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PubMed1980

Methanol monitoring. Comparison of urinary methanol concentration with formic acid excretion rate as a measure of occupational exposure.

Methods of monitoring occupational exposure to methanol were investigated in volunteer subjects who had ingested small amounts of methanol. It was confirmed that urinary methanol concentrations accurately reflected those in the blood. This relationship was maintained over a considerable range of concentrations in spite of large variations of urine flow. Concomitant ingestion of ethanolic beverages increased the urinary methanol concentration slightly. Urinary formic acid concentration was too variable to be of value but rate of urinary excretion of formic acid did reflect methanol uptake. The ratio of urinary formic acid to creatinine concentrations (F/C ratio) is a practical monitoring method. However, formic acid elimination rate is reduced by ingestion of ethanolic beverages. Urinary methanol concentration is favoured as a method of monitoring and a concentration of 10 microgram/ml measured at the end of the work shift is suggested as the level above which occupational exposure should be suspected and the appropriate action taken.

Ethanol↗
PubMedDate not supplied

Methanol and formate kinetics in late diagnosed methanol intoxication.

In a 21-year-old subject, methanol intoxication was undiagnosed for 12 hours after admission. Only bicarbonate treatment was given during this period, although treatment later included ethanol and haemodialysis. The maximal blood methanol and formate levels were 143 (44.7) and 54.3 mg/dl (11.8 mmol/L), respectively. The delayed diagnosis uniquely allowed for an estimate of methanol elimination kinetics. Before specific treatment, methanol elimination was of zero-order, with a rate of 8.5 mg/dl/h. After admission, the formate levels remained relatively constant until blood pH was normalised by bicarbonate treatment. From this point the formate levels declined, despite an unchanged methanol elimination, indicating that the formate was eliminated faster than it was formed from methanol. Thus, formate elimination may be pH-dependent and aggressive treatment of the acidosis may increase this elimination.

Adult↗
PubMed1998

Combined toxicity of methanol and formic acid: two cases of methanol poisoning.

Two fatalities caused by methanol ingestion are presented. Quantitative analysis of methanol and formic acid using head-space gas chromatography showed concentrations of methanol and formic acid in the femoral blood of each subject of 2.19 mg/ml and 0.41 mg/ml, and 1.96 mg/ml and 0.38 mg/ml, respectively. We concluded that death was due to methanol ingestion and the mechanism causing death involved the combined effects of the anesthetic action of methanol itself and metabolic acidosis by formic acid. Forensic toxicokinetic analysis indicated that both victims had ingested about 100 g of methanol or more.

Adult↗
PubMed2006

Insight into the mechanism of biological methanol activation based on the crystal structure of the methanol-cobalamin methyltransferase complex.

Some methanogenic and acetogenic microorganisms have the catalytic capability to cleave heterolytically the C O bond of methanol. To obtain insight into the elusive enzymatic mechanism of this challenging chemical reaction we have investigated the methanol-activating MtaBC complex from Methanosarcina barkeri composed of the zinc-containing MtaB and the 5-hydroxybenzimidazolylcobamide-carrying MtaC subunits. Here we report the 2.5-A crystal structure of this complex organized as a (MtaBC)(2) heterotetramer. MtaB folds as a TIM barrel and contains a novel zinc-binding motif. Zinc(II) lies at the bottom of a funnel formed at the C-terminal beta-barrel end and ligates to two cysteinyl sulfurs (Cys-220 and Cys-269) and one carboxylate oxygen (Glu-164). MtaC is structurally related to the cobalamin-binding domain of methionine synthase. Its corrinoid cofactor at the top of the Rossmann domain reaches deeply into the funnel of MtaB, defining a region between zinc(II) and the corrinoid cobalt that must be the binding site for methanol. The active site geometry supports a S(N)2 reaction mechanism, in which the C O bond in methanol is activated by the strong electrophile zinc(II) and cleaved because of an attack of the supernucleophile cob(I)amide. The environment of zinc(II) is characterized by an acidic cluster that increases the charge density on the zinc(II), polarizes methanol, and disfavors deprotonation of the methanol hydroxyl group. Implications of the MtaBC structure for the second step of the reaction, in which the methyl group is transferred to coenzyme M, are discussed.

Binding Sites↗
PubMed1980

Distribution of methanol carbon between assimilation and oxidation pathways in methanol-grown Pseudomonas C.

In Pseudomonas C, a facultative methylotrophic bacterium, methanol is assimilated via the 2-keto-3-deoxy-6-phosphogluconate (KDPG) variant of the ribulose monophosphate (RMP) pathway of formaldehyde fixation. The oxidation of methanol to CO2 is accomplished by the direct oxidation pathway (which involves formic acid as an oxidation intermediate), via a cyclic oxidation pathway (glucose monophosphate shunt) and by other decarboxylation reactions. The distribution pattern of methanol carbon among the assimilation and the different oxidation pathways was studied by measuring the distribution between CO2 and cell constituents of 14C-labelled compounds after their injection into a culture growing on methanol in a chemostat. From these measurements, it was calculated that 25% of the methanol consumed by the cells was oxidized through formate to CO2, while the remainder was diverted into the hexulosephosphate synthase reaction from which 55% was assimilated through the KDPG reaction and 17% was oxidized to CO2 via a cyclic oxidation pathway and other decarboxylation reactions. The remaining 7% from the methanol carbon was re-incorporated as CO2 into cell material through carboxylation reactions.

Carbon Dioxide↗
PubMed1975

Oxidation of C1 compounds by particulate fractions from Methylococcus capsulatus: properties of methanol oxidase and methanol dehydrogenase.

Methanol (and formaldehyde) oxidizing activities in crude extracts of Methylococcus capsulatus are associated mainly with particulate fractions sedimenting between 3,000 and 40,000 X g. Most of the phenazine methosulfate (PMS)-dependent methanol (and formaldehyde) dehydrogenase activity observed resides in the soluble fraction but represents only 40% of the total (PMS dependent plus independent) activity. Both PMS-dependent methanol dehydrogenase activity and PMS-independent methanol oxidase activity are found in particulate fractions, and the PMS-dependent dehydrogenase is easily solubilized by treatment with certain phospholipases or detergents. The properties of the PMS-dependent dehydrogenase activities in the soluble fraction and that solubilized from the particles suggested that they may be identical proteins. Their pH optima, temperature dependence, thermolabilities, and sensitivities to the presence of specific antisera were indistinguishable. Homogeneous preparations of the enzyme proteins obtained from the soluble fractions of extracts and the particulate fractions solubilized by detergents had similar: (i) electrophoretic mobilities in native and denatured states (subunit size in sodium dodecyl sulfate 62,000 daltons); (ii) molecular radii under native conditions, (iii) visible absorption spectra, lambdamax 350 nm, (iv) kinetic constants for methanol and formaldehyde; (v) substrate specificity; and (vi) immunological characteristics--antisera to each enzyme preparation showed precipitin lines of identity to either of the enzymes. It is suggested that the major site of methanol and formaldehyde oxidation in M. capsulatus occurs on the intracytoplasmic membranes in vivo and is coupled to oxygen reduction.

Alcohol Oxidoreductases↗
PubMed1986

Isolation and complementation analysis of 10 methanol oxidation mutant classes and identification of the methanol dehydrogenase structural gene of Methylobacterium sp. strain AM1.

A method has been developed for the direct selection of methanol oxidation mutants of the facultative methylotroph Methylobacterium sp. strain AM1 (formerly Pseudomonas sp. strain AM1). Using this direct selection technique, we have isolated mutants of Methylobacterium sp. strain AM1 that are no longer capable of growth on methanol but retain the ability to grow on methylamine. These methanol oxidation (Mox) mutants were complemented with a genomic clone bank of this organism constructed in the broad-host-range cosmid pVK100, and subcloning and Tn5 mutagenesis experiments have assigned the Mox mutants to 10 distinct complementation groups. Using an open reading frame beta-galactosidase fusion vector and antibodies specific for Methylobacterium sp. strain AM1 methanol dehydrogenase, we have identified the methanol dehydrogenase structural gene and determined the direction of transcription. The results suggest that the synthesis and utilization of an active methanol dehydrogenase in this organism requires at least 10 different gene functions.

1-Propanol↗
PubMed1995

Definitive identification of an exceptionally high methanol concentration in an intoxication of a surviving infant: methanol metabolism by first-order elimination kinetics.

Intoxication by methanol was identified in a five-week-old infant suffering from moderate metabolic acidosis. The initial serum methanol at admission was 1148 mg/dL as measured by gas chromatography. The osmolal gap and formic acid concentrations were consistent with methanol intoxication. The child was treated with folic acid and a continuous ethanol infusion and survived without any apparent permanent problems. Because expected toxic symptoms did not develop in this case, and the methanol concentrations were at levels that might be deemed to be incompatible with life, blood and urine samples were assayed by a specific enzymatic assay, and by gas chromatography/mass spectrometry (GC/MS). Positive results definitively confirmed the presence of methanol. In contrast to previous reports, the elimination of methanol in this case appeared to following first-order kinetics. If hepatic ADH activity is low in neonates and young infants, another enzyme system such as catalase may be involved to explain this data. The lack of formic acid accumulation may have been due to folic acid therapy.

Acidosis↗
PubMed1993

[Methanol level and methanol elimination in alcoholic patients].

A total of 54 male alcoholics aged between 26 and 57 years who had been admitted in an intoxicated state to a psychiatric hospital for acute care and subsequent detoxification were included in the study. The blood ethanol concentration (BEC) and serum methanol concentration (SMC) at the time of admission (n = 49) and the methanol elimination curve during ethanol elimination (n = 19) and after the ethanol concentration had fallen to zero (n = 4) were investigated. On admission, the BEC ranged from 0.21 g/kg to 3.26 g/kg and the SMC ranged from 5 mg/kg to 44 mg/kg. The gamma-alcoholics (n = 28) exhibited higher ethanol concentrations than the delta-alcoholics (n = 11) but no difference was found in the methanol concentrations. The methanol level was found to be related to the ethanol level in gamma-alcoholics (r = 0.671; p < 0.001), but not in d-alcoholics (r = 0.215; p > 0.05). The methanol content of the most recently consumed and generally preferred type of alcoholic beverage was found to influence the SMC in all the alcoholics. The SMC did not fall during ethanol oxidation (BEC > 0.2g/kg). After the ethanol concentration had fallen to zero, methanol elimination was found to follow first order kinetics; the elimination constants ranged from 0.592 h-1 to 0.209 h-1, corresponding to elimination half-life values of 1.2 h to 3.3 h. No differences were found between these values and those of non-alcoholic subjects.

Adult↗
PubMed2005

A Kirkwood-Buff derived force field for methanol and aqueous methanol solutions.

A force field for the simulation of methanol and aqueous methanol mixtures is presented. The force field was specifically designed to reproduce the experimental Kirkwood-Buff integrals as a function of methanol mole fraction, thereby ensuring a reasonable description of the methanol cosolvent and water solvent activities. Other thermodynamic and physical properties of pure methanol and aqueous methanol solutions, including the density, enthalpy of mixing, translational diffusion constants, compressibility, thermal expansion, and dielectric properties, were also well reproduced.

Journal Article↗
PubMed2006

Methanol utilizing Desulfotomaculum species utilizes hydrogen in a methanol-fed sulfate-reducing bioreactor.

A sulfate-reducing bacterium, strain WW1, was isolated from a thermophilic bioreactor operated at 65 degrees C with methanol as sole energy source in the presence of sulfate. Growth of strain WW1 on methanol or acetate was inhibited at a sulfide concentration of 200 mg l(-1), while on H2/CO2, no apparent inhibition occurred up to a concentration of 500 mg l(-1). When strain WW1 was co-cultured under the same conditions with the methanol-utilizing, non-sulfate-reducing bacteria, Thermotoga lettingae and Moorella mulderi, both originating from the same bioreactor, growth and sulfide formation were observed up to 430 mg l(-1). These results indicated that in the co-cultures, a major part of the electron flow was directed from methanol via H2/CO2 to the reduction of sulfate to sulfide. Besides methanol, acetate, and hydrogen, strain WW1 was also able to use formate, malate, fumarate, propionate, succinate, butyrate, ethanol, propanol, butanol, isobutanol, with concomitant reduction of sulfate to sulfide. In the absence of sulfate, strain WW1 grew only on pyruvate and lactate. On the basis of 16S rRNA analysis, strain WW1 was most closely related to Desulfotomaculum thermocisternum and Desulfotomaculum australicum. However, physiological properties of strain WW1 differed in some aspects from those of the two related bacteria.

Acetic Acid↗
PubMed2004

Thermophilic (55 degrees C) conversion of methanol in methanogenic-UASB reactors: influence of sulphate on methanol degradation and competition.

Two upflow sludge bed reactors (UASB) were operated for 80 days at 55 degrees C with methanol as the substrate with an organic loading rate (OLR) of about 20 g CODl(-1) per day and a hydraulic retention time (HRT) of 10 h. One UASB was operated without sulphate addition (control reactor-R1) whereas the second was fed with sulphate at a COD:SO4(2-) ratio of 10 (sulphate-fed reactor-R2), providing an influent sulphate concentration of 0.6 g l(-1). For both reactors, methanogenesis was the dominant process with no considerable accumulation of acetate. The methanol removal averaged 93% and 83% for R1 and R2, respectively, and total sulphate removal was achieved in the latter. The pathway of methanol conversion for both sludges was investigated by measuring the fate of carbon in the presence and absence of bicarbonate or specific inhibitors for a sludge sample collected at day 72. In both sludges, about 70% of the methanol was syntrophically converted to methane and/or sulphide, via the intermediate H2/CO2. A strong competition between methanogens and sulphidogens took place in the R2 sludge with half of the methanol-COD being used by methane-producing bacteria and the other half by sulphate-reducing bacteria. Acetate was not an important intermediate for both sludges, and played a slightly more important role for the sulphate-adapted sludge (R2), sustained by the higher amount of bicarbonate produced during sulphate-reduction. The pathway study indicates that, although acetate does not represent an important intermediate, the system is susceptible to its accumulation.

Archaea↗
PubMed2000

Growth of Candida boidinii on methanol and the activity of methanol-degrading enzymes as affected from formaldehyde and methylformate.

Formaldehyde and methylformate affect the growth of Candida boidinii on methanol and the activity of methanol-degrading enzymes. The presence of both intermediates in the feeding medium caused an increase in biomass yield and productivity and a decrease in the specific rate of methanol consumption. In the presence of formaldehyde, the activity of formaldehyde dehydrogenase and formate dehydrogenase was essentially increased, whereas the activity of methanol oxidase was decreased. On the contrary, the presence of methylformate caused an increase of the activity of methanol oxidase and a decrease of the activity of formaldehyde dehydrogenase and formate dehydrogenase. Interpretations concerning the yeast behavior in the presence of intermediate oxidation products were considered and discussed.

Alcohol Oxidoreductases↗
PubMed1995

Methanol half-life during ethanol administration: implications for management of methanol poisoning.

STUDY OBJECTIVE: To determine the half-life of methanol in methanol-poisoned patients who are treated with ethanol but not with hemodialysis. DESIGN: Case series. SETTING: University Hospital, University of Manitoba. PARTICIPANTS: Three methanol-poisoned patients treated with ethanol but not with hemodialysis and three similar patients identified by a literature review. RESULTS: Plots of terminal concentration versus time data were inconsistent with zero-order kinetics and were adequately explained by an apparent first-order process. The median half-life of methanol in these patients was 43.1 hours, with a range of 30.3 to 52.0 hours. CONCLUSION: Because of the significantly increased risk of toxicity and complications during ethanol monotherapy, we suggest that hemodialysis be considered for methanol-poisoned patients who are treated with ethanol infusion.

Adult↗
PubMed2006

Molecular interaction between Methylobacterium extorquens and seedlings: growth promotion, methanol consumption, and localization of the methanol emission site.

Four Methylobacterium extorquens strains were isolated from strawberry (Fragaria x ananassa cv. Elsanta) leaves, and one strain, called ME4, was tested for its ability to promote the growth of various plant seedlings. Seedling weight and shoot length of Nicotiana tabacum, Lycopersicon esculentum, Sinapis alba, and Fragaria vesca increased significantly in the presence of the pink-pigmented facultative methylotroph (PPFM), but the germination behaviour of seeds from six other plants was not affected. The cell-free supernatant of the bacterial culture stimulated germination, suggesting the production of a growth-promoting agent by the methylotroph. Methanol emitted from N. tabacum seedlings, as determined by proton-transfer-reaction mass spectrometry (PTR-MS), ranged from 0.4 to 0.7 ppbv (parts per billion by volume), while significantly lower levels (0.005 to 0.01 ppbv) of the volatile alcohol were measured when the seedlings were co-cultivated with M. extorquens ME4, demonstrating the consumption of the gaseous methanol by the bacteria. Additionally, by using cells of the methylotrophic yeast Pichia pastoris transformed with the pPICHS/GFP vector harbouring a methanol-sensitive promoter in combination with the green fluorescence protein (GFP) reporter gene, stomata were identified as the main source of the methanol emission on tobacco cotyledons. Methylobacterium extorquens strains can nourish themselves using the methanol released by the stomata and release an agent promoting the growth of the seedlings of some crop plants.

Cotyledon↗
PubMed1976

Microbial oxidation of methane and methanol: crystallization and properties of methanol dehydrogenase from Methylosinus sporium.

Obligate methylotrophs are divisible into two types on the basis of ultrastructural biochemical characteristics. Both groups possess a soluble phenazine methosulfate (PMS)-dependent methanol dehydrogenase. In addition, particulate PMS-dependent methanol dehydrogenase and PMS-independent methanol oxidase have been found in the type I membrane group. A procedure was developed for the crystallization of methanol dehydrogenase from the soluble fraction of the type II obligate methylotroph Methylosinus sporium. This is the first report of a crystalline methanol dehydrogenase from a methylotrophic bacterium. The crystallized enzyme is homogeneous as judged by ultracentrifugation and by acrylamide gel electrophoresis. In the presence of an electron acceptor (phenazine or phenazinium compound) and an activator (ammonium compound), the crystallized enzyme catalyzed the oxidation of primary alcohols and formaldehyde. Secondary, tertiary, and aromatic alcohols were not oxidized. The molecular weight of the enzyme as estimated by gel filtration is approximately 60,000, and as estimated by sedimentation equilibrium analysis it is 62,000. The sedimentation constant (S20,W) is 2.9. The subunit size determined by sodium dodecyl sulfate-gel electrophoresis is approximately 60,000. The amino acid composition and spectral properties of the enzyme are also presented. Antisera prepared against the crystalline enzyme are nonspecific, they cross-reacted and inhibited isofunctional enzymes from other obligate methylotrophic bacteria.

Alcohol Oxidoreductases↗
PubMed1993

The use of trehalose-stabilized lyophilized methanol dehydrogenase from Hyphomicrobium X for the detection of methanol.

The enzyme methanol dehydrogenase (EC 1.1.99.8) from Hyphomicrobium X was used in an attempt to develop a rapid colorimetric test for methanol. The enzyme was stabilized for storage by lyophilization in the presence of the disaccharide trehalose. It was found that the enzyme retained significantly greater activity in the dried state with trehalose than without. The enzyme was partially purified by ammonium sulphate fractionation, after which it was found to be more stable in solution at pH 9 than at pH 7. A procedure is given which involves mixing a defined amount of enzyme with the methanol-containing water together with phenazine methosulphate (PMS), 2-6-dichlorophenol-indophenol (DCPIP) and cyanide, and observing the resultant colour change from blue to yellow if methanol is present. The sensitivity of the procedure is such that 9 mg L-1 of methanol can be readily detected.

2,6-Dichloroindophenol↗
PubMed2005

Site-site memory equation approach in study of density/pressure dependence of translational diffusion coefficient and rotational relaxation time of polar molecular solutions: acetonitrile in water, methanol in water, and methanol in acetonitrile.

We present results of the theoretical study and numerical calculation of the dynamics of molecular liquids based on the combination of the memory equation formalism and the reference interaction site model (RISM). Memory equations for the site-site intermediate scattering functions are studied in the mode-coupling approximation for the first-order memory kernels, while equilibrium properties such as site-site static structure factors are deduced from RISM. The results include the temperature-density (pressure) dependence of translational diffusion coefficients D and orientational relaxation times tau for acetonitrile in water, methanol in water, and methanol in acetonitrile--all in the limit of infinite dilution. Calculations are performed over the range of temperatures and densities employing the extended simple point charge model for water and optimized site-site potentials for acetonitrile and methanol. The theory is able to reproduce qualitatively all main features of temperature and density dependences of D and tau observed in real and computer experiments. In particular, anomalous behavior, i.e, the increase in mobility with density, is observed for D and tau of methanol in water, while acetonitrile in water and methanol in acetonitrile do not show deviations from the ordinary behavior. The variety exhibited by the different solute-solvent systems in the density dependence of the mobility is interpreted in terms of the two competing origins of friction, which interplay with each other as density increases: the collisional and dielectric frictions which, respectively, increase and decrease with increasing density.

Journal Article↗