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At least 55 records · Page 3Linked to original sources
PubMed1976

Oxidation of methanol, formaldehyde and formic acid by methanol-utilizing yeast.

Methanol-utilizing yeast, Candida boidini 11 Bh, characterized by high tolerance to methanol during growth, displays even higher tolerance when the oxidation rate by intact cells is tested. Low respiration activity is found even at 22% v/v of methanol. The half-saturation constant was 17-18 mM. The half-saturation constants for the two oxidation intermediates, formaldehyde and formic acid were 3.5-4.0 an .d 30-33 mM, respectively. When applied together with standard concentration of methanol, very low concentrations of both intermediates stimulated the oxidation rate. These results are discussed in connection with the relationship between growth and oxidation, the tolerance to high concentrations of inhibitory products and the mechanism of inhibition.

Candida↗
PubMed2000

Characterization of methanol-soluble and methanol-insoluble proteins from developing peanut seed.

The 85% methanol-soluble proteins are known to specifically contribute to the production of flavor of roasted peanut. To determine the nature of the 85% methanol-soluble proteins, they were isolated from the peanut seed, and the 85% methanol-soluble (MS) and 85% methanol-insoluble (MIS) fractions were characterized using polyacrylamide gel electrophoresis (PAGE) and capillary electrophoresis. The results showed that the 85% MS fraction contained lower amounts (9-10%) of protein than the MIS fraction (15-33%). Protein content of the MIS fraction increased more significantly during seed maturation than it did in the MS fraction. Unlike the protein, free amino acids and soluble sugars levels of the MS fraction decreased significantly during seed maturation. The 85% MS fraction contained predominantly low molecular weight (<20 kDa) proteins/polypeptides, whereas the MIS fraction contained a mixture of polypeptides with molecular weight between 14 kDa and 90 kDa. SDS-PAGE showed no major changes in the polypeptide composition of the MS fraction during seed maturation. Capillary electrophoretic analysis revealed major qualitative and quantitative changes in the protein and polypeptide composition of the MS and MIS fractions during seed maturation. Fatty acid analysis of these fractions indicated that the MS fraction is lipoprotein in nature and rich in oleic and linoleic acids.

Amino Acids↗
PubMed1999

Isolation and characterization of a mutant defective in the production of methanol dehydrogenase from a new restricted facultative methanol-oxidizing bacterium.

A new restricted facultative methanol-oxidizing bacterium Methylobacillus sp. strain SK1 (DSM 8269) was subjected to insertion mutagenesis studies with the transposon Tn5 to generate mutants deficient in the production of methanol dehydrogenase (MDH). The transposon was conjugally transferred into the methylotroph by using the triparental mating procedure. The mutants induced by Tn5 were selected directly from a plate containing succinate by using the allyl alcohol selection procedure. The transposition of Tn5 to the bacterium showed a moderate transposition frequency (10(-5) - 10(-6)). Southern hybridization analysis confirmed that the transposon Tn5 was inserted into the chromosomal DNA of the mutants. In addition, the mutants had no RNA transcripts produced from the mdh gene, as judged by Northern blot analysis. The mutants could neither grow on methanol nor produce MDH protein, as determined by Western blot analysis with anti-MDH antibody. These results suggest that Tn5 mutagenesis maybe a useful tool for the molecular analysis of a facultative methanol-oxidizing bacterium.

Alcohol Oxidoreductases↗
PubMed1997

Methanol:coenzyme M methyltransferase from Methanosarcina barkeri. Zinc dependence and thermodynamics of the methanol:cob(I)alamin methyltransferase reaction.

In Methanosarcina barkeri, methanogenesis from methanol is initiated by the formation of methyl-coenzyme M from methanol and coenzyme M. This methyl transfer reaction is catalyzed by two enzymes, designated methyltransferases 1 (MT1) and 2 (MT2). Transferase MT1, which is composed of a 50-kDa subunit, MtaB, and a 27-kDa corrinoid-harbouring subunit, MtaC, has been shown recently to catalyze the methylation of free cob(I)alamin with methanol [Sauer, K., Harms, U. & Thauer, R. K. (1997) Eur. J. Biochem. 243, 670-677]. We report here that this reaction is catalyzed by subunit MtaB overproduced in Escherichia coli. MtaB also catalyzed the formation of methanol from methylcobalamin and H2O, the hydrolysis being associated with a free-energy change deltaG(o)' of approximately +7.0 kJ/mol. MtaB was found to contain 1 mol zinc, and its activity to be zinc dependent (pK(Zn2+) = 9.3). The zinc dependence of the MT2 (MtaA)-catalyzed reaction is also described (pK(Zn2+) = 9.6).

Archaeal Proteins↗
PubMed1998

Sequence and characterization of mxaB, a response regulator involved in regulation of methanol oxidation, and of mxaW, a methanol-regulated gene in Methylobacterium extorquens AM1.

In the facultative serine cycle methylotroph Methylobacterium extorquens AM1, mxaB is required for regulation of methanol oxidation and is located at the end of a large cluster of methylotrophy genes that begins with mxaF. The sequence of mxaB has been obtained and indicates that the gene product is a member of the response regulator family. None of the open reading frames near mxaB showed sequence identity to sensor kinases. Complementation studies suggest a promoter may be located adjacent to mxaB. Another gene (mxaW) is present immediately upstream of mxaF, divergently transcribed from a methanol-inducible promoter. The sequence in the region of mxaW was also obtained. MxaW showed no identity to known proteins. Mutations in mxaW and in an adjacent open reading frame, OrfR, had no effect on growth of M. extorquens AM1 on methanol or other substrates. The MxaW mutant had normal methanol dehydrogenase activity and normal transcription of the mxaF promoter. Therefore, the function of mxaW is unknown.

Alcohol Oxidoreductases↗
PubMed2005

Methanol-dependent gene expression demonstrates that methyl-coenzyme M reductase is essential in Methanosarcina acetivorans C2A and allows isolation of mutants with defects in regulation of the methanol utilization pathway.

Methanosarcina acetivorans C2A is able to convert several substrates to methane via at least four distinct methanogenic pathways. A common step in each of these pathways is the reduction of methyl-coenzyme M (CoM) to methane catalyzed by methyl-CoM reductase (MCR). Because this enzyme is used in each of the known pathways, the mcrBDCGA operon, which encodes MCR, is expected to be essential. To validate this prediction, a system for conditional gene inactivation was developed. A heterologous copy of the mcrBDCGA operon was placed under the control of the highly regulated mtaC1 promoter, which directs the expression of genes involved in methanol utilization, and recombined onto the M. acetivorans chromosome. This allowed for disruption of the endogenous mcr operon in the presence of methanol. Because the PmtaC1 promoter is transcribed only during growth on methanol, mcrBDCGA was rendered methanol dependent and the strain was unable to grow in trimethylamine media, strongly suggesting that mcrBDCGA is essential. Upon prolonged incubation, suppressed mutants which expressed mcrBDCGA constitutively could be selected. Expression analysis of PmtaC1::uidA gene fusions in several isolated suppressed mutants suggests that they carry trans-active mutations leading to deregulation of all genes under control of this promoter. Subsequently, proteome analysis of one such suppressed mutant revealed that all known proteins derived from mtaC1 promoter-dependent expression were constitutively expressed in this mutant. This genetic system can therefore be employed for the testing of essential genes and for the identification of genes under a common regulatory mechanism by making regulatory mutations phenotypically selectable.

Gene Deletion↗
PubMed2002

Solubility of hypericin in methanol and methanol-pyridine.

The solubility of hypericin in methanol and methanol-pyridine (99:1, v/v) was determined. The addition of pyridine turned out to enhance the solubility of hypericin. In pure methanol only 37.17 micrograms/ml could be dissolved. In comparison, 320.91 micrograms hypericin were soluble in one ml methanol-pyridine (99:1, v/v).

Anthracenes↗
PubMed1995

[Methanol from ethanol? On cleavage of the ethanol carbon bond and methanol formation within the scope of microbial metabolic processes].

While making investigations into microbiological literature, the following question was looked into: Are microorganisms able to generate methanol from the basic carbon frame of ethanol? Due to carbon monoxide dehydrogenase complexes some methanogens and acetate oxidisers are able to cleave the carbon bond of acetyl-CoA. Coenzyme bonded methyl groups (methyl-H4MPT, methyl-CoM, methyl-THF) are generated both by means of reduction (methano-genesis) and by means of oxidation (CO2 evolution) of the C2-unit. Usually these are looked at as precursors of methanol. Methanotrophs and certain methylotrophs are able to oxidise methane to methanol by means of oxigenase complexes. The C1-unit supplies coenzyme bonded CO; carbon monoxide can be reduced to methanol very effectively by several Clostridia. Both in vivo analysis of intestinal gases of alcoholised individuals and incubation experiments with certain intestinal groups with marked alcohol, might contribute in judging the real importance of the intestinal micro flora with regard to the problems of ethanol congeners.

Alcoholic Intoxication↗
PubMed1994

[Methanol formation in vitro and in vivo (methanol formation after pectin administration)].

1. In the course of 34 days the detectable methanol concentration in freshly squeezed grapefruit and organ juices as well as in grapefruit and orange juice mixes increased to a maximum level of approximately 600 mg/kg. This increase could already be detected at the beginning of the examination i.e. as early as 1 or 2 days after squeezing the fruit juices. At the beginning of the experiments the methanol concentrations were between 10 and 270 mg/kg. 2. After the consumption of pectin (40 g on one day and 2 x 40 g on two days) blood or serum-methanol values respectively were observed which were clearly above the level of chronic alcohol abuse (10 mg/kg). After the ingestion of ethanol (0.5 g/kg bodyweight) the serum-methanol concentration increased even further.

Adult↗
PubMed1975

Oxidation of methanol, formaldehyde and formate by catalase purified from methanol-grown Hansenula polymorpha.

Catalase has been partially purified from cell-free extracts of methanol-grown Hansenula polymorpha and its peroxidative properties were studied. It was shown that the enzyme is capable of oxidizing methanol, formaldehyde and formate in the presence of hydrogen peroxide. The physiological significance of these reactions in the transduction of energy from the oxidation of methanol in yeasts is discussed.

Ascomycota↗
PubMed2005

Proton transfer of excited 7-azaindole in reverse-micellar methanol nanopools: even faster than in bulk methanol.

The methanol-catalyzed double-proton transfer of photoexcited 7-azaindole in the free cores of solvation-restricted reverse micelles takes place on the time scale of 90 ps, even shorter than in bulk methanol. This anomalous rate increase with a large kinetic isotope effect of 5 experimentally proves the widely discussed two-step model for the overall reaction of solvent-mediated proton transfer. On the other hand, the molecules in the bound layers and in the headgroup layers relax in 900 and 6000 ps, respectively, without going through proton transfer. The tautomerization and the relaxation of excited 7-azaindole can be exploited to probe the nanopools of methanol reverse micelles.

Indoles↗
PubMed2002

Genomic and proteomic analyses reveal multiple homologs of genes encoding enzymes of the methanol:coenzyme M methyltransferase system that are differentially expressed in methanol- and acetate-grown Methanosarcina thermophila.

Each of the genomic sequences of Methanosarcina acetivorans, Methanosarcina mazei, and Methanosarcina thermophila revealed two homologs of mtaA, three homologs of mtaB, and three homologs of mtaC encoding enzymes specific for methanogenesis from methanol. Two-dimensional gel electrophoretic analyses of polypeptides from M. thermophila established that methanol induces the expression of mtaA-1, mtaB-1, mtaB-2, mtaB-3, mtaC-1, mtaC-2, and mtaC-3 whereas mtaB-3 and mtaC-3 are constitutively expressed in acetate-grown cells. The gene product of one of three mttC homologs, encoding trimethylamine-specific methyltransferase I, was detected in methanol- but not acetate-grown M. thermophila. A postulated role for the multiple homologs is discussed.

Acetates↗
PubMed2007

The preferred reaction path for the oxidation of methanol by PQQ-containing methanol dehydrogenase: addition-elimination versus hydride-transfer mechanism.

The catalytic oxidation of methanol to formaldehyde by pyrroloquinoline quinone (PQQ)-containing methanol dehydrogenase (MDH) was investigated at density functional B3LYP level. The still controversial addition-elimination and hydride-transfer reaction mechanisms were analysed. Computations performed in the gas phase and in the protein environment indicated that both suggested reaction sequences involve very high activation barriers. In this situation, the reactions should have scarce probability to occur and the preference for one of the two paths cannot be stated. Here, we will show how some corrections to the successive steps in the addition-elimination mechanism can sensibly decrease the activation barriers height, making possible the determination of the MDH-preferred catalytic path.

Alcohol Oxidoreductases↗
PubMed1994

Pharmacokinetics of inhaled [14C]methanol and methanol-derived [14C]formate in normal and folate-deficient cynomolgus monkeys.

Large-scale use of methanol (MeOH) as an automotive fuel may increase exposure of the public to MeOH vapor, necessitating the need for additional data for an adequate human health risk assessment. Formate is accepted as the toxic metabolite of MeOH, its metabolism is folate-dependent, and potentially sensitive folate-deficient subpopulations (e.g., pregnant women) exist that may be at higher risk to low-level methanol exposure. This study determined the pharmacokinetics of [14C]MeOH and [14C]formate in normal and folate-deficient (FD) monkeys following inhalation of environmentally relevant concentrations of [14C]MeOH. Four normal adult female cynomolgus monkeys were anesthetized (isoflurane) and exposed by lung-only inhalation to 10, 45, 200, and 900 ppm [14C]MeOH for 2 hr. Monkeys were then placed on a FD diet until folate concentrations consistent with moderate deficiency (29-107 ng/ml) developed in red blood cells and then reexposed to 900 ppm (900-FD) for 2 hr. Average (+/- SD) end-of-exposure blood [14C]MeOH concentrations were 0.65 +/- 0.3, 3.0 +/- 0.8, 21 +/- 16, 106 +/- 84, and 211 +/- 71 microM, while average (+/- SD) peak blood [14C]formate concentrations were 0.07 +/- 0.02, 0.25 +/- 0.09, 2.3 +/- 2.9, 2.8 +/- 1.7, and 9.5 +/- 4.7 microM following MeOH inhalation at 10, 45, 200, 900, and 900-FD ppm, respectively. The blood concentration of [14C]MeOH-derived formate from all exposures was 10 to 1000 times lower than the endogenous blood formate concentration (0.1 to 0.2 mM) reported for monkeys. These results suggest that low-level exposure to MeOH would not result in elevated blood formate concentrations in humans under short-term exposure conditions.

Administration, Inhalation↗
PubMed1973

Treatment of falciparum malaria from Vietnam with a phenanthrene methanol (WR 33063) and a quinoline methanol (WR 30090).

Two new investigational antimalarial drugs developed by the U.S. Army Malaria Research Program were tested in patients with multi-drug-resistant falciparum malaria from Vietnam. WR 33063, a phenanthrene methanol, cured 13 patients treated in the United States. All of these patients had suffered multiple recrudescences after treatment with standard antimalarial drugs. In addition, 23 of 25 patients with acute attacks of falciparum malaria treated in Vietnam were cured. The rate of clinical response was prompt. WR 30090, a quinoline methanol, similarly cured eight patients with multiple recrudescences in the United States and 23 of 26 patients in Vietnam. Adverse effects associated with the drugs were not seen. These drugs signify a major advance in the chemotherapy of drug-resistant falciparum malaria.

Antimalarials↗
PubMed1975

Pyridine nucleotide-linked oxidation of methanol in methanol-assimilating yeasts.

An alcohol dehydrogenase linked to nicotinamide adenine dinucleotide and requiring glutathione has been isolated and partially purified from two methanol-assimilating yeasts. It differs from previously described methanol-oxidizing enzymes in pH optima, electron acceptor specificity, substrate specificity, inhibition pattern, and stability.

Alcohol Oxidoreductases↗
PubMed1975

Comparison of a 9-phenanthrene methanol (WR33063), a 4-quinoline methanol (WR30090), and quinine for falciparum malaria in Thailand.

Quinine was compared with a 9-phenanthrene methanol (WR33063) and a 4-quinoline methanol (WR30090) for the treatment of 207 patients with falciparum malaria in Southeast Thailand. Quinine eradicated parasitaemia (average 70 hours) more rapidly than either WR30090 (72 hours) or WR33063 (77 hours). But WR33063 had a higher cure rate (92%) than WR30090 (86%) or quinine (85%). The mean duration of fever and of parasitaemia were combined with the failure rate to form an arbitrary efficacy index. Using this concept WR33063 was the most effective drug. The recrudescence rate correlated with the degree and duration of parasitaemia and with the duration of fever. WR33063 was the least toxic drug. Side effects associated with WR30090 appeared to be headache, backache and urticaria. Quinine was the most toxic drug. All 3 drugs were inconvenient in having to be administered every 8 hours for 6 days. One patient did not respond to oral quinine but did respond to an intravenous quinine infusion (IVQ). A "Medication Ward Round" was perfected during the study and comprised sequential history, drug administration, physical examination, dose notation and patient observation. Falciparum nephrosis was diagnosed in one patient.

Adolescent↗
PubMed2005

High-pressure and -temperature viscosity measurements of methanol and 4:1 methanol:ethanol solution.

Viscosity (eta) measurements using rolling sphere viscometry in a resistance-heated diamond-anvil pressure cell yield activation energies of 18-98 kJmol over a pressure range of 1.1-6.1 GPa for methanol and 26-78 kJmol over a pressure range of 2.9-5.4 GPa for a 4:1 methanol:ethanol solution. Nonlinear models of log eta (free-volume and power-law models) yield statistically better fits than the Arrhenius model at room temperature and extrapolate to lower glass-transition (10(12) Pa s) pressures. Glass-transition pressures for the free-volume model change little over the temperature range studied (298-338 K), whereas the power-law values converge to those of the Arrhenius model at temperatures above 320 K.

Journal Article↗