Interaction of chondroitin sulfate with enzymes

Chondroitin sulphate forms noncovalent electrostatic biocatalyst-glycosaminoglycan complexes in the solutions of enzymes. Chondroitin sulphate also interacts with enzymes developing complexes after carbodiimide activation of its carboxylic groups. Relatively low-molecular weight of biocatalysts (chymotrypsin, superoxide dismutase) forms stable noncovalent conjugates with the additional interaction as compared with electrostatic complexes. High-molecular weight of enzymes (acid phosphatase) develops covalent conjugates. Chondroitin sulphate is proposed for covalent binding of large proteins and multi-enzymatic complexes to obtain their stabilized derivatives for medical application.     

Properties of thermostable HtpR-mutant of Escherichia coli

A thermoresistant htpR mutant having a decreased level of proteolytic activity has been selected in E. coli strain K802 after the directed mutagenesis in vivo. The mutation results in the bacteriophage T7 RNA-polymerase stability, aminoglycosidephosphotransferase stability as well as in the decrease in the rate of proteolytic degradation of cytoplasmic proteins during the heat shock. The obtained mutant strain can, probably be used as a host for alien polypeptides production.     

Recombinations during DNA cloning

RecA-independent recombinations accompanying the processes of plasmids preparation and cloning into Escherichia coli cells are induced within the short direct and inverted repeats of several types.     

Synaptic connections between primary afferents and motoneurons in the spinal cord of anuran larvae

The relationship between dorsal root afferents and lumbar motoneurons has been studied in the isolated spinal cord of Rana ridibunda tadpoles. It was found that primary afferents do not form direct contacts with "primary" motoneurons innervating the axial musculature used by the larvae in swimming. Monosynaptic connections were revealed only between afferent fibres and lateral motor column motoneurons which innervate the developing hindlimb. The transmission in these synapses was dual: electrical and chemical. During the metamorphic stages when the locomotion is gradually taken over by the developing hindlimbs, an increase of the percentage of motoneurons receiving direct synaptic input from the primary afferents was observed.     

Sensitivity to cephalosporin antibiotics of infectious causative agents in surgery

Comparison of antimicrobial effects of cephalosporins of the 1st and 2nd generations showed that the latter were advantageous with respect to gram-negative bacteria causing surgical infections. Three cephalosporins of the 3rd generation were characterized by the highest activity against such bacteria, including Enterobacter spp. and indole positive strains of Proteus spp., as well as non-enzymatic bacteria. The antimicrobial spectra and MICs of the new cephalosporins with respect to the cultures isolated from surgical patients were different which requires in vitro sensitivity assay of each antibiotic.     

The protoplasts of Acremonium chrysogenum. Biochemical and morphological studies

A procedure for preparing stable A. chrysogenum protoplasts capable of 60 per cent regeneration was developed. Two morphogenetic types of the regeneration were detected. The variants isolated after the protoplast regeneration were characterized by wide ranges of morphological variation. Capacity for the antibiotic production varied from 60 to 160 per cent of the activity of the starting strain. A procedure for isolating functionally active mitochondria from protoplasts of A. chrysogenum was also developed. Their main bioenergetic parameters were studied. In the respiratory chain of the A. chrysogenum mitochondria there were detected three conjugation sites of oxidative phosphorylation.     

Composition and structure of the antibiotic polypeptide 308-I from Actinomadura recticatena

Antibiotic 308-I isolated from Actinomadura recticatena and the products of its degradation were studied with the methods of electron impact mass spectrometry, chemical ionization with ammonia, field desorption and ion extraction from solution under atmospheric pressure. It was shown that by its composition and structure antibiotic 308-I was identical to antibiotic BBM-928 A.     

Hybridization of A-factor deficient mutants of Streptomyces griseus by means of fusion of protoplasts

Characteristics of 6 A-factor deficient mutants of S. griseus are presented. The common feature of the mutants was impairment of sporulation, formation of aerial mycelium and streptomycin synthesis. Pair-by-pair hybridization of the mutants was performed with protoplast fusion followed by regeneration. 9 pair couplings of the mutants were performed. In 3 of them sporulating recombinants were detected. The antibiotic production level in 70 hybrids was different and ranged from 0 to 1700 micrograms/ml. The morphological features of the colonies and the number of the spores formed were also different. The common feature of all the 70 sporulating hybrid strains was recovery of synthesis of A-factor, an endogenic regulator of S. griseus development. Therefore, in the A-factor deficient mutants impairment of A-factor synthesis was induced not by the plasmid elimination, as was suggested, but by mutation of separate genes.     

Comparison of the action of pristan and Freund's incomplete adjuvant on the development of ascites in mice--the recipients of hybridoma cells

Production of immunodiagnostic preparations based on monoclonal antibodies requires large amounts of such antibodies. Most frequently preparative quantities of monoclonal antibodies are provided by ascitic fluid from hybridoma-carrying mice. Prior to intraperitoneal administration of hybridoma cells mice are subjected to stimulation with pristan, a mineral oil component. The authors showed that the Freund's incomplete adjuvant (FIA) may be as well used for this purpose. The effect of pristan and the FIA on ascites development in mice with hybridomas producing monoclonal antibodies to the Ia-like antigens of man was studied. The stimulants were administered in amounts of 0.5 ml per a mouse. It was shown that irrespective of the stimulant injection time and the number of the administered hybridoma cells the amount of the ascitic fluid formed in female mice BALB/c stimulated with the FIA was 1.5-3 times higher as that in the animals stimulated with Pristane, the antibody titer in the ascitic fluid being unchanged.     

Use of a protoplasting method for altering the qualitative and quantitative composition of the anthracycline complex in Streptomyces peucetius var. caesius

Conditions for efficient regeneration in mutant strains of the doxorubicin-producing organism Str. peucetius var. caesius were developed. The effect of the protoplast regeneration on changes in the proportion of the components of the anthracycline complex produced by these strains was shown. Variants with doxorubicin productivity 2 times higher than that of the parent strain were isolated.