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Biomedical subjects

G Winkelmann

Publications and source records attributed to G Winkelmann.

At least 73 records · Page 4Linked to original sources
PubMed1984

Activity of herbicolin A against Mycoplasma, Acholeplasma, Ureaplasma, and Spiroplasma species.

Herbicolin A, a novel acyl peptide antibiotic, inhibits the growth of the sterol-requiring Mycoplasma, Ureaplasma, and Spiroplasma species, with MICs varying from 1.5 to 100 micrograms/ml. With the exception of Acholeplasma modicum, all of the non-sterol-requiring species of the family Acholeplasmataceae were totally resistant to herbicolin A when tested on serum-containing medium but were inhibited to some extent on medium devoid of serum and any other source of sterol or fatty acids.

Acholeplasma↗
PubMed1983

Iturin AL--a new long chain iturin a possessing an unusual high content of C16-beta-amino acids.

From a strain of Bacillus subtilis a new antifungal peptidolipid complex of the iturin group was isolated. This antibiotic complex contained six lipophilic beta-amino acids with 3-amino-14-methylpentanoic acid as the predominant component. Iturin AL contains: 2 D-Asp, 1 L-Asp, 1 L-Glu, 1 L-Pro, 1 L-Ser, 1 D-Tyr and a mixture of 2.9% iso-C14-beta-amino acid, 30.7% n-C14-beta-amino acid, 15% iso-C15-beta-amino acid, 9% anteiso-C15-beta-amino acid, 35.3% iso-C-16-beta-amino acid and 4.5% n-C16-beta-amino acid. The structures of the beta-amino acids were determined by combined GLC/MS. FAB mass spectroscopy revealed three M+H+ peaks (1,043, 1,057, 1,071). Iturin AL could be resolved into six components by HPLC whose structures confirm the high amount of long chain beta-amino acids.

Amino Acids↗
PubMed1980

Herbicolins--New peptide antibiotics from Erwinia herbicola.

Erwinia herbicols (strain A 111) produces two acylated peptide antibiotics herbicolins A and B. Isolation of herbicolins was performed by adsorption on a polystryrol adsorbent followed by elution with methanol. Further purification was achieved by gel filtration on Sephadex LH-20, counter-current distribution or by TLC. Herbicolin A was chemically characterized, containing 2 glycines, 1 L-threonine, 1 D-allo-threonine, 1 D-glutamic acid, 1 D-leucine, 1 L-agrinine and beta-hydroxy myristic acid. Herbicolins A and B are inactive against bacteria, but highly active against yeasts and filamentous fungi.

Anti-Bacterial Agents↗
PubMed1978

Iron uptake studies on erythroid cells.

Iron uptake from 55Fe-labelled transferrin, ferric citrate and the two fungal sideramines, ferricrocin and fusigen was studied using four erythroid cell cultures: Friend virus-transformed erythroleukemic cells (mouse), transformed bone marrow cells, Detroit-98 (human), reticulocytes (bovine), bone marrow cells (rabbit). The present comparative study reveals pronounced differences in iron uptake behaviour. Compared to transferrin, ferric citrate and the sideramines are preferred in transformed erythroid cells. In reticulocytes transferrin and ferric citrate showed a better uptake as compared to the two sideramines. Primary bone marrow cells showed nearly equal iron uptake rates using transferrin or ferricrocin.

Animals↗
PubMed1978

Use of iron from transferrin and microbial chelates as substrate for heme synthetase in transformed and primary erythroid cell cultures.

The enzymatic heme production in cell-free extracts of virus-transformed Friend erythroleukemia cells and primary bone marrow cells from rabbits has been measured by determining the activity of heme synthetase after addition of iron sulfate, transferrin or microbial iron chelates. In transformed cells the amounts of heme formed did not show significant difeerences independent of which substrate was offered. In cell-free extracts of primary bone marrow cells no increase of heme production could be observed.

Animals↗
PubMed1977

Enzymatic release of iron from sideramines in fungi. NADH:sideramine oxidoreductase in Neurospora crassa.

Young mycelia of the fungus Neurospora crassa contain a soluble NADH-linked sideramine reductase, which may be responsible for liberating iron in vivo from accumulated sideramines during iron-deficient cultivation. The enzymes can be assayed using a soluble supernatant fraction, EDTA, and an atmosphere of pure nitrogen. The enzyme is stable without loss of activity up to 45 degrees C and has an optimum of activity at pH 7.0. Besides coprogen (Km = 100 micrometer, V=2.8 nmol/min per mg protein), some other ferrichrome-type compounds are reduced. However, ferrichrome, ferrirubin coprogen B and ferrioxamine are poor substrates. When the mucelia were grown in a medium containing 10(-5) M ferri iron, the activity of the reductase was found to be only 30% of that found under low iron conditions. The enzyme is inhibited by oxygen, SH-alkylating agents and partly by some detergents. Unlike the reductase of N. crassa, the corresponding enzyme from Aspergillus fumigatus revealed low reduction of coprogen and high reduction of ferrichrome, indicating genusdependent specificities of sideramine reduction enzymes in fungi. The participation of acids of the citric acid cycle as natural iron acceptors during strong iron deficiency is studied and confirmed by iron uptake measurements on isolated mitochondria.

Adenosine Triphosphate↗
PubMed1976

Microbial iron chelates with iron donor properties in hemoglobin-synthesizing cells.

Iron incorporation into Friend virus infected leukemic murine spleen cells was studied using the two fungal iron trihydroxamates, fusigen and ferricrocin. Incorporation of 55Fe was measured by isolation of hemoglobin after dimethylsulfoxide-induced hemoglobin synthesis and compared with iron incorporation from 55Fe-labeled ferric citrate.

Animals↗
PubMed1975

Kinetic studies on the specificity of chelate-iron uptake in Aspergillus.

Three strains of the fungus Aspergillus, Aspergillus quadricinctus (E. Yuill), A. fumigatus (Fresenius), and A. melleus (Yukawa), each producing different iron-chelating compounds during iron-deficient cultivation, were used for 55Fe3+ uptake measurements. Iron from chelates of the ferrichrome-type family was taken up by young mycelia of all strains tested, irrespective of the ferrichrome-type compound these strains predominantly produce in low-iron cultures. Ferrichrysin-producing strains, however, seem to favor ferrichrysin iron uptake, whereas ferrichrome, ferricrocin, and even ferrirubin showed similar iron transport properties in all of these strains. Compared to iron uptake from ferrichrome-type compounds (Km approximately 4 uM) iron uptake from fusigen revealed completely different kinetic values (Km approximately 50 to 80 muM). Iron from exogenous chelates, e.g., from coprogen produced by Neurospora crassa for ferrioxamine B produced by Streptomyces pilosus, can obviously not be taken up by Aspergillus, confirming the pronounced specificity of chelate-iron transport in fungi.

Aspergillus↗