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PubMed1989

An asymmetric synthesis of (R) and (S)-1-alkoxy-2,3-propanediols including precursors to platelet activating factor.

The titanium-assisted nucleophilic opening of glycidol with primary aliphatic alcohols gives 1-alkoxy-2,3-propanediols. The titanium alkoxide used in the reaction should be the alkoxide of the alcohol used for the reaction. When optically active (S)-glycidol is used in the reaction, (S)-1-alkoxy-2,3-propanediols are obtained without loss of optical activity. When the reaction is carried out at 70-75 degrees C without solvent, the 1-alkoxy-2,3-propanediols are obtained in yields of 45-59%. The regioisomeric 2-alkoxy-1,3-propanediols are found to the extent of 4-6% in the reaction. The optical purity of glycidol can be measured from the high field (500 MHz) nuclear magnetic resonance spectrum of the Mosher ester.

Chemical Phenomena↗

PubMed1984

More accurate determination of the quantity of ice crystallized at low cooling rates in the glycerol and 1,2-propanediol aqueous solutions: comparison with equilibrium.

It is generally assumed that when cells are cooled at rates close to those corresponding to the maximum of survival, once supercooling has ceased, above the eutectic melting temperature the extracellular ice is in equilibrium with the residual solution. This did not seem evident to us due to the difficulty of ice crystallization in cryoprotective solutions. The maximum quantities of ice crystallized in glycerol and 1,2-propanediol solutions have been calculated from the area of the solidification and fusion peaks obtained with a Perkin-Elmer DSC-2 differential scanning calorimeter. The accuracy has been improved by several corrections: better defined baseline, thermal variation of the heat of fusion of the ice, heat of solution of the water from its melting with the residual solution. More ice crystallizes in the glycerol than in the 1,2-propanediol solutions, of which the amorphous residue contains about 40 to 55% 1,2-propanediol. The equilibrium values are unknown in the presence of 1,2-propanediol. With glycerol, in our experiments, the maximum is first lower than the equilibrium but approaches it as the concentration increases. It is not completely determined by the colligative properties of the solutes.

Cryoprotective Agents↗

PubMed1984

Comparison of the cryoprotection of red blood cells by 1,2-propanediol and glycerol.

Red blood cells are cooled in buffered solutions containing 10, 15, 20, 30, or 35% (w/w) 1,2-propanediol or glycerol. Cell survival is measured after cooling to -196 degrees C at rates between 1 and 3500 degrees C/min, followed by rewarming rapidly, except in a few cases. At low cooling rates, where the injuries are due to solution effects, for the same (w/w) concentrations of 15 or 20% (w/w), 1,2-propanediol protects erythrocytes better than glycerol. Differences are still observed when the two cryoprotectants are compared on a mole-fraction basis. At high cooling rates the survival passes through a minimum and then increases again. For the same concentrations, the minimum occurs at much lower cooling rates with 1,2-propanediol than with glycerol, in agreement with the better glass-forming tendency of 1,2-propanediol solutions. These cooling rates almost coincide with those at which the quantity of ice crystallized begins to decrease in the corresponding solutions. Thus, survival seems to be closely related to the glass-forming tendency at the survival minimum, and at higher cooling rates. After the fastest cooling rates, the warming rates necessary to avoid damage on warming are much smaller than those necessary to avoid devitrification. Therefore, in the present experiments the survivals are not related to the stability of the wholly amorphous state. However, injury follows the presumed transition from cubic to hexagonal ice, in erythrocytes as well as in other kinds of cells.

Blood Preservation↗

PubMed1992

Inactivation of propanediol oxidoreductase of Escherichia coli by metal-catalyzed oxidation.

1,2-Propanediol oxidoreductase, which reduces the L-lactaldehyde formed in the fermentation of L-fucose or L-rhamnose to L-1,2-propanediol in E. coli, was inactivated by a component of E. coli cell extracts in the presence of oxygen. Pure propanediol oxidoreductase preparations were shown to be inactivated in vitro by aerobic incubations in the presence of Fe3+ and ascorbate. The Fe3+ ascorbate-mediated inactivation reaction was inhibited by catalase, although not by superoxide dismutase. Under anaerobic conditions, the presence of H2O2 strongly inactivated the enzyme. Propanediol oxidoreductase was rapidly degraded in the presence of oxygen, while the native enzyme displayed high stability as long as no oxygen was present.

Alcohol Oxidoreductases↗

PubMed1976

Growth of a mutant of Escherichia coli K-12 on xylitol by recruiting enzymes for D-xylose and L1,2-propanediol metabolism.

Wild type Escherichia coli K-12 cannot grow on xylitol and we have been unsuccessful in isolating a mutant directly which had acquired this new growth ability. However, a mutant had been selected previously for growth on L-1,2-propanediol as the sole source of carbon and energy. This mutant constitutively synthesized a propanediol dehydrogenase. Recently, we have found that this dehydrogenase fortuitously converted xylitol to D-xylose which could normally be metabolized by E. coli K-12. In addition, it was also discovered that the D-xylose permease fortuitously transported xylitol into the cell. A second mutant was thus isolated from the L-1,2-propanediol-growing mutant that was constitutive for the enzymes of the D-xylose pathway. This mutant could indeed grow on xylitol as the sole source of carbon and energy, by utilizing the enzymes normally involved in D-xylose and L-1,2-propanediol metabolism.

Alcohol Oxidoreductases↗

PubMedDate not supplied

Metabolic engineering of propanediol pathways.

Microbial fermentation is an important technology for the conversion of renewable resources to chemicals. In this paper, we describe the application of metabolic engineering for the development of two new fermentation processes: the microbial conversion of sugars to 1,3-propanediol (1,3-PD) and 1,2-propanediol (1,2-PD). A variety of naturally occurring organisms ferment glycerol to 1,3-PD, but no natural organisms ferment sugars directly to 1,3-PD. We first describe the fed-batch fermentation of glycerol to 1,3-PD by Klebsiella pneumoniae. We then present various approaches for the conversion of sugars to 1,3-PD, including mixed-culture fermentation, cofermentation of glycerol and glucose, and metabolic engineering of a "sugars to 1,3-PD" pathway in a single organism. Initial results are reported for the expression of genes from the K. pneumoniae 1,3-PD pathway in Saccharomyces cerevisiae. The best naturally occurring organism for the fermentation of sugars to 1,2-PD is Thermoanaerobacterium thermosaccharolyticum. We describe the fermentation of several different sugars to 1,2-PD by this organism in batch and continuous culture. We report that Escherichia coli strains engineered to express either aldose reductase or glycerol dehydrogenase convert glucose to (R)-1,2-PD. We then analyze the ultimate potential of fermentation processes for the production of propanediols. Linear optimization studies indicate that, under aerobic conditions, propanediol yields that approach the theoretical maximum are possible and CO2 is the primary coproduct. Without the need to produce acetate, final product titers in the range of 100 g/L should be possible; the high titers and low coproduct levels should make product recovery and purification straightforward. The examples given in this paper illustrate the importance of metabolic engineering for fermentation process development in general.

Biotechnology↗

PubMedDate not supplied

[Synthesis of nucleotide derivatives containing 1-(4-(3-(trifluoromethyl)-3H-diazirin-3-yl)benzamido)-2,3-propanediol for photoaffinity modification of proteins and nucleic acid].

1-(4-(3-(Trifluoromethyl)-3H-diazirin-3-yl)benzamido)-3-O-(4,4'- dimethoxytrityl)-2,3-propanediol phosphoramidite was synthesized and used as a modified unit in the automatic synthesis of oligodeoxyribonucleotides. Pentadecathymidylates with various numbers of 2,3-propanediol moieties substituted with aryl(trifluoromethyl)diazirinyl (ATFMD) were obtained, and the thermal stability of their duplexes with (dA)15 were studied. One ATFMD-propanediol residue was shown to reduce the thermal stability of the duplex by 8-9 degrees C. The irradiation of the ATFMD-containing duplexes by UV light with the wavelength of 350 nm was found to cause the cross-linking reaction of the ATFMD-containing strand with the complementary strand and the formation of the cross-linked duplexes. The photomodification efficiency was independent of the oligonucleotide sequence, with each ATFMD group providing for 5% cross-linking. The irradiation of an ATFMD-containing duplex, a substrate of the HIV-1 integrase, in the presence of this enzyme resulted in the covalent DNA-protein complex. The oligonucleotides with the 1-(4-(3-(trifluoromethyl)-3H-diazirin-3-yl)benzamido)-2,3-propanediol moiety in their chains can be used for the photoaffinity modification of both nucleic acids and proteins that recognize them. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2002, vol. 28, no. 4; see also http://www.maik.ru.

Azirines↗

PubMed2004

Cloning and sequence analysis of the dhaT gene of the 1,3-propanediol regulon from Klebsiella pneumoniae.

1,3-Propanediol oxidoreductase encoded by dhaT gene, a gene of 1,3-propanediol regulon, is important in converting glycerol to 1,3-propanediol in Klebsiella pneumoniae. DhaT gene was amplified from the genome of K. pneumoniae, sequenced and its amino acid sequence deduced. A predicted secondary structure and 3D-structural model was constructed by homology modelling. Based on these results, we infer that 1,3-propanediol oxidoreductase belongs to NAD(P)-dependent alcohol dehydrogenase group III of iron-activated dehydrogenases.

Alcohol Dehydrogenase↗

PubMed1985

Propanediol oxidoreductases of Escherichia coli, Klebsiella pneumoniae and Salmonella typhimurium. Aspects of interspecies structural and regulatory differentiation.

The enzyme propanediol oxidoreductase, which converts the lactaldehyde formed in the metabolism of fucose and rhamnose into propane-1,2-diol under anaerobic conditions, was investigated in Escherichia coli, Klebsiella pneumoniae and Salmonella typhimurium. Structural analysis indicated that the enzymes of E. coli and K. pneumoniae have the same Mr and pI, whereas that of Salm. typhimurium also has the same Mr but a slightly different pI. One-dimensional peptide mapping showed identity between the E. coli and K. pneumoniae enzymes when digested with alpha-chymotrypsin, Staphylococcus aureus V8 proteinase or subtilisin. In the case of Salm. typhimurium, this held only for the subtilisin-digested enzymes, indicating that the hydrophobic regions were preserved to a considerable extent. Anaerobically, the three species induced an active propanediol oxidoreductase when grown on fucose or rhamnose. An inactive propanediol oxidoreductase was induced in Salm. typhimurium by either fucose or rhamnose under aerobic conditions, and this was activated once anaerobiosis was established. An inactive propanediol oxidoreductase was also induced in E. coli under aerobic conditions, but only by growth on fucose. The inactive enzyme was not induced by either of the sugars in K. pneumoniae.

Alcohol Oxidoreductases↗

PubMed1988

Effect of 1,2-propanediol and dimethylsulphoxide on the meiotic spindle of the mouse oocyte.

At ovulation, the mouse oocyte is arrested at metaphase of the second meiotic division. Since microtubules are thermo-and chemosensitive structures, the effects of 1.5 M dimethylsulphoxide and 1.5 M 1,2-propanediol were studied at room temperature on the morphology of the meiotic spindle. Oocytes incubated at 37 degrees C or at room temperature served to estimate the effect of temperature in the experiment. The meiotic spindle was visualized by immunogold-silver staining of microtubules. In the control group at 37 degrees C, 88% of oocytes had normal spindles. After incubation at room temperature for the same time, 89% of oocytes showed abnormal spindles. In the oocytes exposed to dimethyl-sulphoxide or 1,2-propanediol at room temperature a protective effect on spindle morphology could be recognized. Subsequent incubation at 37 degrees C resulted in partial restoration of the observed abnormalities after cooling to room temperature and after exposure to dimethylsulphoxide. Incubation at 37 degrees C after exposure to 1,2-propanediol at room temperature induced spindle absence in the majority of oocytes. Although this latter condition allowed fertilization without increased incidence of ploidy abnormalities, a role for 1,2-propanediol as an activating agent is hypothesized.

Animals↗

PubMed1992

Effects of 1,2-propanediol on the cytoskeletal organization of the mouse oocyte.

The effects of 1,2-propanediol, a cryoprotectant used for the freezing of embryos, were tested on the organization of microtubules and microfilaments in mouse oocytes arrested in metaphase II. At low doses (less than or equal to 1.0 M), 1,2-propanediol induced disorganization of the meiotic spindle but at 1.5 M and higher, it stabilized the spindle. Cytoplasmic asters were observed at all doses tested. An extensive network of free microtubules was observed at 1.0 M and 2.0 M 1,2-propanediol, the former having the stronger disruptive effect on the spindle. Higher doses of 1,2-propanediol (greater than or equal to 1.5 M) caused the oocytes to form cytoplasmic blebs. These blebs lacked detectable cortical microfilaments. In contrast, the microfilament-rich area of the cell cortex overlying the meiotic spindle was not modified.

Actin Cytoskeleton↗

PubMed1984

Microbial metabolism of 1,2-propanediol studied by the Rumen Simulation Technique (Rusitec).

A series of experiments with the Rumen Simulation Technique (Rusitec) showed that 1,2-propanediol was metabolized efficiently by rumen micro-organisms and that the main end-products of fermentation were propionic and 2-methylbutyric acids. Propionaldehyde and n-propanol were also formed as intermediate compounds. The effect of the diol on digestion of the basal diet appeared to be small with concentrate, or when the roughage was supplemented with additional nitrogen (urea). The decrease in the output of acetic and butyric acids was consistent with utilization of C2 units for synthesis of 2-methylbutyric acid. The fermentation of 1,2-propanediol resulted in little or no increase in the output of additional microbial matter. The distribution of radioactivity from [1-14C]1,2-propanediol confirmed that propionaldehyde and n-propanol were the primary products of metabolism of the diol and that the end-products were propionic and 2-methylbutyric acids, with very little labelling of microbial matter. Between 2% and 3% of radioactivity was found in gases and surprisingly the specific radioactivity of methane was higher than that of carbon dioxide, particularly during the initial stages of incubation. Possible pathways in the degradation of 1,2-propanediol by rumen micro-organisms are suggested and discussed in relation to similar reactions established in other systems.

Acyl Coenzyme A↗

PubMed1998

High levels of transcription factor RpoS (sigma S) in mviA mutants negatively affect 1,2-propanediol-dependent transcription of the cob/pdu regulon of Salmonella typhimurium LT2.

Expression of the cobalamin biosynthetic (cob) and 1,2-propanediol utilization (cob/pdu) regulon of Salmonella typhimurium LT2 is controlled at the transcriptional level by global and specific regulatory proteins. In this paper we show that mutations in the mviA gene negatively affect cob/pdu transcription in response to 1,2-propanediol in the environment. The effects of mviA mutations were consistent with its role in the regulation of RpoS levels in the cell. Null mutations in rpoS eliminated the negative effect of mviA mutations on cob/pdu transcription, and restored growth on succinate, propionate and 1,2-propanediol. In addition, mviA mutants were deficient in the utilization of succinate, propionate and 1,2-propanediol as carbon and energy sources.

Amino Acid Sequence↗

PubMed1979

Interactions between 1,2--propanediol (propylene glycol) and hexobarbital.

The interaction between 1,2--propanediol and hexobarbital was studied with an anaesthesia threshold method, where hexobarbital is infused intravenously. The dose needed to obtain a burst suppression of one second or more is determined and given as per cent of a pre-experimental value obtained in the same rat. The effect of varying the interval between the intraperitoneal injection of 1,2--propanediol (2.06 g/kg) and the threshold determination was investigated. In the intervals, 10--50 min., the hexobarbital threshold doses were significantly decreased by 13--27% (n = 7--18). Four different doses between 0.25 and 2.06 g/kg of 1,2--propanediol were then tested after a fixed interval of 30 min. As in the time interval study the thresholds after 2.06 g/kg were significantly decreased. No certain depressant effect was seen with 1.03 and 0.52 g/kg. With the lowest tested dose of 1,2-propanediol (0.25 g/kg) there was instead a significant increase in the threshold dose (13%). This might be an excitatory effect, which could correspond to the well-known effect, seen with low doses of other depressants for instance ethanol.

Animals↗

PubMed1997

The effect of propanediol on the morphology of fresh and frozen equine embryos.

Seventeen horse embryos recovered on the sixth day after spontaneous ovulation were; 1) washed in PBS (n = 6), 2) treated with 1.5 M 1-2 propanediol (n = 6) or, 3) frozen and thawed using 1.5 M propanediol as the cryoprotectant (n = 5). After treatment, the embryos were incubated for 6 h in medium before they were fixed, serially sectioned and examined microscopically to count the total numbers of interphase, mitotic and pycnotic nuclei. Significant differences were measured only in the mean proportions of pycnotic cells (+/- s.d.), both between the control (9.2 +/- 7.3%) and frozen-thawed embryos (52.8 +/- 37.1%; P<0.05) and between the propanediol-treated (10.8 +/- 4.6%) and the frozen-thawed embryos (P<0.01). Propanediol appears to be minimally toxic to equine embryos but it is a poor cryoprotectant.

Animals↗

PubMed1987

Production of 1,3-Propanediol from Glycerol by Clostridium acetobutylicum and Other Clostridium Species.

Glycerol was fermented with the production of 1,3-propanediol as the major fermentation product by four strains of Clostridium acetobutylicum, six of C. butylicum, two of C. beijerinckii, one of C. kainantoi, and three of C. butyricum. 1,3-Propanediol was identified by its retention times in gas chromatography and high-pressure liquid chromatography and by its mass spectrum. During growth of C. butylicum B593 in a chemostat culture at pH 6.5, 61% of the glycerol fermented was converted to 1,3-propanediol. When the pH was decreased to 4.9, growth and 1,3-propanediol production were substantially reduced.

Journal Article↗

PubMed1992

1,3-Propanediol:NAD+ oxidoreductases of Lactobacillus brevis and Lactobacillus buchneri.

In the cofermentation of glycerol with a sugar by Lactobacillus brevis and Lactobacillus buchneri, a 1,3-propanediol:NAD+ oxidoreductase provides an additional method of NADH disposal. The enzyme has been purified from both L. brevis B22 and L. buchneri B190 and found to have properties very similar to those reported for the enzyme from Klebsiella pneumoniae. The enzymes required Mn2+ and are probably octamers with a molecular mass of 350 kDa. Although not absolutely specific for 1,3-propanediol when tested as dehydrogenases, the enzymes have less than 10% activity with glycerol, ethanol, and 1,2-propanediol. These properties contrast sharply with those of a protein isolated from another Lactobacillus species (L. reuteri) that ferments glycerol with glucose and previously designated a 1,3-propanediol dehydrogenase.

Alcohol Dehydrogenase↗

PubMed2006

Microbial conversion of glycerol to 1,3-propanediol: physiological comparison of a natural producer, Clostridium butyricum VPI 3266, and an engineered strain, Clostridium acetobutylicum DG1(pSPD5).

Clostridium acetobutylicum is not able to grow on glycerol as the sole carbon source since it cannot reoxidize the excess of NADH generated by glycerol catabolism. Nevertheless, when the pSPD5 plasmid, carrying the NADH-consuming 1,3-propanediol pathway from C. butyricum VPI 3266, was introduced into C. acetobutylicum DG1, growth on glycerol was achieved, and 1,3-propanediol was produced. In order to compare the physiological behavior of the recombinant C. acetobutylicum DG1(pSPD5) strain with that of the natural 1,3-propanediol producer C. butyricum VPI 3266, both strains were grown in chemostat cultures with glycerol as the sole carbon source. The same "global behavior" was observed for both strains: 1,3-propanediol was the main fermentation product, and the qH2 flux was very low. However, when looking at key intracellular enzyme levels, significant differences were observed. Firstly, the pathway for glycerol oxidation was different: C. butyricum uses a glycerol dehydrogenase and a dihydroxyacetone kinase, while C. acetobutylicum uses a glycerol kinase and a glycerol-3-phosphate dehydrogenase. Secondly, the electron flow is differentially regulated: (i) in C. butyricum VPI 3266, the in vitro hydrogenase activity is 10-fold lower than that in C. acetobutylicum DG1(pSPD5), and (ii) while the ferredoxin-NAD+ reductase activity is high and the NADH-ferredoxin reductase activity is low in C. acetobutylicum DG1(pSPD5), the reverse is observed for C. butyricum VPI 3266. Thirdly, lactate dehydrogenase activity is only detected in the C. acetobutylicum DG1(pSPD5) culture, explaining why this microorganism produces lactate.

Clostridium acetobutylicum↗