Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CEPHALOSPORIUM”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources
PubMed1991

The functional role of cysteines in isopenicillin N synthase. Correlation of cysteine reactivities toward sulfhydryl reagents with kinetic properties of cysteine mutants.

Isopenicillin N synthase (IPNS) from Cephalosporium acremonium contains 2 cysteine residues in positions 106 and 255 which are invariant in all IPNS sequences reported to date (Miller, J.R., and Ingolia, T.D. (1989) Mol. Microbiol. 3, 689-695). Although these residues have been postulated to play a role in catalysis (Samson, S.M., Chapman, J.L., Belagaje, R., Queener, S., and Ingolia, T.D. (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 5705-5709) as well as enzyme inactivation (Perry, D., Abraham, E.P., and Baldwin, J.E. (1988) Biochem. J. 255, 345-351) little information exists regarding their oxidation state and reactivity. In this paper, the functions of these cysteines have been addressed by chemical modification techniques in combination with site-directed mutagenesis. In the intact wild type protein, both cysteines are inert toward 5,5'-dithiobis-(2-nitrobenzoic acid) and iodoacetic acid. However, Cys-106, but not Cys-255, can be slowly modified by N-ethylmaleimide, and its modification is partially blocked by the presence of a substrate analog inhibitor. Complete modification of both cysteines by sulfhydryl reagents requires unfolding of the protein but not the presence of a disulfide reducing agent. The thiol content of IPNS is shown to be the same before and after exposing the enzyme to substrate even though during catalysis the enzyme is rapidly inactivated. The impact on catalysis due to alteration of the cysteines has been assessed using three site-specific mutants: Cys-106----Ser, Cys-255----Ser, and Cys-106,255----Ser. These mutant proteins have been purified as apoenzymes with the nature of the mutation verified by peptide mapping. The stoichiometry of metal required for activity remains as one equivalent of Fe2+/mol of enzyme in the mutants as in wild type IPNS. Compared with wild type, Cys-255----Ser shows a reduction in Vmax by 33%, and an increase in Km by 1.4-fold, while Cys-106----Ser and Cys-106,255----Ser, which have identical kinetic properties, exhibit a decrease in Vmax by 63% but an elevation of Km by 14-fold. The data presented demonstrate that 1) both cysteines are free thiols; 2) Cys-106 is more exposed than Cys-255; 3) substrate-induced inactivation is not caused by cysteine modification; 4) neither cysteine is absolutely essential for bond making or breaking events during catalysis.(ABSTRACT TRUNCATED AT 400 WORDS)

Acremonium↗
PubMed1990

Regulation of ACV synthetase: biosynthesis and action.

The biosynthesis of cephalosporins has been studied for almost 30 years. Development of cell-free systems began with the later enzymes of the pathway and, in recent years, moved to the early part of the pathway. The first enzyme, delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine (ACV) synthetase was one of most difficult to demonstrate in cell-free extracts. We recently developed a reproducible system from Cephalosporium acremonium (Banko et al., 1987) and similar activity has been found in Streptomyces clavuligerus (Jensen et al., 1988). With this assay, we have been able to study the regulation of ACV synthetase formation and action. Our results are summarized in this communication. Our comparison of the intracellular specific activities of the beta-lactam synthetases in both C. acremonium c-10 and S. clavuligerus NRRL 3585 indicates that ACV synthetase possesses the lowest activity and appears to be the rate-limiting step in the cephalosporin biosynthetic process. Since it is the initial enzyme in the biosynthetic pathway common to both penicillins and cephalosporins, this makes sense from a cellular economy viewpoint. It is therefore understandable that ACV synthetase would be subject to greater regulatory control than other steps.

Acremonium↗
PubMed1990

Keratomycoses in Viet-Nam.

In Viet-Nam the incidence of keratomycoses is increasing up to recent years. The role of subtropical climate and environmental conditions is pointed out. Among the causative fungi Aspergillus, Cephalosporium and fungi imperfecti are the most frequent, as opportunistic agents. Some clinical aspects are described, and the peculiar severity in evolution stressed on. In the absence of specific antifungal drugs, another method of management, using potassium iodide associated with Griseofulvin and auto-serum is proposed, while keratoplasty with full-thickness corneal graft during the active process may be indicated. These procedures permitted to save a notable number of eyes from total blindness or enucleation.

Corneal Diseases↗
PubMed1989

Spectroscopic studies of isopenicillin N synthase. A mononuclear nonheme Fe2+ oxidase with metal coordination sites for small molecules and substrate.

The nonheme iron oxidase isopenicillin N synthase catalyzes the formation of two new internal bonds in the tripeptide delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-valine (ACV) to form the beta-lactam and thiazolidine rings of isopenicillin N. Concomitantly, O2 is reduced to 2 H2O. The recombinant enzyme from Cephalosporium acremonium (Mr = 38,400), expressed as an apoenzyme in Escherichia coli, binds 1 g atom of Fe2+/mol of enzyme to reconstitute full activity. Mössbauer spectra of the 57Fe-enriched enzyme exhibit parameters (delta = 1.30 mm/s, delta EQ = 2.70 mm/s) which unambiguously show that the active site iron is high spin Fe2+. Anaerobic binding of ACV causes a substantial decrease in the isomer shift parameter delta (delta = 1.10 mm/s, delta EQ = 3.40 mm/s) showing that the substrate perturbs the iron site and makes its coordination environment much more covalent. Nitric oxide (NO) binds to the EPR silent active site iron to give an EPR active species (g = 4.09, 3.95, 2.0; S = 3/2) similar to those of the nitrosyl complexes of many other mononuclear Fe2+-containing enzymes. The rhombicity of the EPR spectrum is increased (g = 4.22, 3.81, 1.99) by anaerobic addition of ACV suggesting that the substrate binds to or near the iron without displacing NO. Interestingly, the enzyme.ACV.NO complex displays an optical spectrum similar to that of ferric rubredoxin in which the iron has only thiol coordination. This suggests that the Fe2+ of the enzyme.ACV.NO complex acquires Fe3+ character and that the cysteinyl thiol moiety of ACV coordinates to the iron. Similar substrate thiol coordination to the iron of the enzyme.ACV complex is the most probable explanation for the large decrease in isomer shift observed. These results provide the first evidence for the direct involvement of iron in this unique O2-dependent reaction and suggest novel roles for iron and oxygen in biological catalysis.

Acremonium↗
PubMed1989

Synthesis of some pyrazoline and isoxazolin derivatives as possible fungicides.

1-Acetyl/aroyl-3-methyl-4-substituted anilido-5-aryl pyrazolines and 3-methyl-4-substituted anilido-5-aryl isoxazolines were conveniently prepared from synthon, 4-aryl-3-substituted anilido but-3-en-2-ones in presence of hydrazine hydrate/hydrazides and hydroxylamine hydrochloride respectively. All the compounds have been assayed against Cephalosporium sacchari and Helminthosporium oryzae and found remarkably active. Two species of aquatic fungi viz. Saprolegnia parasitica and Achlya orion responsible for fish mycoses were tested and also found remarkably active.

Antifungal Agents↗
PubMed1989

[Presence of potentially pathogenic bacteria and fungi in the cooling-lubricating emulsion used in the aluminum sheet rolling process].

Microbiological tests of aluminium rolling water-oil emulsion reveal high level of contamination: relatively anaerobic bacteria 10(6)-10(8) cells/ml, fungi and yeasts 10(3)-10(4) cells/ml, and also anaerobic bacteria Desulfovibrie sp. reducing sulfates to hydrogen sulfide. In emulsion samples there were present bacterial strains potentially dangerous to health, belonging to the family Enterobacteriaceae, Vibrionaceae, Pseudomonadaceae, Bacillaceae. The fungi and yeasts found in the emulsion were identified as: Aspergillus sp., Penicillium sp., Cladosporium sp., Cephalosporium sp., Candida sp. The emulsion sprayed in aerosol in air of the mill was the infecting source for the workers. The emulsion was protected by a biocid and thus the growth of potentially pathogenic microorganisms was inhibited.

Aluminum↗
PubMed1988

Factors affecting the isopenicillin N synthetase reaction.

1. Isopenicillin N synthetase (IPNS) from Cephalosporium acremonium, which requires Fe2+ and O2 for activity, was highly purified for studies of factors affecting its conversion of delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-valine (LLD-ACV) into isopenicillin N (IPN). EDTA was used to quench the reaction by removal of Fe2+. 2. IPNS was inactivated during the course of the conversion of LLD-ACV into IPN, although it was relatively stable in the absence of LLD-ACV under otherwise similar conditions. In the presence of GSH and ascorbate each IPNS molecule carried out about 200 catalytic events before inactivation, but the turnover number was decreased 5-fold in the absence of ascorbate. 3. After trace metal ions had been removed from IPNS and other components of the reaction mixture by Chelex-100 resin, only about 10 microM-Fe2+ was required for maximum stimulation. Several other transition-metal ions were inhibitors of the enzyme. 4. Both dithiothreitol (DTT) and GSH stimulated IPNS activity, but GSH, unlike DTT, was not rapidly oxidized in the presence of O2 and Fe2+. 5. IPNS was rapidly inhibited by the thiol-blocking reagents N-ethylmaleimide and 2,2'- and 4,4'-dipyridyl disulphide, but not by 5,5'-dithiobis-(2-nitrobenzoic acid) in the same concentration. Inhibition by 2,2'-dipyridyl disulphide could be reversed by DTT.

Acremonium↗
PubMedDate not supplied

[Enzyme preparations for research on protein hydrolysates and amino acid mixtures not containing peptides].

Some properties and the hydrolysing ability of two novel enzyme preparations, a proteolytic preparation "C" from Acremonium chrysogenum (Cephalosporium acremonium) and a peptidase preparation (the producer from the family Pseudomanadaceae), are described. The preparations can be used for obtaining protein hydrolysates with different ratios of free amino acids and peptides. The protein hydrolysis with the preparation "C" enables one to obtain hydrolysates containing 13-18% of free amino acids. The further treatment of the hydrolysates with the peptidase preparation results either in complete hydrolysis of the remained peptide fractions or in obtainment of solutions containing from 60 to 85% of free amino acids and low-molecular weight peptides.

Amino Acids↗
PubMed1985

Control of cell division by aphidicolin without adverse effects upon resting cells.

Aphidicolin, a tetracyclic diterpenoid obtained from the culture filtrates of Cephalosporium aphidicola and other fungi, inhibits the growth of eukaryotic cells and of certain animal viruses (SV40, Herpes and Vaccinia viruses) by selectively inhibiting the cellular replicative DNA polymerase alpha or the viral-induced DNA polymerases. The arrest of cellular or viral growth is thus due to inhibition of cellular or viral replicative DNA synthesis without interference with mitochondrial DNA synthesis, RNA, protein and nucleic acid precursors synthesis or other major metabolic pathways. The inhibition of all sensitive eukaryotic DNA polymerases by aphidicolin is competitive with respect to dCTP. Aphidicolin has thus proved extremely useful in elucidating the functional role of DNA polymerase alpha in nuclear DNA replication, of DNA polymerase gamma in mitochondrial DNA synthesis and both DNA polymerases beta and alpha in DNA repair synthesis. An important laboratory application of aphidicolin is the synchronization of the cell cycle of eukaryotic cells both in culture and in vivo. The properties of aphidicolin have recently aroused considerable interest for its possible exploitation in al practice. The mechanism of action of this drug suggests in fact that it may be useful for controlling excessive cell proliferation in patients with cancer, psoriasis or other dermatitis with little or no adverse effect upon non-multiplying cells. Interestingly, when administered to mice, the highest levels of aphidicolin are found in those tissues most actively proliferating with little or no aphidicolin present in neurons or myocardial cells.

Animals↗
PubMed1979

Fungal invasion of a therapeutic soft contact lens and cornea.

A fungal corneal infection occurred in a 66-year-old man who wore a therapeutic soft contact lens for 12 months during treatment for a metaherpetic corneal epithelial erosion. The infection was documented by finding positive cultures from both the contact lens and the cornea, and histologic evidence of fungal infiltration of the therapeutic soft lens. The fungus was identified as Cephalosporium acremonium. Pathogenic fungal invasion of soft lenses is unusual. Corneal infections associated with such conditions are rare. This case demonstrates histologically, a pathogenic fungal corneal infection arising from therapeutic contact lens wear. Factors that may influence soft lens infiltration by fungi are: (1) enzymatic activity produced by the fungus, and (2) lens material properties which provide a matrix and a nutrient source for fungal growth. Continuous-wear soft contact lens treatment with topical steroid and prophylactic antibiotics used in combination in an already compromised cornea were thought to be responsible in an already compromised cornea were thought to be responsible for this complication. A therapeutic penetrating keratoplasty was performed when the infection and its accompanying inflammation became clinically unresponsive to multifold therapy, and a corneal perforation was imminent. The eye was salvaged with a resulting clear graft and stable intraocular pressures.

Acremonium↗
PubMed1979

Incidence of Fusarium moniliforme Sheld. in Zea mays L. in the rainforest zone of Nigeria.

45 seed samples from 7 states of the rainforest zone of Nigeria (Ogun, Ondo, Oyo, Bendel, Anambra, Imo, and Cross River) were screened for phytopathogen incidence. Whereas Drechslera maydis was found in 30 and Cephalosporium maydis in 79% of the samples were infected by Fusarium moniliforme, with 70% of the samples showing heavy infection. In view of the widespread nature of this economically important fungus on maize in the main cultivation area of Nigeria, the necessity for routine laboratory seed health tests is clearly indicated.

Animals↗
PubMed1979

Subchronic toxicity test for two thermotolerant filamentous fungi used for single cell protein production.

Safety evaluations of two thermotolerant filamentous fungi, Cephalosporium eichhorniae 152 (C. 152) and Rhizopus chinensis 180 (R. 180), grown on a sugar-salts medium were carried out through feeding the biomases to rats at 20% or 40% dietary levels for 90 days. There was a control group fed soybean meal. Weight gain and feed consumption for rats fed 20% C. 152 were equal to those for the control animals, but were depressed in the other three groups, especially the rats fed R. 180. All animals appeared normal and healthy except that transient alopecia was found for a short duration in the fungi-treated rats in the initial period. The cause of this lesion is not clear. At the end of the feeding trial, clinical determinations of constituents in blood and urine samples were conducted. The animals were autopsied and weights for four organs were taken. Histopathological examinations for 26 different tissues were carried out. Mild changes were found in both C. 152 and R. 180-treated rats but most of the these were not considered to be related to treatment.

Acremonium↗
PubMed1981

[Mycosis of the foot in people over 40].

Some aspects of the ecology of the human foot in the stage of senescence have been studied. Systematically 200 hospitalized patients, chosen at random, between the ages of 40 and 96 years were examined. The following was observed: 1.) 133 patients (66,5%) presented lesions suspected as dermatomycoses. 2.) 67 patients (33,5%) were free from clinical lesions. 42 (31,5%) positive direct examinations were obtained from the first group and 8 (11,8%) from the second one. In culture were isolated different strains of Dermatophytes obtained from 50 patients as follows: a) From digital fold scales: Trichophyton mentagrophytes: 26 (v. granulosa: 9. v. gypsea: 16, v nivea: 1). Trichophyton rubrum: 18, Epidermophyton floccosum: 1. b) From toe nails: Trichophyton mentagrophytes v. granulosa: 3, Trichophyton rubrum: 7. c) From the sole: Trichophyton rubrum: 1. A series of fungi supposed contaminants were isolated among which because of frequency the following are specified: Aspergillus sp., Penicillium sp., Cephalosporium sp., Fusarium sp., some yeast and some Demataceae.

Adult↗
PubMed1995

Biophysical factors affecting the expression of isopenicillin N synthase isozymes in Escherichia coli.

The influence of biophysical factors over the production of isozymes of isopenicillin N synthase (IPNS) from fungal and bacterial sources in Escherichia coli was examined. The effect of these parameters on the expression of Cephalosporium acremonium IPNS was determined by using two expression vectors containing the lac- or the T7-promoter. Under the lac-promoter, IPNS expressed in E. coli reached 5-15% of total soluble proteins and under the T7 promoter, the level reached approximately 50% of total soluble proteins. Furthermore the high level of expression did not affect aggregation of IPNS proteins. Analysis of the hydrophobicity of the C. acremonium IPNS and site-specific mutant enzymes relative to other IPNS isozymes suggested that proteins of low gravy scores (< or = -0.515) tend to be soluble whereas higher gravy scores (> or = -0.512) form aggregates. Neither the GC content of the gene nor the relative percentage proline content of the protein affected the expression of the IPNS isozymes in E. coli.

Acremonium↗
PubMed1994

[Contamination of archives by filamentous fungi and their evaluation for potential pathogenicity].

The results of microbiological examinations of dust samples collected from mortgage registers in the court archives are presented. In the samples examined filamentous fungi of Penicillium genus were observed as well as Cladosporium herbarum, Geotrichum candidum, Cephalosporium glutineum, Mucor racemosus, Trichoderma viride and Aspergillus niger. Filamentous fungi of Penicillium genus occurred in the highest concentration accounting for 350,000 CFU/g. The levels of the remaining fungi were lower--they ranged from 500 CFU/g to 100,000 CFU/g. The concentration of filamentous fungi observed in archives can create health risk for workers.

Air Pollutants, Occupational↗
PubMed1975

Microbiological aspects of wood chip storage in tropical environments.

The microbiology of tropical wood chip storage has been examined in small experimental piles at two sites in New Guinea. Biodeterioration occurred in the forms of wood discoloration and loss of wood substance, including cellulosics; over a period of 2-4 months c. 20% per month of the chip pile by volume was seriously discoloured by microorganisms, and wood substance loss amounted to c. 1.5% per month (microscopic assessment). A range of microorganisms which produce discoloration were isolated. Decay was mainly due to soft-rotting microfungi such as Chaetomium globosum, C. thermophile, Humicola lanuginosa, Cephalosporium acremonium and Gliomastix subiculosa. Wood-rotting basidiomycetes were infrequent, although pockets of decayed (white rot) mycelial-matted chips were observed in the outer 1.5 m during dismantling of the 4-month-old pile at Vanimo. A successional trend of colonizing microorganisms was established, and profiles of the main zones of microbiological activity have been determined. The rapid rise in temperature, which is characteristic of wood chip piles after construction, had a marked influence on the microbial populations. Thermotolerant isolates included Humicola spp., Aspergillus spp., some actinomycetes, and members of the bacterial genus Bacillus. Reasonable chemical control of biodeterioration was achieved by dipping chip samples in a 1% solution of sodium pentachlorophenate. Three trichlorophenol formulations were less effective.

Alkaline Phosphatase↗
PubMedDate not supplied

[Cutaneous hypersensitivity in patients with bronchial asthma in La Comarca Lagunera].

A cross-sectional study was done to determine the frequency of cutaneous sensibility to aeroallergens and variations related to residence area. In a period of time from June 1994 to June 1995, we analyzed 101 patients residents in the Comarca Lagunera diagnosed as having allergic bronchial asthma. The patients were highly sensitive to pollen grains: Cynodon Dactylon (70%), Chenopodium (69%), Rusian Thistle (63%), Rye Grass (61%), Zea Maiz and Prosopis (57%). The sensitivity to molds was less: Candida (22%), Helmintosporium (18%) and Cephalosporium (16%). House Dust was positive in 55% and Dermatophagoides in 35%. Cotton hypersensitivity was poor (7%). There were not differences in cutaneous reactivity related with residence area.

Adolescent↗