Characteristics and identification of bacteriocins produced by Lactococcus lactis subsp. lactis 194-K

The Lactococcus lactis subsp. lactis 194-K strain has been established to be able to produce two bacteriocins, one of which was identified as the known lantibiotic nisin A, and the other 194-D bacteriocin represents a polypeptide with a 2589-Da molecular mass and comprises 20 amino acid residues. Both bacteriocins were produced in varying proportions in all of the studied culture media, which support the growth of the producer. Depending on the cultivation medium, the nisin A content was 380- to 1123-fold lower in the 194-K stain culture broth than that of the 194-D peptide. In comparision to nisin A Bacteriocin 194-D possessed a wide range of antibacterial activity and suppressed the growth of both Gram-positive and Gram-negative bacteria. An optimal medium for 194-D bacteriocin synthesis was shown to be a fermentation medium which contained yeast extract, casein hydrolysate, and potassium phosphate. The biosynthesis of bacteriocin 194-D by the 194-K strain in these media occurred parallel to producer growth, and its maximal accumulation in the culture broth was observed at14–20 h of the strain’s growth.     

Generation of recombinant antibodies and means for increasing their affinity

Highly specific interaction with foreign molecules is a unique feature of antibodies. Since 1975, when Keller and Milstein proposed the method of hybridoma technology and prepared mouse monoclonal antibodies, many antibodies specific to various antigens have been obtained. Recent development of methods for preparation of recombinant DNA libraries and in silico bioinformatics approaches for protein structure analysis makes possible antibody preparation using gene engineering approaches. The development of gene engineering methods allowed creating recombinant antibodies and improving characteristics of existing antibodies; this significantly extends the applicability of antibodies. By modifying biochemical and immunochemical properties of antibodies by changing their amino acid sequences it is possible to create antibodies with properties optimal for certain tasks. For example, application of recombinant technologies resulted in antibody preparation of high affinity significantly exceeding the initial affinity of natural antibodies. In this review we summarize information about the structure, modes of preparation, and application of recombinant antibodies and their fragments and also consider the main approaches used to increase antibody affinity.     

Activity-Dependent Actin Remodeling at the Base of Dendritic Spines Promotes Microtubule Entry

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Quantitative amino acid makeup and the characteristics of the amino groups of ristomycin and the products of its partial acid hydrolysis]

The quantitative amino acid composition of ristomycin A, a glycopeptide antibiotic, peptides I-IV (from partial acid hydrolysis of the antibiotic) and their dinitrophenylic derivatives was determined. It was shown that both ristomycin and free peptides I-IV contained one residue of ristomycinic acid and one residue of actinoidinic acid, diamino-dicarbonic amino acids of the glycylphenolic type. Peptides I-IV had close molecular weights, i.e. 1100-1200 and differed from each other in the gradually increasing numbers of NH2- and COON- groups, from one in peptide I to four in peptide IV. The quantitative amino acid analysis of the dinitrophenylic derivatives of ristomycin and peptides I-IV showed that the free NH2-group in peptide I belonged to ristomycinic acid, the same as in the antibiotic, while in peptides III-IV at least one of the free NH2-groups belonged to ristomycinic acid and the other belonged to actinoidinic acid.     

An antibiotic complex produced byStreptomyces werraensis 1365T

An antibiotic complex comprising four components (A, B, C, and X) was extracted from a native solution and myceliumof Streptomyces werraensis 1365T. The components were purified by column and thinlayer (TLC) Chromatographic procedures to study their physicochemical and biological properties. The results were used to identify the substances isolated. The preliminary data allowed us to identify the components X, A, and B as the previously described compounds undecylprodigiosin, anisomycin, and copiamycin, respectively, whereas component C is a natural compound which has probably never been described.     

Dynamic instabilities in microtubule cytoskeleton. A phase diagram

Instabilities in the growth and depolymerization of microtubules are considered in the framework of self-organization theory. An extended reaction-diffusion model for the microtubule dynamics has been formulated. A phase diagram of microtubule cytoskeleton has been constructed, which determines the regions of stability for steady and nonstationary solutions of the model. It is shown that the instabilities in microtubule dynamics result from kinetic nonequilibrium phase transitions. On the basis of phase diagram structure, a general classification of the microtubule cytostatic regulatory factors is suggested. The problem of mutual amplification of the activity of cytostatic agents is discussed.