[Unfolding of viscumin A-subunit during the intracellular transport of toxin].
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Biomedical subjects
Publications and source records attributed to E F Kolesanova.
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As it has been shown previously the site 311-318 of bacterial cytochrome P450cam (CYP101) contains an immunodominant continuous B-epitope. In order to investigate the role of single amino acid residues in antibody binding antigenic hexapeptide 312LKKGDQ317 analogues including single amino acid replacements were synthesized using Multipin technology. Antibodies from three anti-P450cam polyclonal rabbit sera interacted similarly to these peptides. The residue G315 was found to play a significant role in antibody recognition; any replacement leads there to considerable decrease of antibody binding. Residues L312, K313 and D316 occurred to be partly replaceable, whereas K314 and Q317 were not essential in recognition. These results correspond to known spatial structure of P450cam molecule. In its 312-317 site the polypeptide chain makes a turn and so some water-accessible atoms form a compact surface cluster including side chain atoms of K313 and D316, O-atom of K314 and C alpha-atom of G315, which present reliable Ig binding site. Side chain of K314 outlying from this cluster does not participate in the interaction. The received data permit to consider that the continuous epitope 312-317 of P450cam is conformationally dependent.
A study was made of the humoral immune response of BALB/c mice to various doses of artificial proteins that contained biologically active fragments of human interferon alpha 2 (IFN-alpha 2) and insulin. The insulin fragment had no effect on the response to any protein construct. The IFN-alpha 2 fragment increased the titer of antibodies against the construct. Mapping of continuous B epitopes with immune sera revealed several antigenic determinants, the C end of the IFN-alpha 2 fragment with the adjacent de novo protein region being immunodominant. More effective binding of serum antibodies with the constructs containing the IFN-alpha 2 fragment was attributed to antibody interaction with the fragment and to a better recognition of the entire protein construct by the immune system.
To analyze the interrelationships between the amino acid sequences of the proteins of hepatitis C virus and the functional characteristics of different variants of this virus, a database of protein functional mapping of hepatitis C virus was developed. The database contains amino acid sequences (both full-size and fragmentary) retrieved from accessible databases and experimental data published in literature. The database also contains the results of comparison and treatment of primary data, including alignments and functional regions. On the basis of these data, variable and conservative regions of envelope proteins of hepatitis C virus were revealed. Antigenic and functional maps of structural and nonstructural proteins of the virus were constructed. The most variable region of the envelope protein E2 (HVR1) was analysed. It is assumed that the conservatism of some amino acid positions of HVR1 is related to the functions of this region.
The immunogenicity of the artificial protein albebetin and its derivatives with active peptide fragments was investigated. We also studied the influence of the peptides on the immunogenicity of the whole construct and contribution of each component to the immunogenicity. Two of three studied proteins contained active peptides from human IFN-alpha and insulin. Three continuous antigenic sites with different immunogenic potential were recognized in the chimerical proteins. The interferon fragment was the immunodominant site in the albeferon and albeferon-insulin molecules, while the insulin fragment displayed low immunogenic activity. All continuous B-epitopes are located at the boundaries of the secondary structure elements and at the predicted surface-located sites of albebetin molecule. Thus, peptide fragments attached to the artificial protein carrier can influence immunogenicity of the resulting construct.
With the modern molecular biology techniques, it has been possible to detect, isolate and clone biological macromolecules, which could be used as immunogenes in artificial vaccine constructs. In the post-genomic era, the prospective immunogenic components are searched using bionformatic tools and proteomic technologies. Today it is quite realistic to combine the artificial vaccine constructs from the preselected molecular components. Existing computational methods are able to detect the potential immunogenes in genomic sequences, predict their characteristics and subcellular location. The set of methods is designed to predict the T- and B-epitopes that can be used as components of minimal vaccine constructs. The variety of systems for production and delivery of vaccines are developed and tested. These include transgenic plants, bacterial and viral vectors, DNA molecules etc. Several informational resources provide free access to molecular immunology data and deliver services on prediction of antigenic features. Several artificial vaccines have already been launched, but much more preparations are under preclinical and clinical trials. Computer-aided design of vaccines may significantly decrease time and costs required for their development. Modern bioinformatic technologies are now employed for discovery of more effective and potent vaccine.
Because of the high conservativity of cytochrome b5 cytosolic domain (t-cytochrome b5) among mammalian species the antibodies against bovine t-cytochrome b5 were successfully obtained only from evolutionary distant species (chicken). Antigenic mapping of t-cytochrome b5 by the peptide scanning method showed the presence of a large set of linear B-epitopes of this protein. This is well consistent with high content of water-accessible amino acid residues and polypeptide chain turns in its molecule. Linear B-epitopes of t-cytochrome b5 are presumably located in sites with species specificity of the amino acid sequence, despite of the high-degree surface exposure of the highly conservative site, which is probably responsible for the interaction with cytochrome P450. It can be explained by the absence of the effective T-helper support of the antibody response to amino acid sequence sites that are identical to own proteins of an organism. Nevertheless, antibodies against bovine t-cytochrome b5 possess high cross-reactivity with regard to rabbit full-sized cytochrome b5 because of the presence of one identical linear B-epitope and cross-interactions between other antigenic sites with minor structural differences.
Content of Met-enkephalin in rat adrenal glands and blood plasma as well as activity of the enzymatic systems catalyzing the enkephalins catabolism in blood serum were studied after a single administration of ethanol into rats. Dynamics of Met-enkephalin alterations studied suggest that phases of activation and inhibition occur in the secretion of the peptide from adrenal gland into circulation.