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A Felix

Publications and source records attributed to A Felix.

13 recordsLinked to original sources
PubMed1979

Microbial oxidation of methane and methanol: purification and properties of a heme-containing aldehyde dehydrogenase from Methylomonas methylovora.

Procedures for the purification of an aldehyde dehydrogenase from extracts of the obligate methylotroph, Methylomonas methylovora are described. The purified enzyme is homogeneous as judged from polyacrylamide gel electrophoresis. In the presence of an artificial electron acceptor (phenazine methosulfate), the purified enzyme catalyzes the oxidation of straight chain aldehydes (C1--C10 tested), aromatic aldehydes (benzaldehyde, salicylaldehyde), glyoxylate, and glyceraldehyde. Biological electron acceptors such as NAD+, NADP+, FAD, FMN, pyridoxal phosphate, and cytochrome c cannot act as electron carriers. The activity of the enzyme is inhibited by sulfhydryl agents [p-chloromercuribenzoate, N-ethylmaleimide and 5,5-dithiobis (2-nitrobenzoic acid)], cuprous chloride, and ferrour nitrate. The molecular weight of the enzyme as estimated by gel filtration is approximately 45000 and the subunit size determined by sodium dodecyl sulfate-gel electrophoresis is approximately 23000. The purified enzyme is light brown and has an absorption peak at 410 nm. Reduction of enzyme with sodium dithionite or aldehyde substrate resulted in the appearance of peaks at 523 nm and 552nm. These results suggest that the enzyme is a hemoprotein. There was no evidence that flavins were present as prosthetic group. The amino acid composition of the enzyme is also presented.

Aldehyde Oxidoreductases↗
PubMed1979

Microbial production of methyl ketones. Purification and properties of a secondary alcohol dehydrogenase from yeast.

Cell-free extracts derived from yeasts Candida utilis ATCC 26387, Hansenula polymorpha ATCC 26012, Pichia sp. NRRL-Y-11328 Torulopsis sp. strain A1 and Kloeckera sp. strain A2 catalyzed an NAD+-dependent oxidation of secondary alcohols (2-propanol, 2-butanol, 2-pentanol, 2-hexanol) to the corresponding methyl ketones (acetone, 2-butanone, 2-pentanone, 2-hexanone). We have purified a NAD+-specific secondary alcohol dehydrogenase from methanol-grown yeast, Pichia sp. The purified enzyme is homogenous as judged by polyacrylamide gel electrophoresis. The purified enzyme catalyzed the oxidation of secondary alcohols to the corresponding methyl ketones in the presence of NAD+ as an electron acceptor. Primary alcohols were not oxidized by the purified enzyme. The optimum pH for oxidation of secondary alcohols by the purified enzyme is 8.0. The molecular weight of the purified enzyme as determined by gel filtration is 98 000 and subunit size as determined by sodium dodecyl sulfate gel electrophoresis is 48 000. The activity of the purified secondary alcohol dehydrogenase was inhibited by sulfhydryl inhibitors and metal-binding agents.

Alcohol Oxidoreductases↗
PubMed1979

Oxidation of secondary alcohols to methyl ketones by yeasts.

Cell suspensions of yeasts, Candida utilis ATCC 26387, Hansenula polymorpha ATCC 26012, Pichia sp. NRRL-Y-11328, Torulopsis sp. strain A1, and Kloeckera sp. strain A2, grown on various C-1 compounds (methanol, methylamine, methylformate), ethanol, and propylamine catalyzed the oxidation of secondary alcohols to the corresponding methyl ketones. Thus, isopropanol, 2-butanol, 2-pentanol, and 2-hexanol were converted to acetone, 2-butanone, 2-pentanone, and 2-hexanone, respectively. Cell-free extracts derived from methanol-grown yeasts catalyzed an oxidized nicotinamide adenine dinucleotide-dependent oxidation of secondary alcohols to the corresponding methyl ketones, Primary alcohols were not oxidized. The effect of various environmental factors on the production of methyl ketones from secondary alcohols by methanol-grown Pichia sp. was investigated.

Alcohol Oxidoreductases↗
PubMed1979

Microbial oxidation of gaseous hydrocarbons. II. Hydroxylation of alkanes and epoxidation of alkenes by cell-free particulate fractions of methane-utilizing bacteria.

Cell-free particulate fractions derived from methylotrophic bacteria catalyze the oxygen- and reduced nicotinamide adenine dinucleotide-dependent epoxidation of alkenes and hydroxylation of alkanes. Evidence presented indicates that the hydroxylation and epoxidation reactions are catalyzed by the same or a similar metal-containing monooxygenase.

Alkanes↗
PubMed1979

Measurement of myocardial PCO2 with a microelectrode: its relation to coronary sinus PCO2.

A micro-PCO2 electrode, with dimensions of 1 x 10 mm, and a 63% response time of 14 s was inserted into the left ventricular myocardium of the pentobarbital-anesthetized dog. Continuous recordings were made of myocardial PCO2 (PmCO2), arterial PCO2 (PaCO2), and coronary sinus PCO2 (CSPCO2) during variation of respiratory rate. PmCO2 and CSPCO2 were compared at varying coronary flow. PmCO2 was similar to and closely followed changes in CSPCO2. The difference between PmCO2 and CSPCO2 was -0.52 +/- 3.63 (SD) mmHg, and PmCO2 exceeded PaCO2 by 20.69 +/- 5.12 mmHg. After coronary occlusion, PmCO2, rose promptly, but CSPCO2 was only slightly elevated until the occlusion was released, when a CO2 efflux into the coronary sinus occurred. It is concluded that the electrode measures extracellular PCO2 and that extracellular and myocardial PCO2 are essentially equal. PmCO2 rises rapidly following coronary occlusion.

Animals↗
PubMed1979

Rate of rise of myocardial PCO2 during early myocardial ischemia in the dog.

We have investigated the rate of rise of myocardial PCO2 (PmCO2) after coronary artery occlusion using a new method for this measurement. Previous studies of PmCO2 have been limited by the slow response of the only available method, and no increase in MmCO2 prior to 3 minutes after occlusion has been found. We have implanted a miniature PCO2 electrode, with a 63% response time of 14 seconds, into the left ventricle of 14 open-chest dogs. After abrupt coronary occlusion, PmCO2 began to rise in 13.6 +/- 1.1 seconds in heparinized dogs and in 7.5 +/- 0.7 seconds in unheparinized dogs. The subsequent magnitude of the increase in PmCO2 was 24, 88, 171, and 222 mm Hg at 2, 5, 10, and 15 minutes after occlusion. The rate of rise of PmCO2 was essentially linear from 1 minute to 10 minutes at a rate of 18.3 mm Hg/min. The rate of rise was slower during the first 30 seconds after occlusion (6.1 mm Hg/min) and also from 30 seconds to 1 minute (9.7 mm Hg/min). This rate of rise is much greater than that previously observed and reflects the severe myocardial acidosis developing during ischemia. A rise in PmCO2 is one of the earliest metabolic changes that has been observed during myocardial ischemia.

Animals↗
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↗
PubMed1978

Microbial oxidation of methane and methanol: isolation of methane-utilizing bacteria and characterization of a facultative methane-utilizing isolate.

A methane-utilizing organism capable of growth both on methane and on more complex organic substrates as a sole source of carbon and energy, has been isolated and studied in detail. Suspensions of methane-grown cells of this organism oxidized C-1 compounds (methane, methanol, formaldehyde, formate); hydrocarbons (ethane, propane); primary alcohols (ethanol, propanol); primary aldehydes (acetaldehyde, propionaldehyde); alkenes (ethylene, propylene); dimethylether; and organic acids (acetate, malate, succinate, isocitrate). Suspensions of methanol-or succinate-grown cells did not oxidize methane, ethane, propane, ethylene, propylene, or dimethylether, suggesting that the enzymatic systems required for oxidation of these substrates are induced only during growth on methane. Extracts of methane-grown cells contained a particulate reduced nicotinamide adenine dinucleotide-dependent methane monooxygenase activity. Oxidation of methanol, formaldehyde, and primary alcohols was catalyzed by a phenazine methosulfate-linked, ammonium ion-requiring methanol dehydrogenase. Oxidation of primary aldehydes was catalyzed by a phenazine methosulfate-linked, ammonium ion-independent aldehyde dehydrogenase. Formate was oxidized by a nicotinamide adenine dinucleotide-specific formate dehydrogenase. Extracts of methane-grown, but not succinate-grown, cells contained the key enzymes of the serine pathway, hydroxypyruvate reductase and malate lyase, indicating that the enzymes of C-1 assimilation are induced only during growth on C-1 compounds. Glucose-6-phosphate dehydrogenase was induced during growth on glucose. Extracts of methane-grown cells contained low levels of enzymes of the tricarboxylic acid cycle, including alpha-keto glutarate dehydrogenase, relative to the levels found during growth on succinate.

Alcohol Oxidoreductases↗
PubMed1978

Relative effect of CO2 on canine coronary vascular resistance.

We determined the effect of alterations in coronary arterial PCO2 on coronary vascular resistance (CVR) at a constant coronary sinus (CS) PO2 and the effect of coronary arterial PO2 variation on CVR at a constant CS PCO2. A linear but opposing effect on CVR was found for both gases. The sensitivity of CVR to O2 change, represented as CVR/CS PO2, was approximately twice that of the ratio CVR/CS PCO2. (0.0852 +/- 0.006 vs. -0.0362 +/- 0.005). The entire range of CVR variation obtainable through CO2 variation was as great as that resulting from O2 variation. During randomized variation of O2 and CO2, CVR can be mathematically related in a multiple linear expression to CS PO2 and CS PCO2.

Animals↗
PubMed1976

Catechol 1,2-dioxygenase from Acinetobacter calcoaceticus: purification and properties.

Procedures for the purification of catechol 1,2-dioxygenase from extracts of Acinetobacter calcoaceticus strain ADP-96 are described. The purified enzyme was homogeneous as judged by ultracentrifugation and acrylamide gel electrophoresis. The enzyme contained 2 g-atoms of iron per mol of protein. The enzyme had a broad substrate specificity and catalyzed the oxidation of catechol, 4-methylcatechol, 3-methylcatechol, and 3-isopropyl catechol. The activity of the enzyme was inhibited by heavy metals, sulfhydryl inhibitors, and substrate analogues. The molecular weight of the enzyme was 85,000 as estimated by filtration on Bio-Gel agarose and 81,000 as estimated by sedimentation equilibrium analysis. The subunit size determined by sodium dodecyl sulfate-gel electrophoresis was 40,000. The amino terminal amino acid was methionine. The amino acid composition and spectral properties of 1,2-dioxygenase are also presented. Antisera prepared against the purified enzyme cross-reacted and inhibited enzyme activity in crude extracts from the other strain of A. calcoaceticus, but failed to cross-react and inhibit isofunctional enzyme from organisms of the genera Pseudomonas, Alcaligenes, and Nocardia.

Acinetobacter↗
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↗