PubMed Health⌕ Search

Biomedical subjects

H Reichenbach

Publications and source records attributed to H Reichenbach.

At least 73 records · Page 4Linked to original sources
PubMed1985

The mechanism of action of myxovalargin A, a peptide antibiotic from Myxococcus fulvus.

Myxovalargin A has two modes of action. At low concentrations (below 1 microgram/ml) it inhibits bacterial protein synthesis specifically and instantaneously. In vitro experiments suggest that it interferes with the binding of aminoacyl tRNA to the A site of the ribosome. At higher concentrations (above 5 micrograms/ml), or upon prolonged incubation, the antibiotic damages cell membranes. This leads to secondary effects, like decreased O2 consumption or instant break down of RNA synthesis, and may be the reason for the irreversibility of the antibiotic action. The membrane effect is not restricted to prokaryotes and may explain the high toxicity of the compound for higher organisms.

Animals↗
PubMed1985

The corallopyronins, new inhibitors of bacterial RNA synthesis from Myxobacteria.

From the culture broth of the myxobacterium, Corallococcus (Myxococcus) coralloides, three new antibiotics have been isolated: corallopyronin A, B and C. The compounds, which are chemically related to the recently discovered myxopyronins, act mainly on Gram-positive bacteria, with MIC values between 0.1 and 10 micrograms/ml, and only exceptionally or at much higher concentrations (MIC values; 100 and more micrograms/ml) on Gram-negatives. They do not inhibit eukaryotic organisms and show no toxicity for mice (sc). The corallopyronins appear to block specifically eubacterial RNA polymerase.

Animals↗
PubMed1984

Stigmatellin, a new antibiotic from Stigmatella aurantiaca (Myxobacterales). I. Production, physico-chemical and biological properties.

An antibiotic activity was extracted from the cell mass of the myxobacterium, Stigmatella aurantiaca strain Sg a15. The antibiotic was toxic for yeasts and filamentous fungi, but not for most bacteria. The compound had the molecular formula C30H42O7, appears to be a new antibiotic, and was named stigmatellin. In addition to stigmatellin, the strain produced relatively large quantities of a second, structurally unrelated antibiotic, a mixture of three myxalamid homologues.

Anti-Bacterial Agents↗
PubMed1983

The myxalamids, new antibiotics from Myxococcus xanthus (Myxobacterales). I. Production, physico-chemical and biological properties, and mechanism of action.

From the cell mass and culture supernatant of Myxococcus xanthus strain Mx X12 an antibiotic activity against yeasts, molds and some Gram-positive bacteria could be extracted. It consisted of 4 biologically active compounds which were named myxalamid A, B, C and D. The main component, myxalamid B, was shown to block in beef heart submitochondrial particles the respiratory chain at the site of complex I, i.e. NADH: ubiquinone oxidoreductase. The myxalamids are new antibiotics.

Animals↗
PubMed1983

The myxopyronins, new inhibitors of bacterial RNA synthesis from Myxococcus fulvus (Myxobacterales).

From the culture supernatant of the myxobacterium, Myxococcus fulvus strain Mx f50, an antibiotic activity was isolated which blocked growth of many Gram-positive and several Gram-negative bacteria, but not of yeasts and fungi. The activity consisted of two closely related compounds, myxopyronins A and B. The myxopyronins appear to be new antibiotics, and seem to specifically inhibit bacterial RNA polymerase.

Animals↗
PubMed1983

The myxovalargins, new peptide antibiotics from Myxococcus fulvus (Myxobacterales). I. Cultivation, isolation, and some chemical and biological properties.

Antibiotic activity was isolated from the culture supernatant of the myxobacterium Myxococcus fulvus strain Mx f65. It was active against Gram-positive bacteria (MIC 0.3 approximately 5 micrograms/ml), at higher concentrations also against Gram-negative ones (MIC 6 approximately 100 micrograms/ml), and not at all against yeasts and molds. The activity could be resolved into 4 closely related peptides, the myxovalargins. One of them, myxovalargin A, was by far the most plentiful. The compounds appear to be new antibiotics and seem to interfere with protein synthesis.

Anti-Bacterial Agents↗
PubMed1982

The myxovirescins, a family of antibiotics from Myxococcus virescens (Myxobacterales).

The myxobacterium, Myxococcus virescens strain Mx v48 produced a family of at least 12 closely related antibiotics, the myxovirescins. At a concentration of 1 to 5 micrograms/ml, the main component, myxovirescin A, was bactericidal for many Gram-negative bacteria, in particular enterobacteria, and at 20 to 50 micrograms/ml it also inhibited some pseudomonads and Gram-positive bacteria. The antibiotics seem to interfere with cell wall synthesis. The molecular formula of myxovirescin A was C35H61NO8. It is a new antibiotic.

Anti-Bacterial Agents↗
PubMed1981

Myxothiazol, a new inhibitor of the cytochrome b-c1 segment of th respiratory chain.

Myxothiazol inhibited oxygen consumption of beef heart mitochondria in the presence and absence of 2,4-dinitrophenol, as well as NADH oxidation by submitochondrial particles. The doses required for 50% inhibition were 0.58 mol myxothiazol/mol cytochrome b for oxygen consumption of beef heart mitochondria, and 0.45 mol/mol cytochrome b for NADH oxidation by submitochondrial particles. Difference spectra with beef heart mitochondria and with cell suspensions of Saccharomyces cerevisiae revealed that myxothiazol blocked the electron transport within the cytochrome b-c1 segment of the respiratory chain. Myxothiazol induced a spectral change in cytochrome b which was different from and independent of the shift induced by antimycin. Myxothiazol did not give the extra reduction of cytochrome b typical for antimycin. Studies on the effect of mixtures of myxothiazol and antimycin on the inhibition of NADH oxidation indicated that the binding sites of the two inhibitors are not identical.

Animals↗
PubMed1981

Myxothiazol, a new antibiotic interfering with respiration.

Myxothiazol, a new antibiotic from the myxobacterium Myxococcus fulvus, inhibited the growth of many yeasts and fungi at concentrations between 0.01 and 3 micrograms/ml. It was generally inactive against bacteria. The inhibitory effect was cytostatic. With Candida albicans, Saccharomyces cerevisiae, and Mucor hiemalis, the growth inhibition was neutralized by glucose. Soon after being added to a cell suspension, the compound almost completely blocked oxygen consumption.

Antifungal Agents↗
PubMed1978

Investigations of the pigments from Cytophaga johnsonae Cy jl. New flexirubin-type pigments.

Besides carotenoids a complex of flexirubin-type pigments was isolated from the gliding bacterium Cytophaga johnsonae Cy jl and separated into 6 components, which partly containe chlorine. In spite of the fact that these components still consist of pigment mixtures, the gross structures of 18 new flexirubin-type pigments could be deduced by spectroscopic and chemical investigations. The results open insights into biosynthesis and structural variety of the flexirubins, the novel non-isoprenoid pigments recently found in Flexibacter elegans.

Chemical Phenomena↗
PubMed1978

Intracellular location of flexirubins in Flexibacter elegans (Cytophagales).

The inner and outer membranes of 2 strains of Gram-negative Flexibacter elegans, Fx e1 and Fx 3/4, could be separated on sucrose density gradients after the cells had been converted into spheroplasts, and the spheroplasts had been lysed in presence of EDTA and the detergent Brij 58. The light fraction (rho = 1.14 g . cm-3) contained the components of the respiratory chain in high concentrations, but only low amounts of the lipopolysaccharide component, 2-keto-3-deoxyoctonic acid, and was thus mainly material from the inner membrane. The heavy fraction (rho = 1.175 g . cm-3) contained only traces of respiratory chain enzymes, but the majority of the 2-keto-3-deoxyoctonic acid, and was thus mainly material from the outer membrane. The flexirubin pigments were found almost quantitatively in the latter fraction. Strain Fx 3/4 produced carotenoids in addition to flexirubins; in this case the flexirubins were located in the outer, and the carotenoids in the inner membrane.

Bacteroidetes↗
PubMed1978

Restriction endonucleases: general survey procedure and survey of gliding bacteria.

Among 120 strains of gliding bacteria which were screened for restriction endonucleases, 27 were found positive. Additionally, three strains carried enzymes able to release the supercoiled state of closed circular DNA. By using a new rapid method, restriction endonuclease activity was released by stirring about 0.5 g of cells (fresh weight) in a motor-driven glass homogenizer in buffer containing Triton X-101, ethylenediaminetetraacetic acid, and mercaptoethanol. A yield from 60 to 80% of the total activity present in the cells was obtained with minimal destruction of the cells. The enzyme activity in the crude extract was measured semi-quantitatively by digestion of DNA and subsequent separation of the fragments on an agarose slab gel. The method appears to be generally applicable for the extraction of restriction endonucleases from gram-negative bacteria on an analytical scale and in a modified form for large-scale preparation of restriction enzymes.

Coliphages↗
PubMed1977

Carotenoid glucosides and menaquinones from the gliding bacterium Herpetosiphon giganteus Hp a2.

The gliding bacterium Herpetosiphon giganteus Hp a2 was shown to contain gamma-carotene, one monoglucosyloxy and two new diglucosyloxy carotenoids with a x-O-acyldiglucosyloxy carotenoid as main component. Flexirubin-like pigments could not be detected in this organism. As in the Myxobacterales and Cytophagales (Kleinig et al., 1974) menaquinones (MK-6 and MK-7) were found to be the only isoprenoid quinones present in Herpetosiphon. The chemosystematic implications of these findings are briefly discussed.

Bacteroidetes↗