Akio Ujihara

The Essential Oil of Mentha spicata L. var. crispa Benth. from Nepal

ABSTRACT The essential oil of Mentha spicata var. crispa of Nepalese origin was examined by GC/MS. It was found to be rich in L-carvone. The plant used in this study, which was regenerated from a shoot apex mericlone, was found to have a chromosome number of 2n=48.

Stabilization of Thermolysin Induced by a Decrease in the PH and Dielectric Constant of the Reaction Medium Resulting from a Temperature Increase in Z-Phe-Phe-OMe Synthesis

Thermolysin was stabilized by increasing the reaction temperature from 90°C to 110°C during peptide synthesis of N-(benzyloxycarbonyl)-L-phenylalanyl-L-phenylalanine methyl ester (Z-Phe-Phe-OMe). The stabilization energy was acquired from the drop in both pH and dielectric constant due to the temperature increase. The acquired stabilization energy was as high as ca. 42 kJ/mol (corresponding to 20°C). This acquired stabilization energy did not result from a single event such as a change in electrical charges. It was evaluated as the overall stabilization energy at and around the active site area of the enzyme using an electrostatic potential equation.