Yoshiki Nishikawa

Expression of human thromboxane synthase using a baculovirus system

Human thromboxane (TX) synthase (EC 5.3.99.5) was produced by the baculovirus expression system using cDNA encoding human TX synthase [(1991) Biochem. Biophys. Res. Commun. 78, 1479‐1484]. A recombinant baculovirus TXS7 was expressed in Spodoptera frugiperda Sf9 insect cells. The expressed protein was recognized by monoclonal antibody, Kon 7 raised against human TX synthase [(1990) Blood 76, 80‐85]. The recombinant TX synthase catalyzed the conversion of prostaglandin (PG) H2 to TXA2 and 12‐hydroxy‐heptadecatrienoic acid (HHT). Both conversions of PGH2 to TXA2 and HHT by the expressed TX synthase were completely inhibited by a specific TX synthase inhibitor, OKY‐046 (5 μM).

Stereochemistry of the peptide α-amidation reaction involving two enzymes, peptidylglycine α-hydroxylating monooxygenase (PHM) and peptidylhydroxyglycine N–C lyase (PHL)

Peptidylglycine α-hydroxylating monooxygenase (PHM), the first enzyme involved in the peptide α-amidation, has been shown to convert N-benzoylglycine, a model substrate, stereoselectively to S-N-benzoyl-α-hydroxyglycine, whereas peptidylhydroxyglycine N–C lyase (PHL), the second enzyme, has been found to react exclusively with S-form of the intermediate.