The PST-01 protease is secreted by the organic solvent-tolerant microorganism Pseudomonas aeruginosa PST-01 and is stable in the presence of various organic solvents. Therefore, the PST-01 strain and the PST-01 protease are very useful for fermentation and reactions in the presence of organic solvents, respectively. The organic solvent-stable PST-01 protease has two disulfide bonds (between Cys-30 and Cys-58 and between Cys-270 and Cys-297) in its molecule. Mutant PST-01 proteases in which one or both of the disulfide bonds were deleted were constructed by site-directed mutagenesis, and the effect of the disulfide bonds on the activity and the various stabilities was investigated. The disulfide bond between Cys-270 and Cys-297 in the PST-01 protease was found to be essential for its activity. The disulfide bond between Cys-30 and Cys-58 played an important role in the organic solvent stability of the PST-01 protease.

Tellurium (Te) is one of the important metalloids used in industry, and is ubiquitously found in the environment. However, the biological and toxicological effects of Te are still unclear despite its being recognized as a hazardous element. In this study, we attempted to identify urinary Te metabolites (UTMs) in rats by HPLC-ICP-MS and electrospray ionization (ESI)-MS. To unambiguously identify UTMs, two different chromatographic mechanisms, i.e., multi-mode gel filtration and cation exchange columns, were employed. The major UTM detected after ingestion of tellurite was trimethyltelluronium, and no urinary sugar metabolites containing Te were detected despite the fact that the major urinary selenometabolite was a selenosugar (methyl-2acetamido-2-deoxy-1-seleno-b-D-galactopyranoside). Interestingly, the ingestion of tellurite enhanced the excretion of selenometabolites in urine. These results suggest that Te is discretely metabolized from selenium (Se), an essential element belonging to the same group, although it affects the metabolism of Se in rats. Thus, the disturbance of Se metabolism, i.e., the induction of Se deficiency, may be one of the potential toxic effects of Te.

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Variable benzo[b]furan derivatives having (E)- and (Z)-2-alkylcarbamoyl-1-methylvinyl groups at the 2-, 4- and 5-positions and a carboxylpropoxy or (1-phenyl)ethoxy group at the 7-position were prepared to find novel and selective leukotriene B4(LTB4) receptor antagonists. (E)-2-(2-diethylcarbamoyl-1-methylvinyl)-7-(1-phenylethoxy)benzo[b]furan (4v) showed selective inhibition to the human BLT2 receptor (hBLT2). On the other hand, (E)-2-acetyl-4-(2-diethylcarbamoyl-1-methylvinyl)-7-(1-phenylethoxy)benzo[b]furan (7v) inhibited both human BLT(1) receptor (hBLT1) and hBLT2. The (E)-2-(2-diethylcarbamoyl-1-methylvinyl) group lay on approximately the same plane as the benzo[b]furan ring, whereas the (E)-4-(2-diethylcarbamoyl-1-methylvinyl) group had the torsion angle (45.7 degree) from the benzo[b]furan ring plane. However, the (Z)-(2-alkylcarbamoyl-1-methylvinyl)benzo[b]furans were inactive. The inhibitory activity depended on the conformation of the 2-diethylcarbamoyl-1-methylvinyl group.

We investigated the effects of a 1,2-dimyristoyl-sn-glycerol-3-phosphocholine (DMPC) molecular film surrounding microbubbles on their collapse under ultrasound irradiation. We defined the ejection of the internal gas from the microbubble (i.e. “daughter” bubbles) as bubble collapse. In particular, we measured the sound-pressure thresholds for microbubble collapse in water and a DMPC solution. Bubbles with the DMPC film had a smaller resonance size than naked bubbles. The measured contact angles of the bubbles were lower after collapse, implying that DMPC molecules on the bubble surface partially desorbed between the processes of vibration and collapse.