H, C, and N resonance assignments of the amyloidogenic peptide SEM2(49-107) by NMR spectroscopy.

It has been shown that human seminal fluid is a major factor in enhancing HIV activity. The SEM2(49-107) peptide is a product of cleavage after ejaculation by internal prostheses of the semenogelin 2 protein, expressed in seminal vesicles. It is established that the peptide SEM2(49-107) forms amyloid fibrils, which increase probability of contracting HIV infection.

PAP(248-286) Conformational Changes during the Lag Phase of Amyloid Fibril Formation.

The initial stage of fibril formation of C-terminal region PAP(248-286) of human seminal plasma protein prostatic acid phosphatase was considered. Amyloid fibrils from the peptide PAP(248-286) are termed as a semen-derived enhancer of viral infection (SEVI) found in abundant quantities in semen. The kinetics of the amyloid fibril formation process consists of two characteristic phases (lag phase/nucleation phase and growth phase/elongation phase).

Extent of N-Terminus Folding of Semenogelin 1 Cleavage Product Determines Tendency to Amyloid Formation.

It is known that four peptide fragments of predominant protein in human semen Semenogelin 1 (SEM1) (SEM1(86-107), SEM1(68-107), SEM1(49-107) and SEM1(45-107)) are involved in fertilization and amyloid formation processes. In this work, the structure and dynamic behavior of SEM1(45-107) and SEM1(49-107) peptides and their N-domains were described. According to ThT fluorescence spectroscopy data, it was shown that the amyloid formation of SEM1(45-107) starts immediately after purification, which is not observed for SEM1(49-107).

Conformational ensemble of amyloid-forming semenogelin 1 peptide SEM1(68-107) by NMR spectroscopy and MD simulations.

SEM1(68-107) is a peptide corresponding to the region of semenogelin 1 protein from 68 to 107 amino acid position. SEM1(68-107) is an abundant component of semen, which participates in HIV infection enhanced by amyloid fibrils forming. To understand the causes influencing amyloid fibril formation, it is necessary to determine the spatial structure of SEM1(68-107).

The data of heterologous expression protocol for synthesis of N, C-labeled SEM1(68-107) peptide fragment of homo sapiens semenogelin 1.

The semenogelin 1 protein is secreted in the seminal vesicles. After ejaculation it is split into small peptide fragments using internal proteases. It was shown that the fragments SEM1(45-107), SEM1(49-107), SEM1(68-107) (SEM1(86-107) form amyloid fibrils, which increase the possibility of HIV infection.

Dithiophosphate-Induced Redox Conversions of Reduced and Oxidized Glutathione.

Phosphorus species are potent modulators of physicochemical and bioactive properties of peptide compounds. O,O-diorganyl dithiophoshoric acids (DTP) form bioactive salts with nitrogen-containing biomolecules; however, their potential as a peptide modifier is poorly known. We synthesized amphiphilic ammonium salts of O,O-dimenthyl DTP with glutathione, a vital tripeptide with antioxidant, protective and regulatory functions.

NMR resonance assignment and backbone dynamics of a C-terminal domain homolog of orange carotenoid protein.

Photoprotection in cyanobacteria is mediated by the Orange Carotenoid Protein (OCP), a two-domain photoswitch which has multiple natural homologs of its N- and C-terminal domains. Recently, it was demonstrated that C-terminal domain homologs (CTDHs) of OCP are standalone carotenoproteins participating in multidirectional carotenoid transfer between membranes and proteins. Non-covalent embedment of a ketocarotenoid causes dimerization of the small 16-kDa water-soluble CTDH protein; however, dynamic interactions of CTDH with membranes and other proteins apparently require the monomeric state.

In vitro Reconstitution of the S. aureus 30S Ribosomal Subunit and RbfA Factor Complex for Structural Studies.

Ribosome-binding factor A (RbfA) from Staphylococcus aureus is a cold adaptation protein that is required for the growth of pathogenic cells at low temperatures (10-15°C). RbfA is involved in the processing of 16S rRNA, as well as in the assembly and stabilization of the small 30S ribosomal subunit. Structural studies of the 30S-RbfA complex will help to better understand their interaction, the mechanism of such complexes, and the fundamental process such as 30S subunit assembly that determines and controls the overall level of protein biosynthesis.

Backbone and side chain NMR assignments for the ribosome binding factor A (RbfA) from Staphylococcus aureus.

Ribosome binding factor A (RbfA) is a 14.9 kDa adaptive protein of cold shock, which is important for bacterial growth at low temperatures. RbfA can bind to the free 30S ribosomal subunit and interacts with the 5'-terminal helix (helix I) of 16S rRNA.

Effect of triphenylphosphonium moiety on spatial structure and biointeractions of stereochemical variants of YRFK motif.

Chemical modification of therapeutic peptides is an important approach to improving their physicochemical and pharmacokinetic properties. The triphenylphosphonium (TPP) cation has proved to be a powerful modifier; however, its effects on peptide structure and activity remain uncharacterized. In this study, cytoprotective tetrapeptides based on the YRFK opioid motif with L- or D-Arg residues were linked to (triphenylphosphonio)carboxylic acids with ethylene and pentylene spacers (TPP-3 and TPP-6 groups, respectively).

Mechanistic Basis for the Binding of RGD- and AGDV-Peptides to the Platelet Integrin αIIbβ3.

Binding of soluble fibrinogen to the activated conformation of the integrin αIIbβ3 is required for platelet aggregation and is mediated exclusively by the C-terminal AGDV-containing dodecapeptide (γC-12) sequence of the fibrinogen γ chain. However, peptides containing the Arg-Gly-Asp (RGD) sequences located in two places in the fibrinogen Aα chain inhibit soluble fibrinogen binding to αIIbβ3 and make substantial contributions to αIIbβ3 binding when fibrinogen is immobilized and when it is converted to fibrin. Here, we employed optical trap-based nanomechanical measurements and computational molecular modeling to determine the kinetics, energetics, and structural details of cyclic RGDFK (cRGDFK) and γC-12 binding to αIIbβ3.

The Role of Metals in the Reaction Catalyzed by Metal-Ion-Independent Bacillary RNase.

Extracellular enzymes of intestinal microbiota are the key agents that affect functional activity of the body as they directly interact with epithelial and immune cells. Several species of the genus, like , a common producer of extracellular RNase binase, can populate the intestinal microbiome as a colonizing organism. Without involving metal ions as cofactors, binase depolymerizes RNA by cleaving the 3',5'-phosphodiester bond and generates 2',3'-cyclic guanosine phosphates in the first stage of a catalytic reaction.

Antiproliferative and proapoptotic effects of a pyrrole containing arylthioindole in human Jurkat leukemia cell line and multidrug-resistant Jurkat/A4 cells.

Recently, a series of novel arylthioindole compounds, potent inhibitors of tubulin polymerization and cancer cell growth, were synthesized. In the present study the effects of 2-(1H-pyrrol-3-yl)-3-((3,4,5-trimethoxyphenyl)thio)-1H-indole (ATI5 compound) on cell proliferation, cell cycle progression, and induction of apoptosis in human T-cell acute leukemia Jurkat cells and their multidrug resistant Jurkat/A4 subline were investigated. Treatment of the Jurkat cells with the ATI5 compound for 48 hrs resulted in a strong G2/M cell cycle arrest and p53-independent apoptotic cell death accompanied by the induction of the active form of caspase-3 and poly(ADP-ribose) polymerase-1 (PARP-1) cleavage.

Photodynamic responsiveness of human leukemia Jurkat/A4 cells with multidrug resistant phenotype.

Unlabelled: Photodynamic therapy (PDT) is considered as a possible alternative approach to overcoming multidrug resistance (MDR). Analysis of cross-resistance to PDT in cells with different MDR pathways and resistance levels seems to be advantageous for elucidating the general mechanisms of cancer cell resistance to various treatment modalities.

Aim: The aim of the study was to clarify whether the Jurkat/A4 leukemia cells with MDR phenotype are cross-resistant to PDT.

Synthesis and antiproliferative activity of conformationally restricted 1,2,3-triazole analogues of combretastatins in the sea urchin embryo model and against human cancer cell lines.

A series of 1,5-diaryl- and 4,5-diaryl-1,2,3-triazole derivatives of combretastatin A4 were synthesized and evaluated as antimitotic microtubule destabilizing agents using the sea urchin embryo model. Structure-activity relationship studies identified compounds substituted with 3,4,5-trimethoxyphenyl and 3,4-methylenedioxy-5-methoxyphenyl ring A and 4-methoxyphenyl ring B as potent antiproliferative agents with high cytotoxicity against a panel of human cancer cell lines including multi-drug resistant cells. 4,5-Diaryl-1,2,3-triazoles (C-C geometry) were found to be considerably more active than the respective 1,5-diaryl-1,2,3-triazoles (N-C geometry).

Jurkat/A4 cells with multidrug resistance exhibit reduced sensitivity to quercetin.

Background: While multidrug resistance of cancer cells is a well-known phenomenon, little is known on the cross resistance between cytotoxic chemotherapeutical agents and unrelated substances such as natural flavonoids.

Aim: To compare the effects of cytotoxic drug, vepeside and natural flavonoid, quercetin in Jurkat cells and their multidrug-resistant subline Jurkat/A4, in particular to analyze the effector mechanisms of apoptosis and the profiles of several pro- and antiapoptotic proteins in these cells upon exposure to vepeside or quercetin.

Methods: Apoptosis and poly (ADP-ribose) polymerase cleavage were assessed by flow cytometry.

CD73 participates in cellular multiresistance program and protects against TRAIL-induced apoptosis.

The molecular mechanisms underlying the multiresistant phenotype of leukemic and other cancer cells are incompletely understood. We used expression arrays to reveal differences in the gene expression profiles of an apoptosis-resistant T cell leukemia clone (A4) and normally apoptosis-sensitive parental Jurkat cells. CD73 (ecto-5'-nucleotidase) was the most up-regulated gene in the resistant A4 cell clone.

[Multiple medication resistance of apoptosis-resistant tumoral cells].

A4 clone cells, received by CD95-mediated selection from the parental line of Jurkat T-lymphoblast human leukosis, lost their ability of apoptosis as a result of programmed cell death mechanism breakdown. The complex of their acquired phenotypic properties meets tumor progression criteria: oxidative stress resistance, active immune suppression, and low requirement for growth factors. The loss of A4 cell ability of apoptosis is accompanied by acquisition of the phenotype of multiple medication resistance to a wide spectrum of antineoplastic chemotherapeutic drugs and cytotoxins.

Atemonate and Imuteran: novel Russian monoclonal antibody-based therapeutic agents.

The N. Blokhin National Cancer Research Center is one of the few Russian scientific institutions in which hybridoma technology of monoclonal antibody (mAb) production has been successfully established. Using this technology, several dozens of mAbs to various antigens of human leukocytes have been elaborated.

Muramyl peptides augment cytotoxic effect of tumor necrosis factor-alpha in combination with cytotoxic drugs on tumor cells.

We have demonstrated that biologically active muramyl peptides, in particular, glucosaminylmuramyl dipeptide (GMDP), augmented in vitro cytotoxic activity of tumor necrosis factor-alpha (TNF-alpha) against murine fibrosarcoma L929 cells. The introduction of GMDP resulted in cytotoxic effect characteristic for substantially higher dose of cytokine. Even more potent was the combination of GMDP, TNF-alpha and Actinomycin D (ActD).

[The multidrug tumor cell resistance phenotype caused by the impaired cell death program].

The paper shows the role of tumor cell apoptosis induction in the mechanism of cancer cytoreductive therapy and the significance of the impaired cell death program for the pathogenesis of the phenotype of multidrug and radiation resistance resulted from the use of specific antitumor therapy and from the natural course of tumor progression.

[The role of disulfide bridges of the residual protein in chromosomal DNA organization].

The review of literature data and our investigation on the role of disulfide bridges of residual protein (RP) in structural organization of chromosomal DNA is presented. It was studied the action of several S-S cleaving agents (2-mercaptoethanol, dithiothreitol, NaBH4, glutathione reductase) on native DNA-RP complexes, isolating from the different eukaryotic and prokaryotic cells. It was shown, that the thiols result the fragmentation of DNA-RP complex in double-strand subunits of several size (5 x 10(5), (18-20) x 10(6), 70 x 10(6) Da) on dependence of the incubate condition (concentration of thiols, pH, time).

[Measurement of the number of single-strand breaks in DNA of irradiated leukemia P-388 using alkaline denaturation].

Methods, used for indirect determination of single-thread breaks' quantity in DNA, based on it's denaturation in alkali medium and further determination of double-thread DNA quantity by it's fluorescence has been adapted to the measuring of thread disturbances on leukemia P-388 cells. Influence of cells' and alkali concentrations and the time of denaturation of quantity of double-thread DNA has been investigated.