Redistribution of Ca2+ ions in lymphocyte suspensions after treatment with an ionophore

Ionophore A23187 induces three-phase kinetics of reduction of chlorotetracycline (CTC) lauded lymphocyte fluorescence: fast reduction, low increase and lower reduction of fluorescence. We suggested the following explanation of kinetics. The first phase is extinguishing of the Ca2+ - CTC complex fluorescence induced by ionophore A23187 perturbation of the cell membrane, the second one is the energy dependent Ca2+ entry into the cell and the third one is the slow efflux of Ca2+ ions from the cell to concentration gradient.     

Determination of the “Amino Acid Conflicts” and amino acid substitutions in primary structures of 41 human proteins by the proteomic technologies

Proteomic studies of some human tissues and organs (skeletal muscles, myometrium, motor zone of the brain, prostate), and also cultivated myoblasts revealed 41 proteins, in which the presence of certain variants of amino acids (“conflicts”) was recognized at several “conflict” positions. Among the 93 registered “amino acid conflicts”, seven cases represented the results of the protein polymorphisms caused by corresponding substitution of individual amino acid. Proteomic analysis of prostate proteins revealed two isoforms of a prostate-specific antigen, formed due to alternative splicing. Thus, our results have shown that employment of the proteomic technologies may characterize various types of biochemical polymorphism in many human proteins.     

A noncanonical binding site of chloramphenicol revealed via molecular dynamics simulations

Chloramphenicol, an antibiotic belonging to the family of amphenicols, is an inhibitor of translation. On the basis of X–ray structural analysis of the binding of chloramphenicol to free bacterial ribosomes, the chloramphenicol action mechanism that consists in preventing the binding of aminoacyl-tRNA to the A–site of the large subunit of the ribosome was adopted. However, the known structures of chloramphenicol complexes with bacterial ribosomes poorly explain the results of the experiments on the chemical modification of 23S rRNA, the resistance to chloramphenicol caused by mutations in 23S rRNA and, which is particularly important, the selectivity of chloramphenicol in suppression of translation, depending on the amino acid sequence of the nascent peptide. In the present study the putative structure of the chloramphenicol complex with a bacterial ribosome in the A,A/P,P–state has been obtained by molecular dynamics simulations methods. The proposed structure of the complex allows us to explain the results of biochemical studies of the interaction of chloramphenicol with the bacterial ribosome.     

Ribonuclease inhibitors

RNases are important enzymes of cell metabolism, influencing gene expression, affecting cell growth and differentiation, and participating in cell defense against pathogens and induction of apoptosis. Since RNases mostly occur in complex with their inhibitors in the cell, the inhibitors also play a role in the above processes. The review considers natural protein RNase inhibitors of animals, plants, and bacteria, as well as synthetic low-molecular-weight inhibitors. Special emphasis is placed on the prospective use of RNase inhibitors in the therapy of cancer and allergy. While RNases are widespread, the number of the available natural and synthetic inhibitors is limited. A pressing problem is to design highly effective low-molecular-weight inhibitors of the RNase activity of angiogenin and eosinophil-associated RNases for anticancer and antiallergy therapy.     

Effects of p-Nitrophenol and Organophosphorous Nitroaromatic Insecticides on the Respiratory Activity of Free and Immobilized Cells of Strains C-11 and BA-11 of Pseudomonas putida

The possibility of using the respiratory activity (RA) of microbial cells (of strains C-11 and BA-11 of Pseudomonas putida) as an instrument for quantitative determination of organophosphorous nitroaromatic insecticides, metaphos and Sumithion, and their hydrolysis product, p-nitrophenol (PNP), has been explored. The dependences of RA on the concentrations of the three compounds were linear within the range 0.5–2.5 mM. The cells of the strain BA-11 exhibited maximum selectivity in the determination of the compounds. The RAs of microbial cells differing in the modes of immobilization (adsorption to carrier surfaces vs. incorporation into gels) have been compared. Prospects of development of the microbial cell-based sensor system for determining metaphos, Sumithion, and PNP in aqueous media are discussed.