Classification of polycyclic aromatic hydrocarbons based on mutagenicity in lung tissue through DNA microarray.

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants produced in the combustion of organic matter. Exposure to PAHs raises the risk of lung cancer and inflammatory and allergic disorders such as asthma. DNA microarray technologies have been applied to research on toxicogenomics in the recent years.

Efficient reduction of Cys110 thiyl radical by glutathione in human myoglobin.

Human myoglobin (hMb) possesses a cysteine (Cys) residue which is rare among mammalian Mbs. To investigate the effects of this unique Cys residue at the amino acid position 110 (Cys110) on hMb reactions, we studied the reactions of wild type (WT) methMb and its alanine mutant at Cys110 (C110A) with H(2)O(2), particularly in the presence of reduced glutathione (GSH) which is well known as a reducing agent. The formation rates of the ferryloxo (Fe(IV)=O) species by H(2)O(2) under air were about the same for WT and C110A methMbs, whereas the protein decomposed more in the case of WT than C110A hMb.

Redox-dependent domain rearrangement of protein disulfide isomerase coupled with exposure of its substrate-binding hydrophobic surface.

Protein disulfide isomerase (PDI) is a major protein in the endoplasmic reticulum, operating as an essential folding catalyst and molecular chaperone for disulfide-containing proteins by catalyzing the formation, rearrangement, and breakage of their disulfide bridges. This enzyme has a modular structure with four thioredoxin-like domains, a, b, b', and a', along with a C-terminal extension. The homologous a and a' domains contain one cysteine pair in their active site directly involved in thiol-disulfide exchange reactions, while the b' domain putatively provides a primary binding site for unstructured regions of the substrate polypeptides.

Renaturation of lysozyme with a protein disulfide isomerase chaperone results in enzyme super activity.

When the oxidative refolding of lysozyme (Lyzm) was carried out in the presence of protein disulfide isomerase (PDI) an increased refolding rate and a recovered activity exceeding 100% were reproducibly observed. The origin of this excess activity was investigated by HPLC, SDS-PAGE, and mass spectrometry and assessed using an assay for Lyzm activity. The refolding of Lyzm was achieved through the formation of PDI-Lyzm intermediates and the excess activity was derived from the nascent lysozyme released from these complexes.

Enhancement of the activity of renatured lysozyme by protein disulfide isomerase.

The coexistence of protein disulfide isomerase (PDI) in the oxidative refolding of a fully reduced hen egg white lysozyme brought about a final recovered activity significantly exceeding 100% in addition to the expected acceleration effect. This increase could not be explained by the simple increase produced by suppressing aggregation. After examination of the starting material and assay system, it was concluded that PDI enhances the activity of renatured lysozyme.

The multi-layered structure of Dps with a novel di-nuclear ferroxidase center.

The crystallization of cellular components represents a unique survival strategy for bacterial cells under stressed conditions. A highly ordered, layered structure is often formed in such a process, which may involve one or more than one type of bio-macromolecules. The main advantage of biocrystallization has been attributed to the fact that it is a physical process and thus is independent of energy consumption.

Thermally stable and hydrogen peroxide tolerant manganese peroxidase (MnP) from Lenzites betulinus.

A thermally stable and hydrogen peroxide tolerant manganese peroxidase (MnP) was purified from the culture medium of Lenzites betulinus by ion exchange chromatography, gel filtration and isoelectric focusing chromatography. The MnP purified from L. betulinus (L-MnP) has a molecular mass of 40 kDa and its isoelectric point was determined to be 6.

Effect of negative air ions on computer operation, anxiety and salivary chromogranin A-like immunoreactivity.

The effects of negative air ions on computer operation were examined using a biochemical index of the activity of the sympathetic/adrenomedullary system (i.e. salivary chromogranin A-like immunoreactivity (CgA-like IR)) and a self-report questionnaire (State-Trait Anxiety Inventory, Anxiety State--STAI-S).

Crystal structure of the liganded anti-gibberellin A(4) antibody 4-B8(8)/E9 Fab fragment.

Gibberellins, a class of plant hormones, consist of more than 120 members. Only a few of them are recognized by a receptor that remains unknown. The haptenic mouse monoclonal antibody, 4-B8(8)/E9, was generated against gibberellin A(4) (GA(4)) to recognize biologically active GA selectivity, and we attempted to confirm the binding properties between the antibody and GA(4).