We demonstrate that Co(3)O(4) nanoparticles (NPs) exhibit intrinsic peroxidase-like activity and catalase-like activity. The peroxidase-like activity of the Co(3)O(4) NPs originates from their ability of electron transfer between reducing substrates and H(2)O(2), not from ˙OH radical generated. As peroxidase mimetics, Co(3)O(4) NPs were used for colorimetric determination of H(2)O(2) and glucose.

The white rot fungus Pycnoporus sanguineus produced high amount of laccase in the basal liquid medium without induction. Laccase was purified using ultrafiltration, anion-exchange chromatography, and gel filtration. The molecular weight of the purified laccase was estimated as 61.4 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme oxidized typical substrates of laccases including 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonate), 2,6-dimethoxyphenol, and syringaldazine. The optimum pH and temperature for the purified laccase were 3.0 and 65 degrees C, respectively. The enzyme was stable up to 40 degrees C, and high laccase activity was maintained at pH 2.0-5.0. Sodium azide, L-cysteine, and dithiothreitol strongly inhibited the laccase activity. The purified enzyme efficiently decolorized Remazol Brilliant Blue R in the absence of added redox mediators. The high production of P. sanguineus laccase as well as its decolorization ability demonstrated its potential applications in dye decolorization.

The human p100 protein is a vital transcription regulator that increases gene transcription by forming a physical bridge between promoter-specific activators and the basal transcription machinery. Here we demonstrate that the tudor and SN (TSN) domain of p100 interacts with U small nuclear ribonucleoprotein (snRNP) complexes, suggesting a role for p100 in the processing of precursor messenger RNA. We determined the crystal structure of the p100 TSN domain to delineate the molecular basis of p100's proposed functions. The interdigitated structure resembles a hook, with a hinge controlling the movement and orientation of the hook. Our studies suggest that a conserved aromatic cage hooks methyl groups of snRNPs and anchors p100 to the spliceosome. These structural insights partly explain the distinct roles of p100 in transcription and splicing.

The applications of inorganic nanomaterials as biomimetic catalysts are receiving much attention because of their high stability and low cost. In this work, Co3O4 nanomaterials including nanoplates, nanorods, and nanocubes were synthesized. The morphologies and compositions of the products were characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The catalytic properties of Co3O4 nanomaterials as catalase mimics were studied. The Co3O4 materials with different morphology exhibited different catalytic activities in the order of nanoplates > nanorods > nanocubes. The difference of the catalytic activities originated from their different abilities of electron transfer. Their catalytic activities increased significantly in the presence of calcium ion. On the basis of the stimulation by calcium ion, a biosensor was constructed by Co3O4 nanoplates for the determination of calcium ion. The biosensor had a linear relation to calcium concentrations and good measurement correlation between 0.1 and 1 mM with a detection limit of 4 μM (S/N = 3). It showed high selectivity against other metal ions and good reproducibility. The proposed method was successfully applied for the determination of calcium in a milk sample.