The effect of low doses of echinochrome A (EchA), a natural polyhydroxy-1,4-naphthoquinone pigment from the sea urchin Scaphechinus mirabilis, has been studied in clinical trials, when it was used as an active substance of the drug Histochrome^® and biologically active supplement Thymarin. Several parameters of lipid metabolism, antioxidant status, and the state of the immune system were analyzed in patients with cardiovascular diseases (CVD), including contaminating atherosclerosis. It has been shown that EchA effectively normalizes lipid metabolism, recovers antioxidant status and reduces atherosclerotic inflammation, regardless of the method of these preparations’ administrations. Treatment of EchA has led to the stabilization of patients, improved function of the intracellular matrix and decreased epithelial dysfunction. The increased expression of surface human leukocyte antigen DR isotype (HLA-DR) receptors reflects the intensification of intercellular cooperation of immune cells, as well as an increase in the efficiency of processing and presentation of antigens, while the regulation of CD95 + expression levels suggests the stimulation of cell renewal processes. The immune system goes to a different level of functioning. Computer simulations suggest that EchA, with its aromatic structure of the naphthoquinone nucleus, may be a suitable ligand of the cytosolic aryl cell receptor, which affects the response of the immune system and causes the rapid expression of detoxification enzymes such as CYP and DT diaphorase, which play a protective role with CVD. Therefore, EchA possesses not only an antiradical effect and antioxidant activity, but is also a SOD3 mimetic, producing hydrogen peroxide and controlling the expression of cell enzymes through hypoxia-inducible factors (HIF), peroxisome proliferator-activated receptors (PPARs) and aryl hydrocarbon receptor (AhR).

The structure and functional properties of nonspecific porins (β-structured integral proteins of the outer membrane of Gram-negative bacteria) are overviewed. The characteristic features of porin spatial structure related to the principles of β-barrel construction and pore geometry are considered. The data concerning nonspecific diffusion of low-molecular substances and dynamic behavior of porin channels dependent on the distribution of charged amino acid residues in different structural domains of the porin molecule are presented. The methods and approaches used in the study of functional activity of porins are surveyed. The data on modulation of pore-forming activity of these proteins by external factors and membrane components are considered separately.

Irreversible denaturation of membrane proteins in detergent solutions is similar to unfolding of water-soluble multidomain proteins and represents a complex, multistage process. Pore-forming proteins of Gram-negative bacteria are heat-modifiable proteins, i.e., proteins altering their molecular forms (trimers or monomers), and accordingly, their electrophoretic mobilities depending upon denaturation conditions. There are still some contradictory data on the peculiarities of the conformational changes in the porin structure with temperature. Some authors demonstrated the loss of the porin trimeric structure only after unfolding of monomer subunits. Other researchers initially observed the dissociation of porin oligomers into the folded monomers. Using SDS-PAGE, spectroscopic methods and differential scanning calorimetry, a detailed study of thermally induced changes in the spatial structure of OmpF porin from the fish pathogen Yersinia ruckeri (Yr-OmpF) was carried out. The data obtained allowed us to conclude unambiguously that changes in the spatial structure of the monomers of Yr-OmpF precede the dissociation of the porin trimer.

Marinomonas primoryensis KMM 3633^T, extreme living marine bacterium was isolated from a sample of coastal sea ice in the Amursky Bay near Vladivostok, Russia. The goal of our investigation is to study outer membrane channels determining cell permeability. Porin from M. primoryensis KMM 3633^T (MpOmp) has been isolated and characterized. Amino acid analysis and whole genome sequencing were the sources of amino acid data of porin, identified as Porin_4 according to the conservative domain searching. The amino acid composition of MpOmp distinguished by high content of acidic amino acids and low content of sulfur-containing amino acids, but there are no tryptophan residues in its molecule. The native MpOmp existed as a trimer. The reconstitution of MpOmp into black lipid membranes demonstrated its ability to form ion channels whose conductivity depends on the electrolyte concentration. The spatial structure of MpOmp had features typical for the classical gram-negative porins. However, the oligomeric structure of isolated MpOmp was distinguished by very low stability: heat-modified monomer was already observed at 30 °C. The data obtained suggest the stabilizing role of lipids in the natural membrane of marine bacteria in the formation of the oligomeric structure of porin.