Mitochondrial ATP Synthase and Mild Uncoupling by Butyl Ester of Rhodamine 19, C4R1.

The homeostasis of the transmembrane potential of hydrogen ions in mitochondria is a prerequisite for the normal mitochondrial functioning. However, in different pathological conditions it is advisable to slightly reduce the membrane potential, while maintaining it at levels sufficient to produce ATP that will ensure the normal functioning of the cell. A number of chemical agents have been found to provide mild uncoupling; however, natural proteins residing in mitochondrial membrane can carry this mission, such as proteins from the UCP family, an adenine nucleotide translocator and a dicarboxylate carrier. In this study, we demonstrated that the butyl ester of rhodamine 19, C4R1, binds to the components of the mitochondrial ATP synthase complex due to electrostatic interaction and has a good uncoupling effect. The more hydrophobic derivative C12R1 binds poorly to mitochondria with less uncoupling activity. Mass spectrometry confirmed that C4R1 binds to the ß-subunit of mitochondrial ATP synthase and based on molecular docking, a C4R1 binding model was constructed suggesting the binding site on the interface between the α- and ß-subunits, close to the anionic amino acid residues of the ß-subunit. The association of the uncoupling effect with binding suggests that the ATP synthase complex can provide induced uncoupling.

Heterogeneous Nuclear Ribonucleoproteins Involved in the Functioning of Telomeres in Malignant Cells.

Heterogeneous nuclear ribonucleoproteins (hnRNPs) are structurally and functionally distinct proteins containing specific domains and motifs that enable the proteins to bind certain nucleotide sequences, particularly those found in human telomeres. In human malignant cells (HMCs), hnRNP-A1-the most studied hnRNP-is an abundant multifunctional protein that interacts with telomeric DNA and affects telomerase function. In addition, it is believed that other hnRNPs in HMCs may also be involved in the maintenance of telomere length. Accordingly, these proteins are considered possible participants in the processes associated with HMC immortalization. In our review, we discuss the results of studies on different hnRNPs that may be crucial to solving molecular oncological problems and relevant to further investigations of these proteins in HMCs.

Study of Splicing Factor, Proline- and Glutamine-rich by Proteomic Techniques in Human Malignant and Nonmalignant Cell Lines.

Splicing factor, proline- and glutamine-rich protein (SFPQ), was identified in eight human cultivated cell lines by proteomic approaches. The cell proteins have been separated by means of two-dimensional gel electrophoresis in two modifications and identified by matrix-assisted laser desorption ionization mass spectrometry with further tandem mass spectrometry. The analysis of proteins from three human sarcomas cell lines (RD, U-2 OS and SK-UT-1B), three human renal adenocarcinomas cell lines (A-498, 769-P and OKP-GS), and two prostate adenocarcinomas cell lines (DU-145 and PC-3) revealed several electrophoretic isoforms of SFPQ protein. Differences between theoretical and experimental molecular masses and isoelectric points of SFPQ protein have been observed. Detailed investigation of SFPQ peptides by tandem mass spectrometry has detected new phosphorylation state of threonine residue in 168 position of SFPQ isoform in rhabdomyosarcoma cell line. Furthermore, SFPQ has not been identified during proteomic study of several nonmalignant cell lines, including cultured human mesenchymal stromal cells and myoblasts. However, SFPQ has been found in all malignant cell lines in high quantity. In particular, its fractions are abundant in sarcomas cell lines as opposed to nonmalignant mesenchymal cells. It is assumed that high quantity of SFPQ in sarcomas cell lines may affect tumorigenesis.

Enzyme immunoassay and proteomic characterization of troponin I as a marker of mammalian muscle compounds in raw meat and some meat products.

The skeletal muscle protein troponin I (TnI) has been characterized as a potential thermally stable and species-specific biomarker of mammalian muscle tissues in raw meat and meat products. This study proposed a technique for the quantification of TnI comprising protein extraction and sandwich enzyme-linked immunosorbent assay (ELISA). The technique is characterized by a TnI detection limit of 4.8 ng/ml with quantifiable concentrations ranging from 8.7 to 52 ng/ml. The method was shown to be suitable for detection of TnI in mammalian (beef, pork, lamb, and horse) meat but not in poultry (chicken, turkey, and duck) meat. In particular, the TnI content in beef was 0.40 3 ± 0.058 mg/g of wet tissue. The TnI estimations obtained for the pork and beef samples using ELISA were comparable to the proteomic analysis results. Thus, the quantitative study of TnI can be a convenient way to assess the mammalian muscle tissue content of various meat products.