Quantitation of Hydroxyl Radicals Produced by Radiation and Copper-Linked Oxidation of Ascorbate by 2-Deoxy-d-Ribose Method

We have established controlled conditions for studying the reaction of chemically and radiolytically produced hydroxyl radical (OH) with 2-deoxy-D-ribose (2-DR). Ascorbate (ASC) or dithiothreitol (DTT) and cuprous or cupric ions were used to generate the OH-radical. The OH-radical was detected using the classical method of measuring the amount of thiobarbituric acid reactive products (TBARP) formed by OH-mediated 2-DR degradation, but using sensitive fluorescent detection of the TBARP production to quantify the OH-radical. All experiments were performed with adequate O₂ concentrations. The copper reaction with ASC consumes O₂ in a manner that is strongly dependent on copper concentration, and less dependent on ascorbate concentration. For an independent check of the Cu²⁺ catalyzed ASC oxidation kinetics, the decay of ASC absorbency at 265 nm, as well as the increase of H₂O₂ absorbency at 240 nm, were also monitored. These spectral changes agree well with the O₂ consumption data. TBARP production from 2-DR incubated with a Cu²⁺–ASC mixture or γ-irradiated were also compared. γ-Irradiation of 2-DR solutions shows a dose and 2-DR concentration dependent increase of TBARP generation. Other electron donors, such as DTT, are more complicated in their mechanism of OH-radical production. Incubation of 2-DR with Cu²⁺-DTT mixtures shows a delay (50 min) before OH-radical generation is detected. Our results suggest that the Cu²⁺-ASC reaction can be used to mimic the effects of ionizing radiation with respect to OH-radical generation. The good reproducibility and relative simplicity of the 2-DR method with fluorescence detection indicates its usefulness for the quantitation of the OH-radical generated radiolytically or chemically in carefully controlled model systems. © 1997 Elsevier Science Inc.     

Screening,partial purification and characterization of the hyper-thermophilic lipase produced by a new isolate of Bacillus subtilis LP2

Abstract

Lipases are one of the most important catalysts for several industries such as detergent, dairy, and textile industry due to their bio-catalytic ability in aqueous and non-aqueous media. Stability to extreme conditions is an important property since it makes enzymes suitable to several industrial processes. In this study, lipase producing soil bacteria were screened and identified with 16S rDNA sequencing. A new hyper-thermophilic lipase named as Bacillus subtilis LP2 isolate was partially purified by ammonium sulphate precipitation with 17.8-fold purification and 583?U/mg specific activity. Maximum activity was exhibited at pH 7 and 80?°C with the substrate tween 80?K_M and V_max values were calculated as 18.3?mM and 680?U/mg with a catalytic efficiency (k_cat/K_M) of 307?s^?1M^?1. These results indicate that lipase from Bacillus subtilis LP2 can be a valuable candidate for industrial applications such as organic synthesis and fats and oils industry due to their efficient catalysis in higher temperatures.     

PCI proteins eIF3e and eIF3m define distinct translation initiation factor 3 complexes

Background  

PCI/MPN domain protein complexes comprise the 19S proteasome lid, the COP9 signalosome (CSN), and eukaryotic translation initiation factor 3 (eIF3). The eIF3 complex is thought to be composed of essential core subunits required for global protein synthesis and non-essential subunits that may modulate mRNA specificity. Interactions of unclear significance were reported between eIF3 subunits and PCI proteins contained in the CSN.     

Synthesis of biologically active copper oxide nanoparticles as promising novel antibacterial-antibiofilm agents

Abstract

In this study, we aimed to synthesize copper oxide nanoparticles (CuONPs) mediated by plant extract in an environmentally friendly way and to reveal their potential biological activities. Here we synthesized CuONPs by using different concentrations of aqueous leaf extract of Thymbra spicata at 80?°C to obtain Ts1CuONPs and Ts2CuONPs. Biosynthesized nanoparticles were characterized by using UV-Vis, AFM, FTIR, SEM-EDS, TEM, DLS and zeta potential analysis. The antibacterial activity of the nanoparticles was determined by calculation of the inhibition zone and minimum inhibitory concentration against selected bacterial strains. Moreover, the antioxidant activity of the as-synthesized nanoparticles was evaluated based on DPPH radical scavenging activity. The results indicate that the as-synthesized NPs have an average size of 26.8 and 21?nm for Ts1CuONPs and Ts2CuONPs, respectively. The formed CuONPs have more antibacterial action on gram-positive bacteria compared to gram-negative bacteria. In addition, CuONPs demonstrated good inhibition activity against biofilm formation of Staphylococcus aureus (S. aureus). Furthermore, the results showed that the smaller size of the CuONPs caused the higher cytotoxicity on L929 mouse fibroblast cells. The as-synthesized CuONPs exhibit antibacterial and antibiofilm potential against S. aureus, indicating that they may be attractive candidates to use in future therapeutic applications.