Reactivity of nitroxyl-derived sulfinamides

Sulfinamide [RS(O)NH(2)] formation is known to occur upon exposure of cysteine residues to nitroxyl (HNO), which has received recent attention as a potential heart failure therapeutic. Because this modification can alter protein structure and function, we have examined the reactivity of sulfinamides in several systems, including a small organic molecule, peptides, and a protein. Although it has generally been assumed that this thiol to sulfinamide modification is irreversible, we show that sulfinamides can be reduced back to the free thiol in the presence of excess thiol at physiological pH and temperature. We have examined this sulfinamide reduction both in peptides, where a cyclic intermediate analogous to that proposed for asparagine deamidation reactions potentially can contribute, and in a small organic molecule, where the mechanism is restricted to a direct thiolysis. These studies suggest that the contribution from the cyclic intermediate becomes more important in environments with lower dielectric constants. In addition, although sulfinic acid [RS(O)OH] formation is observed upon prolonged incubations in water, reduction of sulfinamides is found to dominate in the presence of thiols. Finally, studies with the cysteine protease, papain, suggest that the reduction of sulfinamide to the free thiol is viable in a protein environment.     

Biochar as a Biocompatible Mild Anti-Inflammatory Supplement for Animal Feed and Agricultural Fields

Biochar is an organic material and high in carbon content, besides its use for energy purposes, it is also a material that serves the purpose of improving soil fertility, organic matter content of soils and removing heavy metals from water and soil. This study aims to investigate the antimicrobial effects of biochar whose beneficial effects on agricultural productivity has been proven by different studies. Scientific literature concerning the antibacterial, antifungal, and antiviral effects of the apricot seed and olive seed biochar is limited. Biochar applications may help to alter the microbial diversity by modifying biological environment either in agriculture or in animal husbandry. Moreover, biochar has been used in animal husbandry to improve animal health especially by regulating the intestinal flora and inflammation in the intestines. Hence, in our study, we investigated the effect of biochar on the growth of Aspergillus niger, Cryphonectria parasitica, Phytophthora cinnamomi, Plenodomus tracheiphilus, Enterococcus casseliflavus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and two different bacteriophage strains. Biochar did not have any direct effect on the growth of either Gram-positive or Gram-negative bacteria, bacteriophages, and fungi. In order to test their direct effects on the immune cells, mammalian macrophages were used and biochar directly reduced the inflammatory cytokine levels produced by the in vitro activated macrophages.     

Vibration parameters affecting vibration-induced reflex muscle activity

Purpose: To determine vibration parameters affecting the amplitude of the reflex activity of soleus muscle during low-amplitude whole-body vibration (WBV).

Materials and methods: This study was conducted on 19 participants. Vibration frequencies of 25, 30, 35, 40, 45, and 50?Hz were used. Surface electromyography, collision force between vibration platform and participant’s heel measured using a force sensor, and acceleration measured using an accelerometer fixed to the vibration platform were simultaneously recorded.

Results: The collision force was the main independent predictor of electromyographic amplitude.

Conclusion: The essential parameter of vibration affecting the amplitude of the reflex muscle activity is the collision force.     

Molybdenum-containing nitrite reductases: Spectroscopic characterization and redox mechanism

Objectives: This review summarizes the spectroscopic results, which will provide useful suggestions for future research. In addition, the fields that urgently need more information are also advised.

Background: Nitrite-NO-cGMP has been considered as an important signaling pathway of NO in human cells. To date, all the four known human molybdenum-containing enzymes, xanthine oxidase, aldehyde oxidase, sulfite oxidase, and mitochondrial amidoxime-reducing component, have been shown to function as nitrite reductases under hypoxia by biochemical, cellular, or animal studies. Various spectroscopic techniques have been applied to investigate the structure and catalytic mechanism of these enzymes for more than 20 years.

Methods: We summarize the published data on the applications of UV-vis and EPR spectroscopies, and X-ray crystallography in studying nitrite reductase activity of the four human molybdenum-containing enzymes.

Results: UV-vis has provided useful information on the redox active centers of these enzymes. The utilization of EPR spectroscopy has been critical in determining the coordination and redox status of the Mo center during catalysis. Despite the lack of substrate-bound crystal structures of these nitrite reductases, valuable structural information has been obtained by X-ray crystallography.

Conclusions: To fully understand the catalytic mechanisms of these physiologically/pathologically important nitrite reductases, structural studies on substrate-redox center interaction are needed.     

Biologically active compounds from two members of the Asteraceae family: Tragopogon dubius Scop. and Tussilago farfara L.

Tragopogon dubius and Tussilago farfara are consumed as vegetables and used in folk medicine to manage common diseases. Herein, the chemical compositions and biological activities of different leaf extracts (ethyl acetate, methanol, and water) of T. dubius and T. farfara were evaluated. The antibacterial, antifungal, and antioxidant abilities of the extracts were tested using different assays including free radical scavenging, reducing power, phosphomolybdenum, and metal chelating assays. Enzyme inhibitory potentials were evaluated against cholinesterases, tyrosinase, α-amylase and α-glucosidase. Complexes of bioactive compounds (chlorogenic and rosmarinic acid) were docked into the enzymatic cavity of α-glucosidase and subjected to molecular dynamic calculation, enzyme conformational stability, and flexibility analysis. T. dubius and T. farfara extracts showed remarkable antioxidant potentials. Ethyl acetate extracts of T. dubius and T. farfara were the most potent inhibitors of acetylcholinesterase and butyrylcholinesterase. T. dubius ethyl acetate extract and T. farfara methanolic extract showed noteworthy activity against α-glucosidase. High performance liquid chromatography analysis revealed the abundance of some phenolic compounds including chlorogenic and rosmarinic acids. Ethyl acetate extract of T. dubius showed notable antifungal activity against all strains. Docking studies showed best pose for chlorogenic acid was stabilized by a network of hydrogen bonds with residues Asp1157, Asp1279, whereas rosmarinic acid showed several hydrogen bonds with Asp1157, Asp1420, Asp1526, Lys1460 and Trp1369. This study further validates the use of T. dubius and T. farfara in traditional medicine, as well as act as a stimulus for further studies for future biomedicine development.

Communicated by Ramaswamy H. Sarma     

Modified nucleotides at the 5' end of human U2 snRNA are required for spliceosomal E-complex formation

U2 snRNA, a key player in nuclear pre-mRNA splicing, contains a 5'-terminal m3G cap and many internal modifications. The latter were shown in vertebrates to be generally required for U2 function in splicing, but precisely which residues are essential and their role in snRNP and/or spliceosome assembly is presently not clear. Here, we investigated the roles of individual modified nucleotides of HeLa U2 snRNA in pre-mRNA splicing, using a two-step in vitro reconstitution/complementation assay. We show that the three pseudouridines and five 2'O-methyl groups within the first 20 nucleotides of U2 snRNA, but not the m3G cap, are required for efficient pre-mRNA splicing. Individual pseudouridines were not essential, but had cumulative effects on U2 function. In contrast, four of five 2'O-methylations (at positions 1, 2, 12, and 19) were individually required for splicing. The in vitro assembly of 17S U2 snRNPs was not dependent on the presence of modified U2 residues. However, individual internal modifications were required for the formation of the ATP-independent early spliceosomal E complex. Our data strongly suggest that modifications within the first 20 nucleotides of U2 play an important role in facilitating the interaction of U2 with U1 snRNP and/or other factors within the E complex.