bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effektor‐ und Precursorfunktion von Mannose‐6‐phosphat, Mannose‐l‐phosphat, UDP‐N‐acetylglucosamin und Dolichylphosphat bei der mikrosomalen Biosynthese von Proteophosphomannan der SCP‐Hefe Candida maltosa H
Authors: Röber B. , Reuter G. 
Published: February 2007

AbstractMicrosomal preparations from protoplasts of the yeast Candida maltosa, which is able to assimilate n‐alkanes, were used as enzyme source to catalyse the nicorporation of radioactivity from guanosine diphosphate 14C‐mannose, 3H‐mannose‐6‐phosphate, 3H‐mannose‐1‐phosphate or uridine diphosphate N‐acetyl‐(14C‐glucose)‐glusosamine in a mannose polysaccharide. The reaction product was identified as yeast mannan by comparing the saccharides prepared by alkaline degradation and by acetolysis, with those from in vivo proteophosphomannan, obtained in structural investigations.The enzyme preparation catalysed the formation of an almost unsubstituted α(1,6)‐linked mannan backbone from GDP‐Man. Man‐6P, dolichylphosphate and on the other hand UDP‐GNAc in the presence of ATP and dolichylphosphate are potent activators of the mannosyl transfer: α(1,3)‐(and α(1,3)‐) mannosyl transferases are activated by Man‐6P. Beside this Man‐6P is found to be a precursor for the incorporation of the first mannosyl (‐phosphate) unit in the side chain of a branched mannan and of the alkali‐labile bound oligosaccharides.The data presented support the hypothesis that Man‐6P, not activated by GTP, is a second mannosyldonator in the biosynthesis of proteophosphomannan.
Studies on sugar isomerases of Lactobacillus sp.
Authors: Shukla G. L. , Prabhu K. A. 
Published: February 2007

AbstractA culture of Lactobacillus sp. isolated from soil was found to contain glucose, xylose and ribose isomerase enzymes. Some of the factors affecting isomerase enzyme activities were studied with a view to isolate and purify the enzymes. Arsenate was not required in the enzyme reactions. At 10 mM concentrations sodium arsenate showed 65–70% inhibition of D‐glucose isomerase but did not affect D‐xylose and D‐ribose isomerases. At 5 mM concentrations EDTA showed 85–90% inhibition of D‐glucose and D‐ribose isomerases but not D‐xylose isomerase. Ca2+ ions showed inhibition of D‐glucose isomerase at a concentration of 1–2 mM, but inhibition could be reversed by increasing Mg2+ concentration in the enzyme reaction mixture. D‐Glucose enzyme production was maximal after 72 hrs of fermentation in shake flasks with Yamanaka medium containing glucose and xylose, and glucose isomerase activity in the culture increased up to 5–6 generations.Heat treatment of ultrasonic crude extract and of whole bacterial cells in the presence of Co2+/Mg2+ ions gave insoluble fixed active D‐glucose isomerase enzyme devoid of D‐xylose and D‐ribose isomerase activities. About 40 units (μM/min) of D‐glucose isomerase activity per gram of dry cells were obtained in whole cell immobilization.
Inducible nature of the steroid 11‐hydroxylases in spores of Cunninghamella elegans (Lendner)
Authors: Jaworski A. , Sedlaczek L. , Dlugoński J. , Zajaczkowska Ewa 
Published: February 2007

AbstractSpores harvested from steroid‐free media (non‐induced during sporogenesis), and used for cortexolone hydroxylation in the presence of cycloheximide to prevent enzyme synthesis during transformation produced cortexolone derivatives at a low rate: 4.85 ± 2.37 mg products per g dry weight per 6 hours.Spores induced during sporogenesis and transformation formed the hydroxylation products at the rate 40.25 ± 6.25 mg/g d.wt./6 h, whereas spores induced only once — on the stage of sporogenesis or during transformation — produced them at the rate 15.28 ± 4.80 – 18.85 ± 4.48 mg/g·6 h.The effectiveness of the hydroxylase induction during steroid transformation could be increased if spores pretreated with diluted KOH were used. This agent was shown to loosen the rigid structure of the spore envelopes, and to increase their permeability for the enzyme inducer. The similar could be shown with spores preincubated in a growth medium for 1–3 hours. Transformation rates of 51.34 mg/g·6 h and 68.82 mg/g·6 h were attained.
Gene expression at each stage of the life cycle of spore‐forming bacteria: Different sensitivity of transcription to antibiotics which act on DNA gyrase
Authors: Matsuda M. , Kameyama T. 
Published: February 2007

AbstractEffects of antibiotics acting on DNA gyrase, novobiocin and nalidixic acid on RNA synthesis during germination, vegetative growth and sporulation of Bacillus subtilis were examined.These drugs were relatively ineffective in inhibiting RNA synthesis of phase Gm 1 (5–15 min) during germination but effective in those of Gm 2 (15–40 min) and Gm 3 (40–60 min) during germination (Matsttda and Kameyama 1980).No distinguishable inhibitory effects of RNA synthesis in B. subtilis Novritt mutant could be detected by novobiocin. Bna synthesis of Gm 2 and Gm 3 of this mutant was inhibited by nalidixic acid.When novobiocin was added to exponential vegetative cell or sporulating cell culture at T0 and T1 stage, the rate of Bna synthesis was inhibited by 80% for 5 min following addition of the drug. However, Bna synthesis after T2 of sporulation became resistant toward novobiocin, as was the case at an early stage of germination.RNA profiles from transcripts synthesized on administration of Nov suggested that the suppression of the synthesis of 23S and 16S rRNA is relatively greater than 4 to 5S RNA at the middle stage of germination and at vegetative growth stage in the presence of NOV.Our present data suggest that DNA gyrase is involved in the regulation of gene transcription during middle and late phases of germination, vegetative growth and T0 and T1 of sporulation. The transcription during early phase of germination and sporulation after T2 may proceed independently of this enzyme.
Microbial side‐chain degradation of sterols
Authors: Kieslich K. 
Published: February 2007

AbstractApart from the broadly used diosgenin and some further natural compounds sterols gained an increasing importance as raw material for the synthesis of steroid drugs.Parallel to the elucidation of the pathways of the enzymatic degradation of sterols technical processes were developed for a specific degradation of the side‐chain to useful primary products. A review is given on the present state of this field and the trends to further improvements.
Biochemical and genetic studies of a histidine regulatory mutant of Streptomyces coelicolor A3 (2)
Authors: Derkos‐Sojak Vlasta , Pigac Jasenka , Delić V. 
Published: February 2007

AbstractThe specific activities of three enzymes in a histidine regulatory mutant RF59 of Streptomyces coelicolor A3(2) resistant to the histidine analogue 1,2,4‐triazolealanine (TRA) were measured and compared to the activity of the wild type strain. The first enzyme of the histidine pathway, phosphorybosyl‐ATP‐pyrophosphorylase (PR‐ATP‐pyrophosphorylase), of mutant RF59 and the wild type was sensitive to allosteric inhibition by L‐histidine and hence feed‐back inhibition was not affected by mutation, although the specific activity in the mutant was 2.9 fold higher than in the wild type.The other two enzymes coded by genes from the histidine operon were significantly derepressed. The enzyme D‐erythroimidazoleglycerol phosphate dehydrase (IGP‐dehydrase) in mutant RF59 had a 4.9 fold higher specific activity than in the wild type strain. The specific activity of the last enzyme of the pathway, histidinol‐dehydrogenase (Hol‐dehydrogenase), in the mutant was 4.7 fold derepressed compared to the wild type strain.The results of genetic crosses revealed the mapping of RF59 regulatory mutation between argA1 and cysD18 on S. coelicolor chromosome, suggesting that the mutant RF59 is a regulatory mutant unable to fully repress genes of the histidine pathway.
Occurrence of squalene and dehydrosqualene in streptomycetes
Authors: Gräfe U. , Reinhardt G. , Hänel F. , Schade W. , Gumpert J. 
Published: February 2007

AbstractSqualene, dehydrosqualene and related hydrocarbons were found to constitute an essential part of the neutral lipid fraction extracted from mycelia and membranes of S. hygroscopicus, S. griseus and S. noursei. In comparison with the fraction of the triglycerides, these terpenoid compounds failed to incorporate (U‐14C)‐acetic acid throughout pulse labelling experiments. This suggested that the pertinent precursors were formed via alternative routes, for instance by catabolising branched‐chain amino acids.
Nature and significance of microbial cometabolism of xenobiotics
Authors: Janke D. , Fritsche W. 
Published: February 2007

AbstractMicrobial cometabolism, i.e. “transformation of a non‐growth substrate in the obligate presence of a growth substrate or another transformable compound” (Dalton and Stirling 1982) is a whole‐cell phenomenon physiologically based on coupling of different catabolic pathways at the cellular level. It is frequently observed in transformation of xenobiotic non‐growth substrates by individual microbial species. Transformation processes of this type are usually mediated by appropriate nonspecific enzymes of the peripheric cellular metabolism able to modify a variety of substances other than their natural substrates.The precise mechanisms of coupling between metabolism of xenobiotic non‐growth substrates and of particular additional carbon substrates may be different depending on the substrates and the microbial species involved. However, experimental data indicate that the primary function of the respective additional carbon substrates is to supply either energy, cofactors or metabolites for the different cellular events involved in the transformation process (e.g. uptake of the xenobiotic non‐growth substrate, functioning of appropriate degradative enzymes of the peripheric cellular metabolism).Cometabolism of xenobiotics involves nothing special or novel from the standpoint of biochemistry. On the contrary, there are numerous examples where the turnover of particular natural compounds by certain aerobic or anaerobic microorganisms is essentially based on coupling of different catabolic pathways at the cellular level by transfer of hydrogen (i.e. reducing power) and/or energy between two or more enzymatic reactions. Synthetic chemicals which resist total degradation by individual microbial species may undergo mineralization due to complementary catabolic sequences mediated by certain multispecies microbial associations with cometabolic transformations being the initial steps.Although taking place in certain natural habitats (e.g. rhizospheres, sewage), microbial cometabolism of xenobiotics in natural ecosystems occurs with slow rates since the respective cometabolizing populations are generally small and will not increase in number or biomass in response to the introduced chemicals. However, under conditions of axenic microbial cultures, high concentrations of biomass, and appropriate substrate mixtures cometabolism of synthetic chemicals may be a useful technique of considerable practical importance to accumulate biochemical products at high yields. In addition, cometabolic capabilities of wild‐type microorganisms may serve as a tool for the construction of microbial strains with a new degradative potential for recalcitrant xenobiotic compounds.
Biotest zum Nachweis von Hydroxamat‐Fe‐Chelatoren (Aerobactin)
Authors: Rabsch W. , Reissbrodt R. 
Published: February 2007

AbstractDifferent Salmonella strains were tested for aerobactin production in a hydroxamate‐bioassay with the aerobactin indicator strain E. coli LG 1522. The majority of hospital strains of Salmonella typhimurium produce hydroxamate siderophore. On the other hand S. typhimurium strains belonging to phage type n. c. 1/72/n. c., biochemical type b from human and animal sources, were unable to produce this siderophore. Serotypes other than S. typhimurium for example the multi‐resistent S. wien hospital strains, which were isolated in western europe and in the GDR, can excreate hydroxamate siderophore. Plasmids pIE 528 and pIE 5 234 isolated from Salmonella hospital strains produce hydroxamate siderophore in the enterobactin negative Salmonella typhimurium‐strain enb‐7.Thus, the hydroxamate bioassay may be a useful supplementary test for epidemiological strain characterization.
Parasexual process in the yeast Yarrowia lipolytica
Authors: Kurischko Cornelia 
Published: February 2007

AbstractGenetic studies of several events of the life cycle of Y. lipolytica demonstrated that diploid strains were unstable and produced mitotic segregants by haploidization. A screening system was developed which enabled us to show that parasexual processes can take place in addition to the sexual life cycle. This haploidization occurred through aneuploid intermediates as was proven statistically by the deviations from the segregation pattern as well as by the segregation data of the clones.The direction of the cross, was — with respect to the resistance to 2‐deoxyglucose of A‐ or B‐strain — not important for selection of mitotic segregants.
Surface hydrophobicity of plasmid‐carrying virulent Shigella flexneri and their avirulent variants
Authors: Seltmann G. , Tschäpe H. , Pál T. 
Published: February 2007

AbstractFive pairs of strains of S. flexneri each differing in the colour of their colonies after growth on Congo red agar have been tested for their ability to cause keratoconjunctivitis in the guinea pig eye, for the presence of the 140 Md virulence plasmid, for the presence of the virulence marker antigen, and for their ability to adsorb to hydrophobic surfaces (cellulose nitrate filters and Phenyl Sepharose). The results suggest that the presence of the 140 Md virulence plasmid provides the bacterial surface with a rather high degree of hydrophobicity; exceptions have been found.
Effect of temperature on growth and protein turnover in Bacillus megaterium
Authors: Strnadová M. , Prasad R. , Kučerová H. , Chaloupka J. 
Published: February 2007

AbstractThe Arrhenius plot of the specific growth rate μ of an asporogenic mutant of Bacillus megaterium, growing in the range of 17–37 °C followed a straight line, whose slope was affected by the composition of the medium. The maximal μ was found at 40° C in all media tested and decreased rapidly above 42° C. The portion of protein degraded also followed a straight line but reached its maximal value at 45–47° C. Its slope was affected substantially by the composition of the medium; the mixture of amino acids suppressed protein degradation at temperature lower than 37° C. The extent of the short‐lived protein fraction, degraded with the half‐time of about 1 h, was mostly affected by both — the temperature and the medium. The amount of proteins degraded per one biomass doubling was almost constant up to 37° C but was affected by the composition of the medium. At higher temperatures it increased rapidly and reached values of 20–40% of pulselabelled proteins degraded per one cell cycle. The degradation of ethionine‐containing proteins was similarly dependent on the temperature but the extent of proteins degraded was increased.
The fungal flora of post‐harvest grains of Sorghum guineense Stapf and their importance in pathogenicity
Authors: Ogundero V. W. 
Published: February 2007

AbstractThe mycoflora of air‐dried grains of Sorghum guineense and their importance in pathogenicity were studied. Nine species of both phytopathogens and saprophytic storage fungi were consistently obtained. The pathogenic fungi included Cladosporium vignae Gardner, Macrophomina phaseolina (Tassi) Goid and Helminthosporium turcicum Pass., While the saprophytes were mostly species of Aspergillus particularly A. flavus Link, A. fumigatus Fres. and A. niger van Thieghen. Pathogenicity tests showed C. vignae, M. phaseolina and H. turcicum to be seed‐borne pathogens of Sorghum guineense and gave symptoms ranging from leafblight to brown spot diseases of the leaves. The ability of the pathogens to produce cell wall‐degrading enzymes in vitro was studied while the fungi were shown to grow well at a wide temperature range of 20°–30 °C.
Saprophytic fungi and the deterioration of malting grains of Sorghum guineense Stapf
Authors: Ogundero V. W. 
Published: February 2007

AbstractThe ability of Humicola insolens Cooney & Emerson and Aspergillus fumigatus Fres. to cause biochemical changes in the components of milled Sorghum guineense grains and the factors necessary for these activities were studied. Significant losses (at p = <0.01) in the cellulose, hemicellulose, diastase and ethanol soluble fractions of the malted grains were recorded on inoculation with asexual spores of A. fumigatus and H. insolens and 21 days of incubation at 35 °C and 45 °C, respectively. This was accompanied by a corresponding rise in the total nitrogen components of the medium with period of incubation. None of the microbes was able to degrade the lignin components of the malted grains. While A. fumigatus was most active on the grains at 35 °C and pH 6.2, H. insolens grew best at 45 °C and pH 5.4.When both fungi were grown on varying sources of carbon and nitrogen good results were obtained on most of them with optimal growth recorded on starch and dextrin and the organic nitrogen sources l‐asparagine, l‐glutamic acid and l‐alanine. Both fungi also produced extracelluearly amylase, cellulases, pectate lyase, xylanase, protease, lipase, DNase and RNase. The potential health risks which the presence of these fungi on malted Sorghum grains pose to the consumers of the end products are discussed.
Effect of methyl viologen and oxygen concentration on thermophilic bacteria
Authors: Allgood G. S. , Perry J. J. 
Published: February 2007

AbstractThe level of superoxide dismutase, catalase, and peroxidase was determined in obligately thermophilic bacteria after growth either in the presence of methyl viologen (paraquat) or exposed to an increased atmospheric oxygen concentration. In general, the superoxide dismutase lever in these organisms was not altered by paraquat addition and had a varied response to oxygenation. Incorporation of paraquat in the growth medium resulted in minimally three‐fold higher levels of catalase. The peroxidase level varied as a response to oxygen stress whereas cellular catalase levels were generally higher.
Zur Heptoseregion der Lipopolysaccharide von Pasteurella multocida
Authors: Erler W. , Feist H. , Jacob Brigitte , Schade W. 
Published: February 2007

AbstractThe heptose region of the lipopolysaccharides (LPS) of Pasteurella multocida consists of the trisaccharide l Hep 1 → 2 l Hep 1 → 3 L Hep or l Hep 1 → 3 l Hep 1 → 2 l Hep. This trisaccharide and the oligosaccharide consisting of 3 moles heptose and 1 mole glucose were isolated from the LPS of the strain D 33. The data suggest that the LPS biosynthesis of P. multocida is different from that of Salmonella spp.
Purification and some properties of threonine dehydratase from Candida maltosa
Authors: Bode R. , Schult I. , Birnbaum D. 
Published: February 2007

AbstractThreonine dehydratase has been purified about 200‐fold from extracts of Candida maltosa by chromatography on DEAE‐cellulose, Sephadex G‐200, and hydroxylapatite. The enzyme is fairly stable in solution in the presence of 250 mM phosphate buffer containing 40% glycerol. The molecular weight of the native enzyme was calculated to be approximately 190,000. The molecular weight of a subunit of the enzyme was estimated to be 46,000 by SDS gel electrophoresis. The enzyme seemed to have a tetrameric structure consisting of four identical subunits. The enzyme is subject to feedback inhibition by isoleucine and is stimulated by valine and phosphate ions. Kinetic studies indicate that there are more than one binding site for each effector on the enzyme. It is concluded from these investigations that the binding sites for threonine as well as for isoleucine are distinct from another, whereas the binding sites for valine and phosphate are identical or closely overlapping.
ARS‐Aktivität von Kinetoplasten‐DNA in Hefezellen
Authors: Gütter H.‐P. R. , Maslow D. A. , Kolesnikow A. A. , Börner Th. 
Published: February 2007

AbstractDifferent fragments of the maxicircle of the kinetoplast DNA (kpDNA) from Crithidia oncopelti were cloned (Fig. 1, 2) and tested for ARS‐activity (ARS, autonomously replicating sequences). ARS‐avitivity was expressed as number of transformed yeast cells per μg plasmid DNA, as number of transformed cells per number of plasmid molecules (transformation efficiency, TE) and as number of transformed cells per kilobasepair of cloned kpDNA (specific transformation efficiency, TE8) (Fig. 3. Table 1). All DNA fragments studied showed ARS‐activity. Large fragments exhibited higher ARS‐activities than their smaller subfragments. The number of fragments showing ARS activity and their distribution within the maxicircles (Fig. 4) suggest that there was no strong correlation between sites with ARS‐activity and the replication origin of kpDNA.
Interaction of anthracycline antibiotics with biopolymers: Comparative studies of DNA binding and antimicrobial activity of rhodomycin‐type anthracycline antibiotics
Authors: Stutter E. , Walter Axel , Fleck Werner F. 
Published: February 2007

AbstractThe binding of the anthracyclines β‐rhodomycin‐I and β‐rhodomycin‐II to calf thymus DNA was investigated by both equilibrium and kinetic methods taking into account ligand dimerization (ionic strengthI= 0.2 M, pH 6.0). The analysis was based upon a cooperative single‐step binding mechanism with overlapping of potential binding sites on a linear homogeneous lattice. Equilibrium binding parameters were estimated from spectrophotometric titration experiments by means of a nonlinear fitting program. The results were compared with those obtained previously for the related antibiotic iremycin and were complemented by kinetic parameters determined from temperature‐jump experiments at high binding ratio.The binding constants and the mean attachment times of the drugs were found to increase in the serial order iremycin, β‐rhodomycin‐I and β‐rhodomycin‐II, which is in line with their increasing antimicrobial activity onBacillus subtilisATCC 6633.
Tubular cytoskeletal elements in sporangia and zoospores of Phythophthora infestans (MONT.) DE BARY (Oomycetes, Pythiaceae)
Authors: Jelke E. , Oertel B. , Böhm K. J. , Unger E. 
Published: February 2007

AbstractSporangia and zoospores of the oomycete Phytophthora infestans are characterized by a number of tubular cytoskeletal elements: Single and bundled cytoplasmic microtubules, arising from electron dense material at the centrioles, form a network inside the zoospores of the fungus. Nucleus‐associated microtubules surround the nucleus in a basket‐like manner. Spindle microtubules occurring during mitosis in zoosporangia are partially maintained from the late telophase till the zoospore stage. The pattern of flagellar microtubules is identical to that of the typical eukaryotic flagella. The bundles of 15 nm‐tubules observed in ER‐cisternae of zoosporangia and zoospores are similar to preformed mastigonemes of tinsel flagella because of their dimensions. Microtubules, flagellar fragments, and mastigonemes, similar in substructure to those of other lower and higher eukaryotes, have been isolated from zoospores of Phytophthora infestans by lysis in Triton X‐100 on microtubule‐stabilizing conditions.