Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Methanol”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1995

Methanol Emission from Leaves (Enzymatic Detection of Gas-Phase Methanol and Relation of Methanol Fluxes to Stomatal Conductance and Leaf Development).

We recently reported the detection of methanol emissions from leaves (R. MacDonald, R. Fall [1993] Atmos Environ 27A: 1709-1713). This could represent a substantial flux of methanol to the atmosphere. Leaf methanol production and emission have not been investigated in detail, in part because of difficulties in sampling and analyzing methanol. In this study we used an enzymatic method to convert methanol to a fluorescent product and verified that leaves from several species emit methanol. Methanol was emitted almost exclusively from the abaxial surfaces of hypostomatous leaves but from both surfaces of amphistomatous leaves, suggesting that methanol exits leaves via stomates. The role of stomatal conductance was verified in experiments in which stomates were induced to close, resulting in reduced methanol. Free methanol was detected in bean leaf extracts, ranging from 26.8 [mu]g g-1 fresh weight in young leaves to 10.0 [mu]g g-1 fresh weight in older leaves. Methanol emission was related to leaf development, generally declining with increasing leaf age after leaf expansion; this is consistent with volatilization from a cellular pool that declines in older leaves. It is possible that leaf emission could be a major source of methanol found in the atmosphere of forests.

Journal Article↗
PubMed1976

Growth of Hansenula polymorpha in a methanol-limited chemostat. Physiological responses due to the involvement of methanol oxidase as a key enzyme in methanol metabolism.

Hansenula polymorpha has been grown in a methanol-limited continuous culture at a variety of dilution rates. Cell suspensions of the yeast grown at a dilution rate of 0.16 h-1 showed a maximal capacity to oxidize excess methanol (QmaxO2) which was 1.6 times higher than the rate required to sustain the growth rate (QO2). When the dilution rate was decreased to 0.03 h-1, QmaxO2 of cells increased to a value of more than 20 times that of QO2. The enzymatic basis for this tremendous overcapacity for the oxidation of excess methanol at low growth rates was found to be the methanol oxidase content of the cells. The level of this enzyme increased from 7% to approximately 20% of the soluble protein when the growth rate was decreased from 0.16 to 0.03 h-1. These results were explained on the basis of the poor affinity of methanol oxidase for its substrates. Methanol oxidase purified from Hansenula polymorpha showed an apparent Km for methanol of 1.3 mM in air saturated reaction mixtures and the apparent Km of the enzyme for oxygen was 0.4 mM at a methanol concentration of 100 mM. The involvement of an oxygen dependent methanol oxidase in the dissimilation of methanol in Hansenula polymprpha was also reflected in the growth yield of the organism. The maximal yield of the yeast was found to be low (0.38 g cells/g methanol). This was not due to a very high maintenance energy requirement which was estimated to be 17 mg methanol/g cells X h.

Alcohol Oxidoreductases↗
PubMed1985

Mechanism of action of methanol oxidase, reconstitution of methanol oxidase with 5-deazaflavin, and inactivation of methanol oxidase by cyclopropanol.

Methanol oxidase isolated from Hansenula polymorpha contains two distinct flavin cofactors in approximately equal amounts. One has been identified as authentic FAD and the other as a modified form of FAD differing only in the ribityl portion of the ribityldiphosphoadenosine side chain. The significance of this finding is as yet unknown. Previous studies have shown that cyclopropanol irreversibly inactivates methanol oxidase [Mincey, T., Tayrien, G., Mildvan, A. S., & Abeles, R. H. (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 7099-7101]. We have now established that inactivation is accompanied by covalent modification of the flavin cofactor. The stoichiometry of this reaction is 1 mol of cyclopropanol/mol of active flavin. The structure of the covalent adduct was determined by NMR, IR, and UV spectral studies to be an N5,C4a-cyclic 4a,5-dihydroflavin. Reduction of the covalent adduct with NaBH4 at pH 9.0 before removal from the enzyme converted it to the 1-(ribityldiphosphoadenosine)-substituted 4-(3-hydroxypropyl)-2,3-dioxoquinoxaline. Cyclopropyl ring cleavage accompanies inactivation, and covalent bond formation occurs between a methylene carbon of cyclopropanol and N5 of flavin. Methanol oxidase was also reconstituted with 5-deazaflavin adenine dinucleotide (dFAD). Reconstituted enzyme did not catalyze the oxidation of alcohols to the corresponding aldehydes, nor did reduced reconstituted enzyme catalyze the reverse reaction. Incubation of reconstituted enzyme with cyclopropanol resulted in an absorbance decrease at 399 nm, but no irreversible covalent modification of the deazaflavin cofactor. A reversible addition complex between cyclopropanol and dFAD is formed. The structure of that complex was not definitively established, but it is likely that it is formed through the addition of cyclopropoxide to C5 of dFAD. The failure of dFAD-reconstituted methanol oxidase to catalyze the oxidation of substrate, as well as the lack of reaction with cyclopropanol, supports a radical mechanism for alcohol oxidation and cyclopropanol inactivation. Methanol oxidase catalyzes the oxidation of cyclopropylcarbinol to the corresponding aldehyde. No ring-opened products were detected. The failure to form ring-opened products has been used as an argument against radical processes [MacInnes, I., Nonhebel, D. C., Orsculik, S. T., & Suckling, C. J. (1982) J. Chem. Soc., Chem. Commun., 121-122]. We present arguments against this interpretation.

Alcohol Oxidoreductases↗
PubMed1997

Pharmacokinetics of methanol and formate in female cynomolgus monkeys exposed to methanol vapors.

The 1990 Clean Air Act Amendments contain mandates for reduced automotive emissions and add new requirements for the use of alternative fuels such as methanol to reduce certain automotive pollutants. Methanol is acutely toxic in humans at relatively low doses, and the potential for exposure to methanol will be increased if it is used in automotive fuel. Formate is the metabolite responsible for neurotoxic effects of acute methanol exposure. Since formate metabolism is dependent on folate, potentially sensitive folate-deficient subpopulations, such as pregnant women, may accumulate formate and be at higher risk from low-level methanol exposure. Our objective was to determine the pharmacokinetics of 14C-methanol and 14C-formate in normal and folate-deficient monkeys after exposure to 14C-methanol vapors at environmentally relevant concentrations: below the threshold limit value (TLV), at the TLV of 200 parts per million (ppm), and above the TLV. Four normal adult female cynomolgus monkeys were individually anesthetized with isoflurane, and each was exposed by endotracheal intubation to 10, 45, 200, or 900 ppm 14C-methanol for 2 hours. Concentrations of the inhaled and exhaled 14C-methanol, blood concentrations of 14C-methanol and 14C-formate, exhaled 14C-carbon dioxide (14CO2), and respiratory parameters were measured during exposure. After exposure, 14C-methanol and 14CO2 exhaled, 14C-methanol and 14C-formate excreted in urine, and 14C-methanol and 14C-formate in blood were quantified. The amounts of exhaled 14C-methanol and 14CO2, blood concentrations of 14C-methanol and 14C-formate, and 14C-methanol and 14C-formate excreted in urine were linearly related to methanol exposure concentration. For all exposures, blood concentrations of 14C-methanol-derived formate were 10 to 1000 times lower than endogenous blood formate concentrations (100 to 200 mM) reported for monkeys and were several orders of magnitude lower than levels of formate known to be toxic. Since the metabolism of formate in primates depends on the availability of tetrahydrofolate, the same four monkeys were next placed on a folate-deficient diet until folate concentrations in red blood cells consistent with moderate folate deficiency (29 to 107 ng/mL) were achieved. Monkeys were then reexposed to the highest exposure concentration, 900 ppm 14C-methanol, for a similar 2-hour period, and again the pharmacokinetic data described above were obtained. Even with a reduced folate status, monkeys exposed to 900 ppm methanol for 2 hours had peak concentrations of methanol-derived formate that were well below the endogenous levels of formate. Although these results represent only a single exposure and therefore preclude broad generalizations, they do suggest the body contains sufficient folate stores to effectively detoxify small doses of methanol-derived formate from exogenous sources, such as those that might occur during normal use of automotive fuel.

Adult↗
PubMedDate not supplied

A pharmacokinetic model of inhaled methanol in humans and comparison to methanol disposition in mice and rats.

We estimated kinetic parameters associated with methanol disposition in humans from data reported in the literature. Michaelis-Menten elimination parameters (Vmax = 115 mg/L/hr; Km = 460 mg/L) were selected for input into a semi-physiologic pharmacokinetic model. We used reported literature values for blood or urine methanol concentrations in humans and nonhuman primates after methanol inhalation as input to an inhalation disposition model that evaluated the absorption of methanol, expressed as the fraction of inhaled methanol concentration that was absorbed (phi). Values of phi for nonexercising subjects typically varied between 0.64 and 0.75; 0.80 was observed to be a reasonable upper boundary for fractional absorption. Absorption efficiency in exercising subjects was lower than that in resting individuals. Incorporation of the kinetic parameters and phi into a pharmacokinetic model of human exposure to methanol, compared to a similar analysis in rodents, indicated that following an 8-hr exposure to 5000 ppm of methanol vapor, blood methanol concentrations in the mouse would be 13- to 18-fold higher than in humans exposed to the same methanol vapor concentration; blood methanol concentrations in the rat under similar conditions would be 5-fold higher than in humans. These results demonstrate the importance in the risk assessment for methanol of basing extrapolations from rodents to humans on actual blood concentrations rather than on methanol vapor exposure concentrations.

Animals↗
PubMed2006

Upregulated transcription of plasmid and chromosomal ribulose monophosphate pathway genes is critical for methanol assimilation rate and methanol tolerance in the methylotrophic bacterium Bacillus methanolicus.

The natural plasmid pBM19 carries the key mdh gene needed for the oxidation of methanol into formaldehyde by Bacillus methanolicus. Five more genes, glpX, fba, tkt, pfk, and rpe, with deduced roles in the cell primary metabolism, are also located on this plasmid. By using real-time PCR, we show that they are transcriptionally upregulated (6- to 40-fold) in cells utilizing methanol; a similar induction was shown for two chromosomal genes, hps and phi. These seven genes are involved in the fructose bisphosphate aldolase/sedoheptulose bisphosphatase variant of the ribulose monophosphate (RuMP) pathway for formaldehyde assimilation. Curing of pBM19 causes higher methanol tolerance and reduced formaldehyde tolerance, and the methanol tolerance is reversed to wild-type levels by reintroducing mdh. Thus, the RuMP pathway is needed to detoxify the formaldehyde produced by the methanol dehydrogenase-mediated conversion of methanol, and the in vivo transcription levels of mdh and the RuMP pathway genes reflect the methanol tolerance level of the cells. The transcriptional inducer of hps and phi genes is formaldehyde, and not methanol, and introduction of multiple copies of these two genes into B. methanolicus made the cells more tolerant of growth on high methanol concentrations. The recombinant strain also had a significantly higher specific growth rate on methanol than the wild type. While pBM19 is critical for growth on methanol and important for formaldehyde detoxification, the maintenance of this plasmid represents a burden for B. methanolicus when growing on mannitol. Our data contribute to a new and fundamental understanding of the regulation of B. methanolicus methylotrophy.

Alcohol Oxidoreductases↗
PubMed1991

Methanol in urine as a biological indicator of occupational exposure to methanol vapor.

The exposure-excretion relationship and possible health effects of exposure to methanol vapor were studied in 33 exposed workers during the second half of 2 working weeks. Urinary methanol concentrations were also determined in 91 nonexposed subjects. The geometric mean value for methanol in urine samples from the latter was less than 2 mg/l (95% upper limit of normal, less than 5 mg/l) when log-normal distribution was assumed. Among the exposed workers, the methanol level in urine samples collected prior to the work shift exceeded the 95% upper limit of normal. The time-weighted average intensity of exposure to methanol vapor was measured using personal sampling devices (in which water severed as an absorbent) in 48 cases of methanol exposure (i.e., 2 of the 33 exposed workers failed to provide urine samples, whereas 17 subjects were examined twice). Methanol concentrations in urine were determined in samples collected at the end of the shift from the 48 exposed cases as well as from 30 nonexposed controls. There was a significant correlation between the exposure to methanol vapor at concentrations of up to 5,500 ppm and the levels of methanol measured in the shift-end urine samples. The calculation indicated that a mean level of 42 mg methanol/l urine (95% confidence range, 26-60 mg/kg) was excreted in the shift-end urine sample following 8 h exposure to methanol at 200 ppm (the current occupational exposure limit). Dimmed vision and nasal irritation were among the most frequent symptoms complained during work. Three cases showing clinical signs of borderline significance were identified.

Adult↗
PubMed2006

Bioconversion of methanol to formaldehyde. II. By purified methanol oxidase from modified yeast, Hansenula polymorpha.

Modified methylotrophic yeast Hansenula polymorpha (HP A16) that was obtained by repressing leucine oxotrophic yeast; a wild type of Hansenula polymorpha CB4732 was used in this study. The yeast is grown with methanol, which is used as a sole carbon source, using various methanol concentrations and temperatures, and methanol oxidase (MOX) which is a key enzyme of methanol metabolism; production is maximized. Whole yeast cells were cultivated under optimized inoculation conditions; they were separated into two portions. One portion of these cells was directly used in bioconversion of methanol to formaldehyde. The second portion of the free cells was broken into pieces and a crude enzyme extract was obtained. The MOX enzyme in this extract was purified via salt precipitation, dialysis, and chromatographic methods. The purified MOX enzyme of yeast (HP A16) oxidized the methanol to formaldehyde. Optimization of bioconversion conditions was studied to reach maximum activity of enzyme. The optimum temperature and pH were found to be 35 degrees C and pH 8.0 in boric acid/NaOH buffer, and it was stable over the pH range of 6-9, at the 20 degrees C 15 min. A suitable reaction period was found as 50 min. The enzyme indicated low carbon primary alcohols (C2 to C4), as well as methanol. Initially, MOX activity increased with the increase of methanol concentration, but enzyme activity decreased. The apparent Km and Vmax values for methanol substrate of HP A16 MOX were 0.25 mM and 30 U/mg, respectively. The purified MOX enzyme was applied onto sodium dodecyl sulphate-polyacrylamide gel electrophoresis; molecular weight of the enzyme was calculated to be about 670 kDa. Each MOX enzyme is composed of eight identical subunits, each of whose molecular weight is around 82 kDa and which contain eight moles of FAD as the prosthetic group, and the pI of the natural enzyme is found to be 6.4. The purified MOX enzyme was used in the bioconversion of methanol to formaldehyde as a catalyst; this conversion was compared to the conversion percentages of whole cells in our previous article in terms of catalytic performances.

Alcohol Oxidoreductases↗
PubMed1990

Enzymatic assay of formic acid and gas chromatography of methanol for urinary biological monitoring of exposure to methanol.

An enzymatic assay method for the determination of urinary formic acid is described. Formic acid in urine was cleaved to carbon dioxide and water by formic acid dehydrogenase, whereby NAD+ was converted to NADH, which reacted with INT (p-iodonitrotetrazolium violet) in the presence of NAD-diaphorase. The color thus produced was determined at 500 nm. In addition, a simple gas chromatographic method of urinary formic acid is described, in which head space gas of formic acid methylester was applied into the wide bore column. The urinary formic acid concentrations by the enzymatic method agreed well with that by the gas chromatographic method. A simple gas chromatographic method for urinary methanol assay is also described. Acetonitrile was added to an equal volume of urine containing methanol. After centrifugation, the supernatant was injected into gas chromatography (GC). The peaks of urinary methanol and ethanol were separated by GC. Formic acid and methanol in urine of unexposed healthy subjects and workers exposed to methanol were analyzed by the colorimetric and gas chromatographic methods. Geometric mean concentrations of urinary formic acid and methanol in the healthy subjects were 7.82 mg/g creatinine and 1.34 mg/l, respectively. The concentration ratio of formic acid to methanol in the urine of the workers exposed to methanol was calculated to be 3.67 +/- 2.10, which agreed with the ratio under a controlled exposure experiment. A slower excretion of formic acid than that of methanol in the urine of a volunteer was also observed.

Adult↗
PubMed1992

Formic acid excretion in comparison with methanol excretion in urine of workers occupationally exposed to methanol.

A semiautomated head-space gas chromatographic (GC) method was developed for measuring formic acid in urine. The method consists of heating 1 ml urine sample in a 20-ml air-tight vial in the presence of 1 ml sulfuric acid and 2 ml ethanol at 60 degrees C for 30 min for ethyl esterification and air-liquid equilibrium, followed by automatic injection of 1 ml head-space air into a flame ionization detector GC. The detection limit was 1 mg/l for formic acid. The method was applied to measure formic acid in the shift-end urine samples from 88 workers exposed to methanol at 66.6 ppm (as geometric mean) and in urine samples from 149 nonexposed controls. Methanol concentrations were also determined. Regression analysis showed that urinary formic acid concentrations, as observed or corrected for either creatinine concentration or specific gravity of urine (1.016), correlated significantly with time-weighted average intensities of exposure to methanol vapor. Men excreted significantly more formic acid than women. Comparison with methanol excretion suggested, however, that urinary formic acid is less sensitive than urinary methanol as an indicator of methanol vapor exposure, primarily because the background level for formic acid (26 mg/l as arithmetic mean, or 23 mg/l as geometric mean) is more than ten times higher than the level for methanol (1.9 mg/l as arithmetic mean, or 1.7 mg/l as geometric mean). After theoretical methanol exposure at infinite concentration, the urinary formic acid/methanol ratio should be about 0.4.

Adult↗
PubMed1989

Methanol metabolism in thermotolerant methylotrophic Bacillus strains involving a novel catabolic NAD-dependent methanol dehydrogenase as a key enzyme.

The enzymology of methanol utilization in thermotolerant methylotrophic Bacillus strains was investigated. In all strains an immunologically related NAD-dependent methanol dehydrogenase was involved in the initial oxidation of methanol. In cells of Bacillus sp. C1 grown under methanol-limiting conditions this enzyme constituted a high percentage of total soluble protein. The methanol dehydrogenase from this organism was purified to homogeneity and characterized. In cell-free extracts the enzyme displayed biphasic kinetics towards methanol, with apparent Km values of 3.8 and 166 mM. Carbon assimilation was by way of the fructose-1,6-bisphosphate aldolase cleavage and transketolase/transaldolase rearrangement variant of the RuMP cycle of formaldehyde fixation. The key enzymes of the RuMP cycle, hexulose-6-phosphate synthase (HPS) and hexulose-6-phosphate isomerase (HPI), were present at very high levels of activity. Failure of whole cells to oxidize formate, and the absence of formaldehyde- and formate dehydrogenases indicated the operation of a non-linear oxidation sequence for formaldehyde via HPS. A comparison of the levels of methanol dehydrogenase and HPS in cells of Bacillus sp. C1 grown on methanol and glucose suggested that the synthesis of these enzymes is not under coordinate control.

Alcohol Oxidoreductases↗
PubMed1998

Curvilinear increase in methanol concentration after inhibition of oxidation by ethanol: significance for the investigation of endogenous methanol concentration and formation.

Endogenous methanol production was assessed over a period of 5 h in subjects given an infusion of ethanol to inhibit methanol oxidation in the liver after a period of fasting and abstinence from alcohol. Ethanol was administered to each of five subjects at rates of 0.35 g/kg per hour and 0.70 g/kg per hour. The rise in methanol concentration was biphasic regardless of the rate of ethanol administration, with a steeper gradient in the first 10-30 min. This may be due to the existence of a deep compartment from which methanol can be displaced by ethanol. This could take the form of loose binding of methanol to the hepatic oxidation enzymes as an enzyme-substrate complex, or a shift of the oxidation-reduction equilibrium between methanol and formaldehyde. The biphasic nature of the increase, with an initial steeper rise, means that the values obtained in the first 30 min should be excluded from the calculations when the rate of endogenous methanol production is determined by linear regression analysis. Endogenous methanol concentrations to be taken into account after ethanol administration are on average 0.4-0.6 mg/kg higher than those detectable in the absence of ethanol due to the additional method displaced from the deep compartment.

Adult↗
PubMed2006

Inhalational abuse of methanol products: elevated methanol and formate levels without vision loss.

Inhalant abuse of methanol-containing products has increased over the last decade. We performed a prospective observational study of 7 subjects who presented to an ED after inhalant abuse of methanol-containing hydrocarbon products. Four patients had a methanol level greater than 24 mg/dL and 2 had an anion gap greater than 17 mEq/L. The mean formic acid level was 71 microg/mL, and 1 patient had a level considered high enough to induce retinal toxicity (>200 microg/mL). No patient had an abnormal ophthalmologic examination. All patients were treated with intravenous folate, 2 received alcohol dehydrogenase blockade, and no patient received hemodialysis or intravenous bicarbonate. All patients' acidosis resolved within 4 hours. The methanol and formic acid levels are lower than those reported after methanol ingestion. These preliminary data suggest that inhalant abusers of methanol products may have significantly elevated methanol and formic acid levels, but are at low risk for methanol induced complications of visual dysfunction and refractory acidosis.

Acidosis↗
PubMed2006

Molecular dynamics simulations of liquid methanol and methanol-water mixtures with polarizable models.

A polarizable model for simulation of liquid methanol, compatible with the COS/G2 water model, has been developed using the Charge-on-Spring (COS) technique. The model consists of three point charges, with one polarizable center on the oxygen atom. The Lennard-Jones parameters on the oxygen atom together with the molecular polarizability were varied to reproduce the experimental heat of vaporization and density of liquid methanol at ambient conditions. We examined the energies of various methanol dimers in the gas phase and compared them with values obtained from ab initio calculations. The model was then used to study the thermodynamic, dynamic, structural, and dielectric properties of liquid methanol as well as of a methanol-water mixture. A microscopic picture of the structure of pure liquid methanol and of the methanol-water mixture is provided. Good agreement was found between the results from our model simulations and available experimental and ab initio calculation data. In particular, the experimental dielectric permittivity of 32 could be reproduced, which had been shown to be difficult when using nonpolarizable models.

Dimerization↗
PubMed1987

Isolation, complementation and partial characterization of mutants of the methanol autotroph Xanthobacter H4-14 defective in methanol dissimilation.

Seven mutants of Xanthobacter H4-14, unable to grow on methanol but capable of growth on formate, were isolated and complemented with a chromosomal clone bank constructed in the broad-host-range cosmid pVK100. One mutant could not be complemented but the others fell into four distinct complementation groups that involved three different recombinant clones. All of the complementing regions were separated by at least 10 kbp. The five complementation classes had different phenotypic characteristics and were defective in different aspects of methanol and formaldehyde oxidation. Class I mutants were defective in methanol oxidation, class II mutants were impaired in formaldehyde oxidation, class III mutants appeared to be defective in a regulatory element involving the methanol oxidation system, and class IV mutants appeared to be defective in a regulatory element involving formaldehyde oxidation. Class V mutants exhibited a methanol-sensitive phenotype, which was correlated with an imbalance between methanol and formaldehyde dehydrogenase activities. Analysis of this class suggested it was defective in a repressor that regulated methanol dissimilation functions.

Alcohol Oxidoreductases↗
PubMed1978

Microbial oxidation of methane and methanol: crystallization of methanol dehydrogenase and properties of holo- and apomethanol dehydrogenase from Methylomonas methanica.

Procedures are described for the purification and crystallization of methanol dehydrogenase from the soluble fraction of the type I obligate methylotroph Methylomonas methanica strain S1. The crystallized enzyme is homogeneous as judged by acrylamide gel electrophoresis and ultracentrifugation. The enzyme had a high pH optimum (9.5) and required ammonium salt as an activator. In the presence of phenazine methosulfate as an electron acceptor, the enzyme catalyzed the oxidation of primary alcohols and formaldehyde. Secondary, tertiary, and aromatic alcohols were not oxidized. The molecular weight as well as subunit size of methanol dehydrogenase was 60,000, indicating that it is monomeric. The sedimentation constant (s(20,w)) was 3.1S. The amino acid composition of the crystallized enzyme is also presented. Antisera prepared against the crystalline enzyme were nonspecific; they cross-reacted with and inhibited the isofunctional enzyme from other obligate methylotrophic bacteria. The crystalline methanol dehydrogenase had an absorption peak at 350 nm in the visible region and weak fluorescence peaks at 440 and 470 nm due to the presence of a pteridine derivative as the prosthetic group. A procedure was developed for the preparation of apo-methanol dehydrogenase. The molecular weights, sedimentation constants, electrophoretic mobilities, and immunological properties of apo- and holo-methanol dehydrogenases are identical. Apo-methanol dehydrogenase lacked the absorption peak at 350 nm and the fluorescence peaks at 440 and 470 nm and was catalytically inactive. All attempts to reconstitute an active enzyme from apo-methanol dehydrogenase, using various pteridine derivatives, were unsuccessful.

Alcohol Oxidoreductases↗
PubMed1996

Perinatal methanol exposure in the rat. I. Blood methanol concentration and neural cell adhesion molecules.

Although the acute toxicity of methanol is well documented, few studies have addressed the consequences of perinatal exposures to the low concentrations that are expected to arise from its proposed use as a component of automobile fuel. This report describes the general research design of a series of studies, the effects of methanol exposures on blood concentrations in dams and neonates, and indices of brain development. Four cohorts of Long-Evans pregnant rats, each cohort consisting of an exposure (n = 12) and a control (n = 12) group, were exposed whole-body to 4500 ppm methanol vapor or air for 6 hr daily beginning on Gestation Day 6. Both dams and pups were then exposed through Postnatal Day 21 (PND 21). Blood methanol concentrations determined by gas chromatography from samples obtained immediately following a 6-hr exposure reached approximately 500-800 micrograms/ml in the dams during gestation and lactation. Average concentrations for pups attained levels about twice those of the dams. Selected offspring from Cohort 4 were exposed for one additional 6-hr session at ages that extended out to PND 52. Regression analyses showed that the blood methanol concentrations of the pups declined until about PND 48, at which time their levels approximated those of their dams. Such pharmacokinetic differences might increase the risks posed to developing organisms. Light-microscopic analysis showed no significant abnormalities in the brains of the methanol-treated animals. However, assays of neural cell adhesion molecules (NCAMs) in brains of pups sacrificed on PND 4 showed staining for both the 140 and the 180 kDa isoforms to be less intense in the cerebellum of exposed animals. NCAM differences were not apparent in animals sacrificed 15 months after their final exposure.

Animals↗
PubMed1976

Cytochemical studies on the localization of methanol oxidase and other oxidases in peroxisomes of methanol-grown Hansenula polymorpha.

The localization of methanol oxidase activity in cells of methanol-limited chemostat cultures of the yeast Hansenula polymorpha has been studied with different cytochemical staining techniques. The methods were based on enzymatic or chemical trapping of the hydrogen peroxide produced by the enzyme during aerobic incubations of whole cells in methanol-containing media. The results showed that methanol-dependent hydrogen peroxide production in either fixed or unfixed cells exclusively occurred in peroxisomes, which characteristically develop during growth of this yeast on methanol. Apart from methanol oxidase and catalase, the typical peroxisomal enzymes D-aminoacid oxidase and L-alpha-hydroxyacid oxidase were also found to be located in the peroxisomes. Urate oxidase was not detected in these organelles. Phase-contrast microscopy of living cells revealed the occurrence of peroxisomes which were cubic of form. This unusual shape was also observed in thin sections examined by electron microscopy. The contents of the peroxisomes showed, after various fixation procedures, a completely crystalline or striated substructure. It is suggested that this substructure might represent the in vivo organization structure of the peroxisomal enzymes.

Alcohol Oxidoreductases↗