Indonesian
Albanian
Arabic
Armenian
Azerbaijani
Belarusian
Bengali
Bosnian
Catalan
Czech
Danish
Deutsch
Dutch
English
Estonian
Finnish
Français
Greek
Haitian Creole
Hebrew
Hindi
Hungarian
Icelandic
Indonesian
Irish
Italian
Japanese
Korean
Latvian
Lithuanian
Macedonian
Mongolian
Norwegian
Persian
Polish
Portuguese
Romanian
Russian
Serbian
Slovak
Slovenian
Spanish
Swahili
Swedish
Turkish
Ukrainian
Vietnamese
Български
中文(简体)
中文(繁體)
Journal of Biological Chemistry 2002-Jun

Catalytic properties of rice alpha-oxygenase. A comparison with mammalian prostaglandin H synthases.

Hanya pengguna terdaftar yang dapat menerjemahkan artikel
Masuk daftar
Tautan disimpan ke clipboard
Takao Koeduka
Kenji Matsui
Yoshihiko Akakabe
Tadahiko Kajiwara

Kata kunci

Abstrak

Long-chain fatty acids can be metabolized to C(n)(-1) aldehydes by alpha-oxidation in plants. The reaction mechanism of the enzyme has not been elucidated. In this study, a complete nucleotide sequence of fatty acid alpha-oxygenase gene in rice plants (Oryza sativa) was isolated. The deduced amino acid sequence showed some similarity with those of mammalian prostaglandin H synthases (PGHSs). The gene was expressed in Escherichia coli and purified to apparently homogeneous state. It showed the highest activity with linoleic acid and predominantly formed 2-hydroperoxide of the fatty acid (C(n)), which is then spontaneously decarboxylated to form corresponding C(n)(-1) aldehyde. With linoleic or linoleic acids as a substrate, rice alpha-oxygenase formed no product having a lambda(max) at approximately 234 nm, which indicated that the enzyme could not oxygenize the pentadiene system in the substrate. The spectroscopic feature of the purified enzyme in its ferrous state is similar to that of mammalian PGHS, whereas that of dithionite-reduced state showed significant difference. Site-directed mutagenesis revealed that His-158, Tyr-380, and Ser-558 were essential for the alpha-oxygenase activity. These residues are conserved in PGHS and known as a heme ligand, a source of a radical species to initiate oxygenation reaction and a residue involved in substrate binding, respectively. This finding suggested that the initial step of the oxygenation reaction in alpha-oxygenase has a high similarity with that of PGHS. The rice alpha-oxygenase activity was inhibited by imidazole but hardly inhibited by nonsteroidal anti-inflammatory drugs, such as aspirin, ibuprofen, and flurbiprofen, which are known as typical PGHS inhibitors. In addition, peroxidase activity could not be detected with alpha-oxygenase when palmitic acid 2-hydroperoxide was used as a substrate. From these findings, the catalytic resemblance between alpha-oxygenase and PGHS seems to be evident, although there still are differences in their substrate recognitions and peroxidation activities.

Bergabunglah dengan
halaman facebook kami

Database tanaman obat terlengkap yang didukung oleh sains

  • Bekerja dalam 55 bahasa
  • Pengobatan herbal didukung oleh sains
  • Pengenalan herbal melalui gambar
  • Peta GPS interaktif - beri tag herba di lokasi (segera hadir)
  • Baca publikasi ilmiah yang terkait dengan pencarian Anda
  • Cari tanaman obat berdasarkan efeknya
  • Atur minat Anda dan ikuti perkembangan berita, uji klinis, dan paten

Ketikkan gejala atau penyakit dan baca tentang jamu yang mungkin membantu, ketik jamu dan lihat penyakit dan gejala yang digunakan untuk melawannya.
* Semua informasi didasarkan pada penelitian ilmiah yang dipublikasikan

Google Play badgeApp Store badge