| 363352 |
Amatoxins, phallotoxins, phallolysin, and antamanide: the biologically active components of poisonous Amanita mushrooms |
10.3109/10409237809149870. |
CRC Crit Rev Biochem |
Amatoxins, phallotoxins, phallolysin, and antamanide: the biologically active components of poisonous Amanita mushrooms
Abstract
- This review gives a comprehensive account of the molecular toxicology of the bicyclic peptides obtained from the poisonous mushrooms of the genus Amanita. The discussion of the biochemical events will be preceded by a consideration of the chemistry of the toxic peptides. The structural features essential for biological activities of both the amatoxins and the phallotoxins will be discussed, also including the most important analytical data. Similar consideration will be given to antamanide, a cyclic peptide, which counteracts phalloidin. In addition, the phallolysins, three cytolytic proteins from Amanita phalloides will be discussed. The report on the biological activity of the amatoxins will deal with the sensitivity of the different RNA-polymerases towards the toxins and with their action on various cell types. Consideration will also be given to systems in which alpha-amanitin was used and can be used as a molecular tool; in the past, many investigators used the inhibitor in molecular biology, genetics, and even in physiological research. As for the phallotoxins, discussion of the affinity of these toxins for actin is provied. Further discussion attempts to understand the course of intoxication by filling in the gap between the first molecular event, formation of microfilaments, and the various lesions in hepatocytes during the intoxication.
|
| 385320 |
Iron supply of Escherichia coli with polymer-bound ferricrocin |
10.1111/j.1432-1033.1979.tb13228.x. |
Eur J Biochem |
Iron supply of Escherichia coli with polymer-bound ferricrocin
Abstract
- Uptake of ferric iron from ferricrocin was studied in Escherichia coli using a polymer-coupled ferricrocin that was unable to penetrate into the cell. Ferricrocinyl polyethylene glycol succinate (Mr 7000 -- 8500) promoted growth of E. coli K-12 AB2847 aroB under iron-limiting conditions. In iron-starved cells, uptake of 55Fe could be demonstrated; the amount of iron accumulated amounted to 10% of that observed with free ferricrocin. The iron supply by ferricrocin bound to polyethylene glycol was strictly dependent upon the functions expressed by the tonA and the tonB genes, as was the iron uptake promoted by free ferricrocin. Polymer-bound ferricrocin protected cells against colicin M and phage T5 by competition for the common tonA-coded outer membrane receptor protein. In addition, the rate of iron transport via the negatively charged ferricrocinyl succinate was as fast as via the neutral ferricrocin molecule. No ligand was found associated with the cells. Penetration of chelator beyond receptor is not necessary for siderophore-mediated iron uptake. It is concluded that sufficient amounts of iron can be released from the polymer complex to satisfy growth requirements.
|
| 391799 |
Existence of the bound form of prolipoprotein in Escherichia coli B cells treated with globomycin |
10.1128/jb.140.3.1098-1101.1979. |
J Bacteriol |
Existence of the bound form of prolipoprotein in Escherichia coli B cells treated with globomycin
Abstract
- A murein-bound form of prolipoprotein was found in the cell envelope fraction of globomycin-treated Escherichia coli B. We suggest therefore that proteolytic cleavage of prolipoprotein to mature lipoprotein is not essential for the transpeptidation of the lipoprotein to peptidoglycan.
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| 395066 |
D-Trp8-D-Cys14-somatostatin--demonstration of its differential suppressive activity in juvenile diabetics |
None |
Horm Metab Res Suppl |
D-Trp8-D-Cys14-somatostatin--demonstration of its differential suppressive activity in juvenile diabetics
Abstract
- In 8 insulin-dependent diabetics, the effect of D-Trp8-D-Cys14-somatostatin on blood glucose, growth hormone, and glucagon levels as well as on insulin requirements from an artificial endocrine pancreas was studied during a balanced meal. The somatostatin analogue was infused at a rate of 25 microgram/h preceeded by a bolus injection of 25 microgram 30 minutes before ingestion of the meal. At this dose the analogue had no effect on glucagon levels and insulin requirements from the artificial pancreas. On the other hand, there was a significant lowering effect on fasting blood glucose levels, possibly indicating a direct inhibition of hepatic glucose production. Furthermore, there might be a slight effect on growth hormone levels, as was demonstrated by a rebound increase after termination of analogue infusion.
|
| 418374 |
Virginiamycin resistance in staphylococci (author's transl) |
None |
Pathol Biol (Paris) |
Virginiamycin resistance in staphylococci (author's transl)
Abstract
- Virginiamycin M factor transformation into an o-acetyl derivative has been observed in a particular Staphylococcus strain, naturally resistant to virginiamycin (Vr). It could not be detected in induced strains nor in sensitive ones. Turbidimetric studies with the naturally resistant strain showed that increasing concentration of the antibiotic had a progressive prolongation effect on the lag phase, without change in the growth rate. The prolonged lag phase could be reduced or eliminated by using an inoculum of cells previously "adapted" to M factor or virginiamycin. Preadapted cells had an increased acetylating power. Acridine dye treated cells showed a decreased o-acetyl derivative formation. This all suggested that virginiamycin resistance in the particular Vr strain was effectively connected with o-acetylation of the M factor.
|
| 488361 |
NMR saturation transfer and line shape analyses of cyclic tetradepsipeptide AM toxin II: conformational equilibrium with very unequal populations |
10.1016/0014-5793(79)80643-2. |
FEBS Lett |
NMR saturation transfer and line shape analyses of cyclic tetradepsipeptide AM toxin II: conformational equilibrium with very unequal populations
Abstract
|
| 540211 |
Drug or milieu? |
10.1192/bjp.135.5.481b. |
Br J Psychiatry |
Drug or milieu?
Abstract
|
| 555036 |
Induction of labor by oral administration of desamino-oxytocin |
None |
Riv Ital Ginecol |
Induction of labor by oral administration of desamino-oxytocin
Abstract
|
| 569011 |
Effects of Bouvardin (NSC 259968), a cyclic hexapeptide from Bouvardia ternifolia, on the progression capacity of cultured Chinese hamster |
None |
Cancer Res |
Effects of Bouvardin (NSC 259968), a cyclic hexapeptide from Bouvardia ternifolia, on the progression capacity of cultured Chinese hamster
Abstract
|
| 573901 |
Distribution, survival and biological effects in mice of a behaviorally active, enzymatically stable peptide: pharmacokinetics of cyclo(Leu-Gly) and puromycin-induced amnesia |
10.1016/0091-3057(79)90334-4. |
Pharmacol Biochem Behav |
Distribution, survival and biological effects in mice of a behaviorally active, enzymatically stable peptide: pharmacokinetics of cyclo(Leu-Gly) and puromycin-induced amnesia
Abstract
- Cyclo(Leu-Gly), the enzymatically resistant diketopiperazine formally derived from the C-terminal dipeptide sequence of oxytocin, exhibits activity in several behavioral systems. The distribution of cyclo(Leu-14C(U)Gly) in brain, and the time course of the disappearance of this labeled peptide from brain and plasma after subcutaneous injection into mice have been studied. The intact peptide was distributed equally in the five cerebral areas studied, for up to 96 hours after injection. Two exponential components were determined for peptide disappearance rates in plasma and brain; peptide half-lives in plasma up to 10 hr and from 24--96 hr after injection were, respectively, 0.8 and 33 hr; in brain, 1.0 and 42 hr. The peptide was found to accumulate in brain intracellular space to some degree. The time course of distribution of labeled cyclo(Leu-Gly) in subcellular fractions of mouse brain was also examined, and the concentration of peptide in the synaptosomal fraction was significantly correlated with the degree of protection against puromycin-induced amnesia of a maze-learning test. The results obtained not only confirm that cyclo(Leu-Gly) penetrates brain tissue intact and remains intact after peripheral administration in order to exert its behavioral effects, but, moreover, suggest an intriguing dynamic relationship between peptide concentration in the synaptosomal fraction and behavioral activity.
|
| 576069 |
In vivo effect of deamino-oxytocin on rat intraovarian pressure and its relationship to the estrous cycle |
None |
Acta Physiol Lat Am |
In vivo effect of deamino-oxytocin on rat intraovarian pressure and its relationship to the estrous cycle
Abstract
|
| 591465 |
Studies on mycobacillin derivatives. IV. O-methylation of the antibiotic and identification of the active tyrosine residue |
10.7164/antibiotics.30.987. |
J Antibiot (Tokyo) |
Studies on mycobacillin derivatives. IV. O-methylation of the antibiotic and identification of the active tyrosine residue
Abstract
- Methylation of myocobacillin with dimethyl sulfate and methyl iodide produced respectively mono- and di-methyl derivatives. the products were inactive against fungal spores and erythrocytes. Tyrosine hydroxyl groups only were methylated; in the monomethyl derivative, the hydroxyl of the tyrosine residue in position 6 is methylated, whereas the hydroxyl of the tyrosine in position 4 remains free; both hydroxyl groups are methylated in the dimethyl derivative. The results indicate that the hydroxyl group of the tyrosine residue in position 6 is essential for the biological activity of mycobacillin.
|
| 658439 |
Action of mycosubtilin and of bacillomycin L on Micrococcus luteus cells and protoplasts: influence of the polarity of the antibiotics upon their action on the bacterial cytoplasmic membrane |
10.1016/0014-5793(78)80292-0. |
FEBS Lett |
Action of mycosubtilin and of bacillomycin L on Micrococcus luteus cells and protoplasts: influence of the polarity of the antibiotics upon their action on the bacterial cytoplasmic membrane
Abstract
|
| 664074 |
Desaminooxytocin induced labor and neonatal hyperbilirubinemia. A prospective study |
None |
Ugeskr Laeger |
Desaminooxytocin induced labor and neonatal hyperbilirubinemia. A prospective study
Abstract
|
| 677874 |
Production of cyclochlorotine and a new metabolite, simatoxin, by Penicillium islandicum Sopp |
10.1128/aem.35.6.1074-1078.1978. |
Appl Environ Microbiol |
Production of cyclochlorotine and a new metabolite, simatoxin, by Penicillium islandicum Sopp
Abstract
- Production of the hepatotoxin cyclochlorotine by Penicillium islandicum was studied under a variety of fermentation conditions. The best system for production was agitated red wheat. A thin-layer chromatographic method was developed for the detection of this cyclic polypeptide. These experiments have resulted in the isolation of a new toxic metabolite, which we call simatoxin.
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