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At least 145 records · Page 8Linked to original sources
PubMed1984

Identification of methyl-branched chain dicarboxylic acids in amniotic fluid and urine in propionic and methylmalonic acidemia.

3-Methyladipic, 4-methylpimelic, 4-methylsuberic, pimelic, and azeleic acids were identified by gas chromatography-mass spectrometry in the amniotic fluid of fetuses with propionic acidemia. These compounds were virtually undetectable in normal amniotic fluid. Concentrations much higher than those of the amniotic fluid were found in the urine of neonatal infants with propionic acidemia and methylmalonic acidemia. It appears that the accumulation of these compounds is a consequence of the accumulation of propionyl-CoA. Evidence was obtained for the presence of other methyl-branched chain dicarboxylic acids. 4-Methylpimelic acid and 4-methylsuberic acid have not previously been identified in human physiological fluids.

Amniotic Fluid↗
PubMed1976

The effect of substitution of diaminopimelic acid by 4-hydroxy-diaminopimelic acid on the synthesis and degradation of murein in Escherichia coli 173-25.

Defects in the formation of the septum and gradually autolysis of cells occur when the dap-dependent mutant of Escherichia coli is grown in a medium with 4-hydroxy-diaminopimelic acid. When the culture grown in the presence of the labelled analogue is supplemented with the non-radioactive diaminopimelic acid a portion of the TCA-soluble radioactivity is released from the cells during 20 min after the addition of diaminopimelic acid. During this time interval the elongated forms formed in the presence of the analogue divide, however, only on the condition that the above forms are not irreversibly damaged. The increased concentration of the analogue in the medium substantially suppresses the irregularities in the development of the septum as well as the degradation of analogue containing cell wall. However, the growth rate in the presence of the analogue is always slightly lower than that in the presence of diaminopimelic acid. The cell wall pulse-labelled with diaminopimelic acid or its analogue for a time interval shorter than 1/4 of the generation time exhibits the same or only slightly higher rate of diaminopimelic acid is probably utilized less effectively for the synthesis of murein than diaminopimelic acid. However, its incorporation into the wall does not result in pronounced damage of the cell.

Cell Division↗
PubMed1977

Enzymic assays for isomers of 2,6-diaminopimelic acid in walls of Bacillus cereus and Bacillus megaterium.

An enzymic assay for individual isomers (meso-, LL- and DD-) of 2,6-diaminopimelate was developed. The enzyme 2,6-diaminopimelate decarboxylase specifically attacked meso-diaminopimelate and was used to measure this isomer manometrically. The meso- and LL-isomers were measured together manometrically in a coupled assay with diaminopimelate decarboxylase and diaminopimelate epimerase (which converts LL-diaminopimelate into meso-diaminopimelate). The DD-isomer was not attacked by either enzyme and was measured, as residual diaminopimelate after the coupled assay, by a colorimetric method, which was also used to measure total diaminopimelate before enzymic treatments. The coupled enzymes were also used to prepare pure DD-isomer from chemically synthesized diaminopimelate. A mixture of diaminopimelate isomers was present in walls of four strains of Bacillus megaterium [in each about 75% (w/w) meso-, 18% LL- and 7% DD-] and in walls of two strains of Bacillus cereus (about 85% meso-, 8% LL- and 7% DD-). One strain of B. cereus contained at least 95% meso-diaminopimelate, with only traces of LL- and DD-isomers. Peptidoglycan from Escherichia coli was assayed as containing at least 95% meso-isomer. The proportion of isomers in the wall of a strain of B. megaterium remained constant after growth in a variety of different media.

Amino Acid Isomerases↗
PubMed1978

A comparison of the action of glutamate, ibotenate and other related amino acids on feline spinal interneurones.

1. The effects of microiontophoretically applied glutamate, ibotenate and other related amino acids on the spike activity of feline spinal interneurones were investigated. 2. Unlike the other amino acids, which evoked excitatory responses only, ibotenate evoked slow biphasic responses (excitation-depression) from the majority of these neurones. The depressant action was associated with an increase in spike height and was reversible. 3. The ibotenate depression could be observed as a temporary reduction in background firing rate, a loss of sensitivity to other amino acids, a progressive decrease in the excitatory responses to repetitive ibotenate applications or a fading of excitation following a prolonged administration of ibotenate. 4. The onset of the excitatory effects of glutamate, quisqualate and ibotenate was relatively well fitted by diffusion equations for a continuous point source. However, radial distances for diffusion in the case of ibotenate responses were comparatively greater than those for glutamate and quisqualate. 5. The depressant action of ibotenate was not antagonized by strychnine, picrotoxin or bicuculline. 6. Some methods of quantifying the responses to excitatory amino acids are described. The excitatory potency of quisqualate and N-methyl-D-aspartate was several times greater than that of glutamate. Aspartate and ibotenate were equipotent, while alpha-aminopimelate and alpha-methyl-DL-aspartate were much weaker. 7. It is suggested that the biphasic action of ibotenate on spinal interneurones might be the result of activation of excitatory and inhibitory sites fairly remote from the cell somata where extracellular recordings were probably made.

Action Potentials↗
PubMed1973

Occurrence of glucosamine residues with free amino groups in cell wall peptidoglycan from bacilli as a factor responsible for resistance to lysozyme.

Analysis by dinitrophenylation techniques revealed the occurrence of significant amounts of glucosamine residues with free amino groups in the peptidoglycan component of cell walls isolated from Bacillus cereus, Bacillus subtilis, and Bacillus megaterium. A close correlation was demonstrated between the content of N-unacetylated glucosamine residues in the peptidoglycan component and the resistance of the cell walls to lysozyme. These lysozyme-resistant cell walls and peptidoglycan were converted into a lysozyme-sensitive form by means of N-acetylation with acetic anhydride. Thus, the occurrence of the N-unacetylated glucosamine residues in the peptidoglycan component accounts for the resistance of these cell walls to lysozyme. The N-unacetylated glucosamine residues were not found in a significant amount in the cell walls of Micrococcus lysodeikticus, Staphylococcus aureus, Streptococcus faecalis, Lactobacillus casei, or Lactobacillus arabinosus.

Alanine↗
PubMed1973

Effects of phagocytosis by rabbit granulocytes on macromolecular synthesis and degradation in different species of bacteria.

Phagocytosis and killing of gram-positive Bacillus megaterium and Micrococcus lysodeikticus by granulocytes in vitro is associated with almost immediate cessation of bacterial protein synthesis. By contrast, protein synthesis by Escherichia coli continues after ingestion and killing. After preincubation of E. coli with intact granulocytes for 15 min, when 95% or more of the bacteria can no longer multiply, induction of beta-galactosidase proceeds at rates about half of control values. With disrupted granulocytes, which kill E. coli as rapidly as intact cells, the rate of induction of beta-galactosidase does not fall until after 30 min of preincubation. We attribute the different effects of phagocytosis on the biochemical apparatus of these microorganisms to the different fates of their envelopes. Specifically labeled protein, ribonucleic acid, deoxyribonucleic acid, and lipid of all three species of bacteria and peptidoglycan of E. coli are apparently incompletely degraded during phagocytosis. However, the cell walls of M. lysodeikticus and B. megaterium undergo rapid and almost complete degradation. The resulting structural disintegration of these gram-positive microorganisms must cause extensive biochemical disorganization as well. Our evidence indicates that the E. coli envelope, on the other hand, retains sufficient structural organization to preserve integrated biochemical function for at least 1 h after the bacteria have lost the ability to multiply.

Animals↗
PubMed1974

Chemical characterization of organisms isolated from leprosy patients.

CHEMICAL ANALYSES OF THE CELL WALLS OF ORGANISMS ISOLATED IN VARIOUS PARTS OF THE WORLD FROM CASES OF LEPROMATOUS AND TUBERCULOID LEPROSY MAKE POSSIBLE THEIR ASSIGNMENT TO ONE OF THE THREE GENERA: Corynebacterium, Mycobacterium, or Propionibacterium. One, bacterium 22M, remains unassigned. The combined chemical and enzymatic properties attributed to leprosy bacilli freshly harvested from lepromata are found collectively, but not individually, in these three genera.

Amino Acids↗
PubMed1974

Subunit cell wall of Sulfolobus acidocaldarius.

The cell wall of Sulfolobus acidocaldarius has been isolated. Cells were mechanically disrupted with a French press, and the cytoplasmic membrane was removed by extracting cell-envelope fragments with Triton X-100. The Triton-insoluble cell wall material retained the characteristic subunit structure when examined in the electron microscope. Isolated cell wall fragments formed in open sheets that were easily separated from cytoplasmic contamination. Chemical studies showed that the Triton-insoluble cell wall fragments consisted of lipoprotein with small amounts of carbohydrate and hexosamine. The amino acid composition indicated a highly charged hydrophobic cell surface. The presence of diaminopimelic acid with only traces of muramic acid indicates that the cell envelope does not have a rigid peptidoglycan layer. The results of chemical analyses and electron microscopy suggest a wall-membrane interaction stabilizing the cell envelope. The chemical and physical properties of this type of cell envelope would appear to form the basis for a new major division of bacteria with the definitive characteristics of a morphologically distinct subunit cell wall devoid of peptidoglycan.

Amino Acids↗