L. K. Shataeva

Short Cell-Penetrating· Peptides: A Model of Interactions with Gene Promoter Sites

Analysis of the main parameters of molecular mechanics (number of hydrogen bonds, hydrophobic and electrostatic interactions, DNA-peptide complex minimization energy) provided the data to validate the previously proposed qualitative models of peptide–DNA interactions and to evaluate their quantitative characteristics. Based on these estimations, a three-dimensional model of Lys-Glu and Ala-Glu-Asp-Gly peptide interactions with DNA sites (GCAG and ATTTC) located in the promoter zones of genes encoding CD5, IL-2, MMP2, and Tram1 signal molecules.

Epigenetic aspects of peptide-mediated regulation of aging

Endogenous peptides in the cyto- and nucleoplasm are formed upon the specific proteasomal degradation of nuclear proteins. These peptides are formed by short blocks of amino-acid residues with charged side groups and therefore a high local concentration of electrostatic charge of either sign is characteristic of them. These peptides are capable of complementary binding to certain short nucleotide sequences in DNA strands. This binding can cause a significant weakening of the interstrand bonds in the double helix of DNA and therefore stimulate the splitting of strands, which is necessary for gene transcription and replication. Aging is always accompanied by a decrease in the degree of genome methylation. The age-related decrease of the degree of methylation of nucleotide repeat sequences in the genome promotes the site-specific binding of short peptides to DNA, which hinders the hydrolysis of non-methylated DNA fragments by endonucleases. The available experimental data on the peculiarities of binding to methylated DNA are indicative of the involvement of short peptides in the epigenetic regulation of aging processes.

Extraction and activity of regulatory peptides from sea urchin eggs

Experiments were performed to extract low molecular weight peptides from the eggs of the sea urchin Strongylocentrotus pallidus using sterilizing microfiltration and solid-phase extraction, along with analytical gel chromatography and spectroscopy. The peptides extracted had molecular weights of 360 – 1200 Dal and were divided into two fractions: acidic peptides contained a predominance of glutamic and aspartic acid residues, along with aromatic amino acid residues; alkaline peptides contained mainly lysine and arginine residues and lacked aromatic amino acids. Assessment of the biological activity of these extracts demonstrated high specificity in stimulating the development of explants in organotypic cultures of spleen, testicle, myocardium, and cerebral cortex tissues.

A membrane bioreactor with immobilized proteinase

A procedure was developed for layer-by-layer immobilization of terrilytin proteolytic enzyme on track membranes and flat-membrane blocks. The hydrolysis of fibrinogen and casein was studied, and the possibility of using such a structure as an enzymatic bioreactor was demonstrated.

Isolation of Peptides from Calf Brain Tissue and Evaluation of their Tissue-Specific and Stimulatory Activity

A method for separating a mixture of calf brain peptides by extraction with aqueous HOAc followed by fractionation of the extract by cross-flow (tangential) microfiltration and solid-phase extraction was developed. The isolated peptide mixture contained constituents with molecular masses within 0.1 – 3 kDa. Low-pressure ion-exchange chromatography of this mixture over Dowex 50WX8 sulfonated cation exchanger isolated a pure peptide consisting of the five amino acids Arg, Lys, Gly, Ser, and Leu. The biological activity of the obtained pentapeptide was estimated on organotypic brain slice culture explants of Wistar rats. It was established that the peptide possessed high tissue-specific and stimulatory activity for brain explants that was greater than those of the commercial preparations Cortexin and Cerebrolysin.

Modification of Poly(Ethylene Terephthalate) Track Membranes by Sorption of Poly(Ethylene Glycol)

Sorption of poly(ethylene glycol) on poly(ethylene terephthalate) track membranes was studied at different pH. The hydrophilic-hydrophobic properties of the intact membranes and those modified with poly(ethylene glycol) are compared. The membrane-aqueous human serum albumin and membrane-aqueous insulin adhesive tensions were determined for modified membranes. The competitive sorption of human serum albumin and poly(ethylene glycol) from aqueous solution on the track membranes is analyzed.