits only about 10% activity at 100 MPa. PpTrpase forms external aldimine and quinonoid intermediates in stopped-flow experiments with l-Trp, S-Et-l-Cys, S-benzyl-l-Cys, oxindolyl-l-Ala, l-Ala and l-Met, similar to EcTrpase. However, with l-Trp a gem-diamine is observed that decays to a quinonoid complex. An aminoacrylate is observed with l-Trp in the presence of benzimidazole, as was seen previously with EcTrpase [28] but not with S-Et-l-Cys. The results show that PpTrpase is adapted for optimal activity in the low temperature, high pressure marine environment.     

The effect of pH and temperature on haemolysin production by Listeria species

Acetoin reductase (EC 1.1.1.4) from Kluyveromyces marxianus var. marxianus NRRL Y-1196 was found to possess the highest specific activity (3.64 units/mg protein) of the four cultures studied. The enzyme was NADH-dependent and catalysed the conversion of acetoin to 2,3-butanediol. It was stable at 40°C for 30 min, but lost 50% cf its activity after 15 min at 50°C. The optimum pH for the enzymatic reduction of acetoin was 7.0. The K _m values of the crude enzyme for acetoin and NADH were determined to be 0.57 mmol/l and 0.045 mmol/l, respectively.     

Hydrolytic efficiency of Penicillium occitanis cellulase: kinetic aspects

Summary The parameters controlling the activity of the hyper-cellulolytic mutant Pol 6 of Penicillium occitanis cellulase were studied with regard to its efficiency for the hydrolysis of esparto grass cellulose. The optimal operational hydrolysis parameters were pH 5.0, temperature 45–55°C and 32 enzyme units/g of substrate. The maximum conversion ratio to reducing sugars was 84%. The cellulase was thermally quite stable, its activity decreasing by 20% when held at 50°C for 48 h. The cellulase was subject to end-product inhibition, with filter paper activity decreasing by 30% in the presence of 5% glucose. The results generally indicate the high efficiency of P. occitanis cellulase. It compares well with that from other microorganisms such as Trichoderma reesei.     

Immobilization studies of whole microbial cells on transition metal activated inorganic supports

Summary Whole cells of Saccharomyces bayanus, Saccharomyces cerevisiae and Zymomonas mobilis were immobilized by chelation/metal-link processes onto porous inorganic carriers. The immobilized yeast cells displayed much higher sucrose hydrolyzing activities (90–517 U/g) than the bacterial, Z. mobilis, cells (0.76–1.65 U/g). The yeast cells chelated on hydrous metal oxide derivative of pumice stone presented higher initial -d-fructofuranosidase (invertase, EC 3.2.1.26) activity (161–517 U/g) than on other derivatives (90–201 U/g). The introduction of an organic bridge between the cells and the metal activator led to a decrease of the initial activity of the immobilized cells, however S. cerevisiae cells immobilized on the carbonyl derivative of titanium (IV) activated pumice stone, by covalent linkage, displayed a very stable behaviour, which in continuous operation at 30° C show only a slightly decrease on invertase activity for a two month period (half-life=470 days). The continuous hydrolysis of a 2% w/v sucrose solution at 30° C in an immobilized S. cerevisiae packed bed reactor was described by a simple kinetic model developed by the authors (Cabral et al., 1984a), which can also be used to predict the enzyme activity of the immobilized cells from conversion degree data.     

Production,isolation and characterization of extracellular protease of an alkaliphilic strain of Arthrobacter ramosus,MCM B-351 isolated from the alkaline lake of Lonar,India

An extracellular protease was produced by Arthrobacter ramosus isolated from the alkaline lake of Lonar, Buldhana District of Maharashtra, India when grown on a synthetic medium of pH 10 containing casein. The optimum conditions for production were 3.0% initial casein concentration, 2% inoculum of 1 × 10⁸ cells/ml, pH 9.0, temperature 30 °C and shaken culture conditions. The protease was purified by ammonium sulphate precipitation followed by Sephadex G-100 chromatography. Two proteases viz. Arthro I and Arthro II, having molecular weights 21 and 11.4 kDa respectively were isolated. The Arthro II fraction had K _m 395 g/ml and V _max 10.55 g/min for azocasein. The maximum activity of enzyme was at 55 °C and pH 8. It was thermostable (up to 80 °C), alkali stable (pH 12) and stable in commercial detergent. The enzyme may contain a thiol group at the active site.     

Mineralization of phenol and its derivatives by Pseudomonas sp. strain CP4

A Pseudomonas sp. strain, CP4, was isolated that used phenol up to 1.5 g/l as sole source of carbon and energy. Optimal growth on 1.5 g phenol/l was at pH 6.5 to 7.0 and 30°C. Unadapted cells needed 72 h to decrease the chemical oxygen demand (COD) of about 2000 mg/l (from 1 g phenol/l) to about 200 mg/l. Adapted cells, pregrown on phenol, required only 65 h to decrease the COD level to below 100 mg/l. Adaptation of cells to phenol also improved the degradation of cresols. Cell-free extracts of strain CP4 grown on phenol or o-, m- or p-cresol had sp. act. of 0.82, 0.35, 0.54 and 0.32 units of catechol 2,3-dioxygenase and 0.06, 0.05, 0.05 and 0.03 units of catechol 1,2-dioxygenase, respectively. Cells grown on glucose or succinate had neither activity. Benzoate and all isomers of cresol, creosote, hydroxybenzoates, catechol and methyl catechol were utilized by strain CP4. No chloroaromatic was degraded, either as sole substrate or as co-substrate.The authors are with the Department of Microbiology and Bioengineering, Central Food Technological Research Institute, Mysore-570 013, India     

Synthesis of Cyclodextrin glycosyl transferase by immobilized cells of Bacillus circulans

The cells of Bacillus circulans (ATCC 21783) immobilized in sodium alginate gel matrix were able to synthesize the extracellular enzyme, Cyclodextrin glycosyl transferase (CGTase, E.C. 2.4.1.19) which is industrially employed for the preparation of cyclodextrins. Optimization for the maximum production of enzyme was carried out by varying the cell density (3.3–53.5 kg/m³) in the gel and the incubation temperature (30°–42°C). The CGTase activity was found to be the highest (45 units/cm³) with maximum cell loading at 37°C. The reusability of immobilized cells was ascertained by repeated batch experiments. The enzyme activity exhibited was in the range of 50 to 55 units/cm³ in each batch. The continuous synthesis of CGTase by immobilized cells has been demonstrated by operating a fluidized bed reactor at a dilution rate 1.1 · 10^–4 sec^–1 for a period of 15 days. The enzyme activity has decreased to 42.5 units/cm³ from an initial value of 61 units/cm³ during continuous operation.The authors are grateful to Dr. A.D. Damodaran, Director, Regional Research Laboratory, Trivandrum for his keen interest and encouragement and to Department of Biotechnology, Government of India, New Delhi for financial support.     

Purification and properties of a hyperthermoactive α-amylase from the archaeobacterium Pyrococcus woesei

The cultivation of the hyperthermophilic archaeobacterium Pyrococcus woesei on starch under continuous gassing (80% H₂:20% CO₂) caused the formation of 250 U/l of an extremely thermoactive and thermostable -amylase. In a complex medium without elemental sulphur under 80% N₂ and 20% CO₂ atmosphere enzyme production could be elevated up to 1000 U/l. Pyrococcus woesei grew preferentially on poly-and oligosaccharides. The amylolytic enzyme formation was constitutive. Enzyme production was also observed in continuous culture at dilution rates from 0.1 to 0.4 h^-1. A 20-fold enrichment of -amylase was achieved after adsorption of the enzyme onto starch and its desorption by preparative gel electrophoresis. The -amylase consisted of a single subunit with a molecular mass of 70 000 and was catalytically active at a temperature range between 40°C and 130°C. Enzymatic activity was detected even after autoclaving at a pressure of 2 bars at 120°C for 5 h. The purified enzyme hydrolyzed exclusively -1,4-glycosidic linkages present in glucose polymers of various sizes. Unlike many -amylases from anaerobes the enzyme from P. woesei was unable to attack short chain oligosaccharides with a chain length between 2 and 6 glucose units.     

Operational and storage stability of neutral β-mannanase from Bacillus licheniformis

The stability of neutral -mannanase from Bacillus licheniformis during operation and storage was investigated. The enzyme activity decreased by 70% with a hydrolysate of glucomannan at 20 g l^–1 over 30 min at 25 °C. In an enzymatic membrane reactor operated at 50 °C after 24 h, the loss of enzyme activities were 23% and 9% in the absence/presence of the substrate. The residual activities of the enzyme were 21% and 90%, respectively, when stored in 30% (v/v) glycerol solution and in solid state at 4 °C after one year.     

Aminosalicylic acid reduces the antiproliferative effect of hyperglycaemia,advanced glycation endproducts and glycated basic fibroblast growth factor in cultured bovine aortic endothelial cells: Comparison with aminoguanidine

Hyperglycaemia reduces proliferation of bovine aortic endothelial cells in vitro. A similar effect in vivo may contribute to long-term complications of diabetes such as impaired wound-healing and retinopathy.We report the effect of increased glucose concentrations, glycated basic fibroblast growth factor (FGF-2) and bovine serum albumin-derived advanced glycation endproducts (BSA-AGE) on the proliferation of bovine aortic endothelial cells.Glucose (30 and 50 mmol/l) had an antiproliferative effect on endothelial cells. This effect may be mediated through reduced mitogenic activity of FGF-2. The glycation of FGF-2 with 250 mmol/l glucose-6-phosphate led to reduced mitogenic activity compared to native FGF-2. BSA-AGE at concentrations of 10, 50 and 250 g/ml had an antiproliferative effect on cultured endothelial cells.Aminosalicylic acid at a concentration of 200 mol/l proved to be more effective than equimolar concentrations of aminoguanidine in protecting endothelial cells against the antiproliferative effects of both high (30 mmol/l) glucose and 50 g/ml BSA-AGE. FGF-2 glycated in the presence of 4 mmol/l aminosalicylic acid or aminoguanidine retained mitogenic activity compared to that glycated in their absence.Compounds like aminoguanidine and, in particular, aminosalicylic acid protect endothelial cells against glucose-mediated toxicity and may therefore have therapeutic potential.     

Continuous production of fructooligosaccharides from sucrose by immobilized fructosyltransferase

The productivity of the continuous production of fructooligosaccharides from sucrose was investigated by fructosyltransferase immobilized onto a high-porous ion exchange resin was optimal with 600 g sucrose/l at a flow rate of 2.7 h^–1 expressed as a superficial space velocity. When the column was operated at 50 °C, about 8% loss of the initial activity of immobilized enzyme was observed after 30 days continuous operation, achieving high productivity of 1174 g/l · h.     

CHOLINE ACETYLTRANSFERASE, ACETYLCHOLINESTERASE AND AROMATIC l-AMINO ACID DECARBOXYLASE IN SINGLE IDENTIFIED NERVE CELL BODIES FROM SNAIL HELIX ASPERSA

—The distribution of choline acetyltransferase, aromatic l -amino acid decarboxylase and acetylcholinesterase in the nervous system of Helix aspersa has been studied using homogenates of whole ganglia, microdissection from freeze-dried sections and dissection of single neurons from fresh tissue. Choline acetyltransferase was found in both the cell body and neuropil layers of all the Helix ganglia. The enzyme was not specifically localized to any ganglion or region of ganglion. Between 10 and 30 per cent of the isolated single cell bodies contained the enzyme. The enzymic activity corresponded to 50–200 mmol ACh/1 cell bodies/h. Choline acetyltransferase is probably a specific marker for cholinergic cells in this species. Aromatic l -amino acid decarboxylase was more selectivity localized and its distribution corresponded well with that of monoamine containing cells as visualized by the fluorescence histochemical technique. A large proportion of cell bodies were localized in the boundary between the visceral and right parietal ganglia and in the pedal ganglion. The other ganglia contained few such cells. The activity of aromatic l -amino acid decarboxylase corresponded 10–50 mmol dopamine/1 cell bodies/h. A method was developed to measure the enzyme activity towards 5-hydroxytryptophan and DOPA in single cells simultaneously. The ratio between the activity towards both substrates did not vary significantly for the different cells. The enzyme is probably a specific marker for monoamine cells, but cannot be used to differentiate between the different monoamine cells. Acetylcholinesterase was uniformly distributed in the ganglia and was probably present in all nerve cells.