Biosynthesis of rice phytoalexin:: Enzymatic conversion of 3β-hydroxy-9β-pimara-7,15-dien-19,6β-olide to momilactone A

被引：36

作者：

Atawong, A

Hasegawa, M

Kodama, O

机构：

[1] Ibaraki Univ, Coll Agr, Lab Phytochem Ecol, Ami, Ibaraki 3000393, Japan

[2] Tokyo Univ Agr & Technol, United Grad Sch Agr Sci, Fuchu, Tokyo 1838509, Japan

来源：

BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY | 2002年 / 66卷 / 03期

关键词：

momilactone A; dehydrogenase; phytoalexin; diterpene; 3 beta-hydroxy-9 beta-pimara-7,15-dien-19,6 beta-olide;

D O I：

10.1271/bbb.66.566

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

Momilactone A, a major rice diterpene phytoalexin, could be synthesized by dehydrogenation at the 3-position of 3beta-hydroxy-9beta-pimara-7,15-dien-19,6beta-olide in rice leaves. The presence of 3beta-hydroxy-9beta-pimara-7,15-dien-19,6beta-olide in UV-irradiated rice leaves was confirmed by comparing the mass spectra and retention times after a GC/MS analysis of the natural and synthetic compounds. The soluble protein fraction from UV-irradiated rice leaves showed dehydrogenase activity to convert 3beta-hydroxy-9beta-pimara-7,15-dien-19,6betaolide into momilactone A. The enzyme required NAD(+) or NADP(+) as a hydrogen acceptor. The optimum pH for the reaction was 8. The K-m value to 3beta-hydroxy-9beta-pimara-7,15-dien-19,6beta-olide was 36 mum when NAD(+) was supplied as a cofactor at a concentration of 1 mm. 3beta-Hydroxy-9beta-pimara-7,15-dien-19,6beta-olide and its dehydrogenase activity were induced in a time-dependent manner by UV irradiation.

引用

页码：566 / 570

页数：5

共 13 条

[1] Biosynthesis of the monoterpenes limonene and carvone in the fruit of caraway - I. Demonstration of enzyme activities and their changes with development [J].