The structure of antibiotic eremomycin B

A new biologically active component, antibiotic eremomycin B, was isolated from the culture liquid of Amycolatopsis orientalis subsp. eremomycini, the producing strain for antibiotic eremomycin. Its structure was established by NMR spectroscopy and mass spectrometry. Eremomycin B was shown to differ from eremomycin by the presence of an N-carboxymethyl substituent in the disaccharide eremosamine fragment.     

Influence of regulatory genes of type 1 human immunodeficiency virus on proliferation and differentiation of murine embryonic stem cells

Spontaneous formation of embryoid bodies and subsequent differentiation of some cells into cardiomyocytes were demonstrated on murine embryonic stem cells of R1 line. The lines of embryonic stem cells were obtained that had been transfected with genetic constructs carrying expressing regulatory genes of the human immunodeficiency virus tat and nef and "green protein" gene (GFP). The transfection of embryonic stem cells with the gene tat stimulated their proliferative activity, while this activity decreased in the cells transfected with the gene nef. The time necessary for the formation of embryoid bodies by all lines of transfected cells was similar to that in the control cells. In the cultures of cells transfected with nef and tat, the number of embryoid bodies and the percentage of embryoid bodies with contracting cardiomyocytes were higher and lower than in the control, respectively. Thus, an inverse correlation was observed between the effects of regulatory genes of the human immunodeficiency virus on proliferation and differentiation embryonic stem cells.     

Echinomycin production by Actinomadura sp. INA 654]

An actinomycete strain designated as Actinomadura sp. INA 654 was isolated from a chernozem soil sample in the Voronezh Region by the soil sample treatment with millimetric waves (EHF band). The strain produced an antibiotic complex of 2 components, named A-654-I and A-654-II. Investigation of their physico-chemical properties showed that A-654-I was identical to echinomycin, a heteropeptide lactone of the quinoxaline group with antitumor activity, while A-654-II proved to be likely a new natural compound. Production of echinomycin by a representative of the Actinomadura genus was detected for the first time. Up to now, only representatives of the Streptomyces genus were known to produce echinomycin.     

Antibiotic properties of the strains of the basidiomycete Lentinus edodes (Berk.) sing]

Antibiotic properties of the extracts from the fermentation broth and mycelium of 15 strains of the edible and medicinal basidiomycete L. edodes were studied and it was shown that the extracts were active against grampositive and gramnegative bacteria, yeasts and mycelial fungi, including dermatophytes and phytopathogens. The strains differed by the set of the organisms susceptible to the action of the extracts. Strains of L. edodes combining marked antibiotic properties and high yields of water soluble polysaccharides were screened. The active compounds were detected by preparative TLC. Two of them were identified with UV- and mass spectrometry as lentinamycin B and erytadenine (lentinacin). Lentinamycin B was found to be the main component responsible for the antibiotic activity of the L. edodes strains.     

Antibodies to the nonnative forms of d-glyceraldehyde-3-phosphate dehydrogenase: identification, purification, and influence on the renaturation of the enzyme.

Monoclonal antibodies of two clones reacting with the nonnative forms of d-glyceraldehyde-3-phosphate dehydrogenase, EC 1.2.1.12 (GAPDH), were obtained. Antibodies of clone 6C5 belonged to IgG1 subtype; antibodies of clone 6G7 belonged to IgM type. The interaction of antibodies of both clones with the immobilized and soluble enzyme was studied. The specificity of antibodies to the definite oligomeric forms was demonstrated on immobilized monomers, dimers, and tetramers of GAPDH. The affinity of antibodies to monomeric and dimeric forms of GAPDH, either active or not, was demonstrated. At the same time the antibodies did not react with the tetrameric enzyme. The binding of antibodies had no influence on the enzymatic activity. However, the addition of antibodies to the denatured enzyme blocked the spontaneous renaturation of GAPDH. The immobilized antibodies of both clones were successfully used for the purification of GAPDH solution from the denatured admixtures.     

Development of a new method for preparing biologically active compounds based on the typed strain Streptomyces werraensis

The regulatory function of a DNA fragment responsible for actinomycin resistance in the typed strain Streptomyces werraensis ATCC 1365, which produces a macrotetrolide antibiotic, was studied. Metabolic changes made this strain capable of producing an antibiotic complex, which comprises four biologically active compounds absent from the parent culture.     

Dynamic instabilities in the microtubule cytoskeleton: A state diagram

The dynamics of microtubule growth and disassembly is considered in the framework of the theory of nonequilibrium reaction-diffusion systems. The phase diagram contains regions corresponding to stable stationary and nonstationary solutions. Dynamic instabilities can arise from nonequilibrium kinetic transitions. Agents affecting the microtubule dynamics are classed into four types, and the interplay of their effects is analyzed.     

Localization of antigenic sites for monoclonal antibodies against alpha-subunit of Go-protein from the bovine brain]

The properties of monoclonal antibodies (MA) specifically raised against the alpha-subunit of the GTP-binding protein from bovine brain, G0, were studied. The hybridoma clones were found to secrete MA capable to interact with different antigenic sites of G0 alpha. Clone 1D2 MA interacted with the N-terminal domain of G0 alpha. The antigenic sites for clones 3DE. 1H6 and 2E3 MA were localized in the C-terminal domain of the protein molecule. Using clone 1H6 MA, the site of G0 alpha involved in the interaction with the beta gamma complex located in the C-terminal domain of the alpha-subunit, was revealed. It was found that the interaction of the alpha-subunit with the beta gamma complex changed the conformation of the C-terminal fragment of G0 alpha (Mr5000) together with an increase in the alpha-subunit affinity for clone 2E3 MA. It was concluded that the observed conformational changes may be the reason for the increased affinity of the alpha-subunit for the receptor.     

Application of recombinant antibody fragments for troponin I measurements

The cardiac isoform of troponin I is a reliable biomarker of damaged cardiomyocytes that accompanies such severe cardiovascular diseases as myocardial infarction. Monoclonal antibody 19C7 recognizes troponin I in the blood-stream with high affinity and specificity. Recombinant antibodies can be used to improve detection systems based on monoclonal antibodies produced with hybridoma technology. In the present study, we compare the properties of monoclonal anti-body 19C7 and its recombinant fragments. It is shown that the recombinant antibody fragments demonstrate similar affinity values as monoclonal antibodies and can be applied for troponin I detection.