The effect of confinement on the solid-liquid phase transitions of water was studied by using DSC and FT-IR measurements. Enthalpy changes upon melting of frozen water in MCM-41 and SBA-15 were determined as a function of pore size and found to decrease with decreasing pore size. The melting point also decreased almost monotonically with a decrease in pore size. Analysis of the Gibbs-Thomson relation on the basis of the thermodynamic data showed that there were two stages of interfacial free energy change after the constant region, i.e., below a pore size of 6.0 nm: a gradual decrease down to 3.4 nm and another decrease after a small jump upward. This fact demonstrates that the simple Gibbs-Thomson relation, i.e., a linear relation between the melting point change and the inverse pore size, is limited to the range not far from the melting point of bulk water. FT-IR measurements suggest that the decrease in enthalpy change and interfacial free energy change with decreasing pore size reflect the similarity of the structures of both liquid and solid phases of water in smaller pores at lower temperatures.

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Eighteen key reductases from baker's yeast (Saccharomyces cerevisiae) have been overproduced in Escherichia coli as glutathione S-transferase fusion proteins. A representative set of alpha- and beta-keto esters was tested as substrates (11 total) for each purified fusion protein. The stereoselectivities of beta-keto ester reductions depended both on the identity of the enzyme and the substrate structure, and some reductases yielded both L- and D-alcohols with high stereoselectivities. While alpha-keto esters were generally reduced with lower enantioselectivities, it was possible in all but one case to identify pairs of yeast reductases that delivered both alcohol antipodes in optically pure form. Taken together, the results demonstrate not only that individual yeast reductases can be used to supply important chiral building blocks, but that GST-fusion proteins allow rapid identification of synthetically useful biocatalysts (along with their corresponding genes).

We identified a rapid and novel system to effectively metabolize a large amount of H 2 O 2 in the suspension cells of Scutellaria baicalensis Georgi. In response to an elicitor, the cells immediately initiate the hydrolysis of baicalein 7-O-␤-D-glucuronide by ␤-glucuronidase, and the released baicalein is then quickly oxidized to 6,7-dehydrobaicalein by peroxidases. Hydrogen peroxide is effectively consumed during the peroxidase reaction. The ␤-glucuronidase inhibitor, saccharic acid 1,4-lactone, significantly reduced the H 2 O 2 -metabolizing ability of the Scutellaria cells, indicating that ␤-glucuronidase, which does not catalyze the H 2 O 2 degradation, plays an important role in the H 2 O 2 metabolism. As H 2 O 2 -metabolizing enzymes, we purified two peroxidases using ammonium sulfate precipitation followed by sequential chromatography on CM-cellulose and hydroxylapatite. Both peroxidases show high H 2 O 2 -metabolizing activity using baicalein, whereas other endogenous flavones are not substrates of the peroxidase reaction. Therefore, baicalein predominantly contributed to H 2 O 2 metabolism. Because ␤-glucuronidase, cell wall peroxidases, and baicalein pre-exist in Scutellaria cells, their constitutive presence enables the cells to rapidly induce the H 2 O 2 -metabolizing system.