Rotational study of the bimolecule acetic acid-fluoroacetic acid

The rate of the aerobic metabolism of pyruvic acid by bakers' yeast cells is determined mainly by the amount of undissociated acid present. As a consequence, the greatest rate of oxidation was observed at pH 2.8. Oxidation, at a slow rate, started at pH 1.08; at pH 9.4 there was no oxidation at all. The anaerobic metabolism, only a fraction of the aerobic, was observed only in acid solutions. There was none at pH values higher than 3. Pyruvic acid in the presence of oxygen was oxidized directly to acetic acid; in the absence of oxygen it was metabolized mainly by dismutation to lactic and acetic acids, and CO2. Acetic acid formation was demonstrated on oxidation of pyruvic acid at pH 1.91, and on addition of fluoroacetic acid. Succinic acid formation was shown by addition of malonic acid. These metabolic pathways in a cell so rich in carboxylase may be explained by the arrangement of enzymes within the cell, so that carboxylase is at the center, while pyruvic acid oxidase is located at the periphery. Succinic and citric acids were oxidized only in acid solutions up to pH 4. Malic and α-ketoglutaric acids were not oxidized, undoubtedly because of lack of penetration.

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THE FORMATION OF ACETATE IN BRAIN TISSUE SUSPENSIONS

Canadian Journal of Research ◽

10.1139/cjr48e-012 ◽

1948 ◽

Vol 26e (4) ◽

pp. 239-249 ◽

Cited By ~ 2

Author(s):

J. L. Webb ◽

K. A. C. Elliott

Keyword(s):

Acetic Acid ◽

Oxygen Uptake ◽

Rat Brain ◽

Brain Tissue ◽

Acetyl Phosphate ◽

Fluoroacetic Acid ◽

Spontaneous Breakdown ◽

Acyl Phosphate ◽

Rat Brain Tissue

Observations have been made on methods for the determination of acetate and acyl phosphate in tissue suspensions. Previous work on the formation of acetate by respiring brain suspensions, especially in the presence of added pyruvate, has been confirmed. No evidence could be obtained that the substance formed is actually acetyl phosphate, which breaks down to yield acetic acid in the course of the estimation or enzymatically during the incubation of the tissue. The amount of acetate formed in brain suspensions is increased by the presence of malonate. It seems also to be increased by the addition of malate or α-ketoglutarate and by thiamine. Spontaneous breakdown of pyruvate could account for part of the acetate formed from pyruvate added to tissue. Fluoroacetic acid interferes with the determination of acetic acid. There was no evidence that it increases the formation of acetate by rat brain tissue suspensions. It does not affect the oxygen uptake of these suspensions with glucose or pyruvate as substrates.

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Ectodesmata as Revealed By Freeze-Etch Preparations of Plant Epidermal Cell Walls

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072782 ◽

1973 ◽

Vol 31 ◽

pp. 468-469

Author(s):

N.C. Lyon ◽

W. C. Mueller

Keyword(s):

Electron Microscopy ◽

Acetic Acid ◽

Nitric Acid ◽

Oxalic Acid ◽

Light Microscopy ◽

Epidermal Cell ◽

Cell Walls ◽

Plant Viruses ◽

Plant Leaves ◽

Thin Sections

Schumacher and Halbsguth first demonstrated ectodesmata as pores or channels in the epidermal cell walls in haustoria of Cuscuta odorata L. by light microscopy in tissues fixed in a sublimate fixative (30% ethyl alcohol, 30 ml:glacial acetic acid, 10 ml: 65% nitric acid, 1 ml: 40% formaldehyde, 5 ml: oxalic acid, 2 g: mecuric chloride to saturation 2-3 g). Other workers have published electron micrographs of structures transversing the outer epidermal cell in thin sections of plant leaves that have been interpreted as ectodesmata. Such structures are evident following treatment with Hg++ or Ag+ salts and are only rarely observed by electron microscopy. If ectodesmata exist without such treatment, and are not artefacts, they would afford natural pathways of entry for applied foliar solutions and plant viruses.

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